NSLU2-Linux
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HowTo.ForcePowerAlwaysOn History

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March 27, 2011, at 12:02 AM by player61784 -- summarizing with another entry (preview of changes does not work here btw...)
Added lines 328-335:

I made some photos showing the idea of the author above.

http://services.my404.de/share/nslu2/apo-back.jpg

http://services.my404.de/share/nslu2/apo-front.jpg

- player61784

Deleted lines 349-356:

Alternative 9 also working fine on my NSLU2. However I can instantly turn it on again after powering off (don't have to wait 5 seconds to work properly). Also powering off with DO_Shutdown works flawlessly. I used a 100F electrolytic capacitor but mounted it at the front of the PCB using a short wire. Check out pictures of my installation here:

http://services.my404.de/share/nslu2/apo-back.jpg

http://services.my404.de/share/nslu2/apo-front.jpg

- player61784

March 26, 2011, at 11:54 PM by player61784 -- reformatted
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March 26, 2011, at 11:52 PM by player61784 -- new pictures for alternative 9
Added lines 342-346:

Alternative 9 also working fine on my NSLU2. However I can instantly turn it on again after powering off (don't have to wait 5 seconds to work properly). Also powering off with DO_Shutdown works flawlessly. I used a 100F electrolytic capacitor but mounted it at the front of the PCB using a short wire. Check out pictures of my installation here: http://services.my404.de/share/nslu2/apo-back.jpg http://services.my404.de/share/nslu2/apo-front.jpg - player61784

June 17, 2010, at 11:53 AM by DavidM --
Changed lines 424-425 from:
to:
Changed line 433 from:

All of the previous attempts are not recommended for use. If you wish to view them then they are available on the history for this page.

to:

All of the previous attempts are not recommended for use. If you wish to view them then they are available on the history for this page.

June 17, 2010, at 10:49 AM by DavidM -- Added option 14 - R between Q11 & Q10
Added line 16:
Added lines 415-429:

Alternative 14 (One resistor...)

Looking at the Circuit diagram, to turn the slug on you need to turn on Q10, this is normally done from the output of U15 = 1 (NB I think the diagram is wrong as I think this should be driven from the Q output rather than Q-bar). So we need a convenient output that goes to 1 when the power is stable, which is exactly what the output of Q11 does. So just add a resistor (around the same value as R95) between the output of Q11 and the base of Q10 so whenever the output of Q11 is high the slug is on. NB this does mean that even if the slug is powered off by software (which resets Q11) it will come straight back on again - the power and other LEDs? go off and come back on again - this may be a feature or a bug depending on your perspective!

Here is a very bad picture - I managed to trash R91 by trying to solder to it rather than Q11 but it still seems to work!

Attach:Q11-Q10_AutoPowerUP Δ

Having looked at the chip details holding the PR input of U15 active (low) during startup turns the slug on even before Q11 has reset - if both CLR and PR are active then both the outputs of U15 are high and so the slug is on... This may be why some of those solutions sometimes fail to boot, although my slug would intermittently fail to start up even before I started hacking it

--David

December 25, 2009, at 11:32 AM by KB -- caution
Added lines 406-407:

--- I have fried a slug with this method. Use with caution. KB

October 23, 2009, at 10:16 PM by ray -- hub getting hot
Added lines 267-270:

-ray

Hey this method works nice, only the hub and the slug are getting really hot. is this normal?

September 02, 2009, at 02:24 PM by Ken -- add a UPS to \'power on\' solutions
Changed lines 14-15 from:
to:
Added lines 402-407:

Alternative 13 (an Uninterruptable Power Supply -UPS)

If the NSLU is stationary, just plug it into a UPS. No more outage-related power interruptions.

January 29, 2009, at 11:50 AM by Arnaud -- Added 12 alternative
Added line 14:
Added lines 395-400:

Alternative 12 (a USB Y cable)

For those who only use one of the USB port of the NSLU, you can provide power via a normal USB Y-cable on the secnd USB port. I use a standard USB Y-cable which came with my portable external harddisk. One end of the cable (the one with 2 connectors) being plugged in the power source (in my case a PC standing next to the NLSU). The other end of the cable (with one USB connector) in the NLSU.

January 16, 2009, at 02:35 PM by Mike Brady -- Alternative 11 -- minor rewording
Changed lines 378-379 from:

The NSLU2 has a microprocessor power supply supervisor chip, a TS809 (Q11 -- see PowerSwitchingSchematic). This is used to force a latch in a 74HC74 (U15) into the reset or zero state. This keeps power off of the rest of the system, including the processor and the USB ports, whenever the power supply fails to satisfy the TS809's criteria. Once the power supply is good enough, the TS809 releases the reset (U15, pin 1) on the latch, but the latch remains in the zero state -- and the rest of the system remains unpowered -- until the latch is set high (i.e. to 1) by the pressing of the power-on button.

to:

The NSLU2 has a microprocessor power supply supervisor chip, a TS809 (Q11 -- see PowerSwitchingSchematic). Whenever the power supply fails to satisfy the TS809's criteria -- such as when the power is stabilizing after power-up -- the TS809 puts a latch in a 74HC74 (U15) into the reset or zero state (via pin 1 of U15). This in turn keeps power off in the rest of the system and the USB ports. Once the power supply is good enough, the TS809 stops holding the latch in reset, but the latch remains in the zero state -- and the rest of the system remains unpowered -- until the latch is set high (i.e. to 1) by the pressing of the power-on button.

Changed lines 386-389 from:

With this modification, if the TS809 is unhappy with the quality of the power supply, it keeps power off the rest of the system, including the USB ports, just as nature intended. However, if the TS809 is happy, the modification causes it to set the latch, turning on power to the rest of the system, just as if the power-on button had been pressed.

One bonus is this: when you execute the Linux "poweroff" command, the NSLU2 shuts down as normal, and turns off the power for an instant before power is reapplied and the machine restarts. So, you get a short but real power-cycling of the machine, including any bus-powered USB devices.

to:

With this modification, if the TS809 is unhappy with the quality of the power supply, it keeps power off in the rest of the system, including the USB ports, just as nature intended. However, if the TS809 is happy, the modification causes it to set the latch, turning on power to the rest of the system, just as if the power-on button had been pressed.

One bonus is this: when you execute the Linux "poweroff" command, the NSLU2 shuts down as normal, and then turns off the power for an instant before power is reapplied and the machine restarts. So, you get a short but real power-cycling of the machine, including any bus-powered USB devices. I guess that the length of the power-off time is equal to the "Reset Active Timeout Period" of the TS809, nominally 100 mS to 380 mS.

January 16, 2009, at 10:04 AM by Mike Brady -- Alternative 11 -- fix typo
Changed lines 378-379 from:

The NSLU2 has a microprocessor power supply supervisor chip, a TS809 (Q11) -- (see PowerSwitchingSchematic). This is used to force a latch in a 74HC74 (U15) into the reset or zero state. This keeps power off of the rest of the system, including the processor and the USB ports, whenever the power supply fails to satisfy the TS809's criteria. Once the power supply is good enough, the TS809 releases the reset (U15, pin 1) on the latch, but the latch remains in the zero state -- and the rest of the system remains unpowered -- until the latch is set high (i.e. to 1) by the pressing of the power-on button.

to:

The NSLU2 has a microprocessor power supply supervisor chip, a TS809 (Q11 -- see PowerSwitchingSchematic). This is used to force a latch in a 74HC74 (U15) into the reset or zero state. This keeps power off of the rest of the system, including the processor and the USB ports, whenever the power supply fails to satisfy the TS809's criteria. Once the power supply is good enough, the TS809 releases the reset (U15, pin 1) on the latch, but the latch remains in the zero state -- and the rest of the system remains unpowered -- until the latch is set high (i.e. to 1) by the pressing of the power-on button.

January 16, 2009, at 10:03 AM by Mike Brady -- Alternative 11 -- fix references to TS809
Changed lines 378-381 from:

The NSLU2 has a microprocessor power supply supervisor chip, a TS809 (Q11) -- (see PowerSwitchingSchematic). This is used to force a latch in U15 into the reset or zero state. This keeps power off of the rest of the system, including the processor and the USB ports, whenever the power supply fails to satisfy the TS809's criteria. Once the power supply is good enough, the TS809 releases the reset (U15, pin 1) on the latch, but the latch remains in the zero state -- and the rest of the system remains unpowered -- until the latch is set high (i.e. to 1) by the pressing of the power-on button.

However, one can use the inverse of the TS809's output to set the latch high through the latch's preset input (U15, pin 4). To form the inverse, I'm constructing an open-collector inverter from a transistor and resistor as shown below.

to:

The NSLU2 has a microprocessor power supply supervisor chip, a TS809 (Q11) -- (see PowerSwitchingSchematic). This is used to force a latch in a 74HC74 (U15) into the reset or zero state. This keeps power off of the rest of the system, including the processor and the USB ports, whenever the power supply fails to satisfy the TS809's criteria. Once the power supply is good enough, the TS809 releases the reset (U15, pin 1) on the latch, but the latch remains in the zero state -- and the rest of the system remains unpowered -- until the latch is set high (i.e. to 1) by the pressing of the power-on button.

However, one can use the inverse of the TS809's output to set the latch high through the latch's preset input (U15, pin 4). To form the inverse, I'm constructing an open-collector inverter from a transistor and resistor as shown below.

Changed lines 386-387 from:

With this modification, if the TS809 is unhappy with the quality of the power supply, it keeps power off the rest of the system, including the USB ports, just as nature intended. However, if the TS809 is happy, the modification causes it to set the latch, turning on power to the rest of the system, just as if the power-on button had been pressed.

to:

With this modification, if the TS809 is unhappy with the quality of the power supply, it keeps power off the rest of the system, including the USB ports, just as nature intended. However, if the TS809 is happy, the modification causes it to set the latch, turning on power to the rest of the system, just as if the power-on button had been pressed.

January 16, 2009, at 10:00 AM by Mike Brady -- Alternative 11 -- add reference to power supply schematic
Changed lines 378-379 from:

The NSLU2 has a microprocessor power supply supervisor chip, a TS809 (Q11). This is used to force a latch in U15 into the reset or zero state. This keeps power off of the rest of the system, including the processor and the USB ports, whenever the power supply fails to satisfy the TS809's criteria. Once the power supply is good enough, the TS809 releases the reset (U15, pin 1) on the latch, but the latch remains in the zero state -- and the rest of the system remains unpowered -- until the latch is set high (i.e. to 1) by the pressing of the power-on button.

to:

The NSLU2 has a microprocessor power supply supervisor chip, a TS809 (Q11) -- (see PowerSwitchingSchematic). This is used to force a latch in U15 into the reset or zero state. This keeps power off of the rest of the system, including the processor and the USB ports, whenever the power supply fails to satisfy the TS809's criteria. Once the power supply is good enough, the TS809 releases the reset (U15, pin 1) on the latch, but the latch remains in the zero state -- and the rest of the system remains unpowered -- until the latch is set high (i.e. to 1) by the pressing of the power-on button.

January 16, 2009, at 09:55 AM by Mike Brady -- Correct a typo in Alternative 11
Changed lines 378-381 from:

The NSLU2 has a microprocessor power supply supervisor chip, a TS809 (Q11). This is used to force a latch in U16 into the reset or zero state. This keeps power off of the rest of the system, including the processor and the USB ports, whenever the power supply fails to satisfy the TS809's criteria. Once the power supply is good enough, the TS809 releases the reset (U16, pin 1) on the latch, but the latch remains in the zero state -- and the rest of the system remains unpowered -- until the latch is set high (i.e. to 1) by the pressing of the power-on button.

However, one can use the inverse of the TS809's output to set the latch high through the latch's preset input (U16, pin 4). To form the inverse, I'm constructing an open-collector inverter from a transistor and resistor as shown below.

to:

The NSLU2 has a microprocessor power supply supervisor chip, a TS809 (Q11). This is used to force a latch in U15 into the reset or zero state. This keeps power off of the rest of the system, including the processor and the USB ports, whenever the power supply fails to satisfy the TS809's criteria. Once the power supply is good enough, the TS809 releases the reset (U15, pin 1) on the latch, but the latch remains in the zero state -- and the rest of the system remains unpowered -- until the latch is set high (i.e. to 1) by the pressing of the power-on button.

However, one can use the inverse of the TS809's output to set the latch high through the latch's preset input (U15, pin 4). To form the inverse, I'm constructing an open-collector inverter from a transistor and resistor as shown below.

January 16, 2009, at 09:48 AM by Mike Brady -- Update Alternative 11 with pic and minor rewording.
Changed lines 376-385 from:

The problem is related to the fact that the power supply is connected directly to the USB devices. Imagine what might happen after a power failure, when the mains power comes back in an electrically "dirty" way, with missing half-cycles of mains, brownouts and so on. Since the NSLU's power supply is now connected directly to the USB devices, the power coming to them might not be quite right -- it might be a bit low for a while at the start, or it might be a bit slow rising to its nominal voltage. These imperfections could cause the NSLU itself or the USB peripherals to power up incorrectly. On the other hand, if the NSLU's power supply system was working normally, power is applied to the system and to the USB ports only after it is good enough to satisfy the NSLU's power-up supervision circuitry.

The NSLU2 has a microprocessor power supply supervisor chip, a TS809 (Q11). This is used to force a latch in U16 into the reset state whenever the power supply fails to satisfy the TS809's criteria. Once the power supply is good enough, the TS809 releases the reset (U16, pin 1) on the latch, but the latch remains in the zero state -- and the rest of the NSLU2 remains unpowered -- until the latch is brought high by the pressing of the power-on button.

However, one can use the inverse of the TS809's output to set the latch high through the latch's preset input (U16, pin 4). You could use, say, a 74HC04 inverter (or an '05, I guess, open-collector), but you can also use a transistor and resistor in this undemanding situation. <I will attach a PNG of my circuit.> I picked a generally-available NPN bipolar transistor and, out of the air, a 10k resistor. Maybe this could be considerably more -- who knows?

So basically, if the TS809 is unhappy with the quality of the power supply, it keeps power off the rest of the system, including the USB ports, just as nature intended. However, if the TS809 is happy, this modification causes it to set the latch, causing the NSLU's power supply supervisor circuitry to turn on power to the rest of the system, just as if the power-on button had been pressed.

One bonus that I can't really explain is this: when you execute the Linux "poweroff" command, the NSLU2 shuts down as normal, and turns off the power for an instant before power is reapplied and the machine restarts. So, you get a short but real power-cycling of the machine, including any bus-powered USB devices.

to:

The problem is that, by connecting the power supply to the system through the USB ports, the NSLU2's power supervision circuitry is bypassed or sidelined. Imagine what might happen after a mains power failure, when, as often happens, power comes back in an electrically "dirty" way, with missing half-cycles, brownouts and so on. Since the NSLU2's power supply is now connected directly to the system and the USB ports, the power they receive may not be quite right -- it might be a bit low for a while at the start, or it might be a bit slow rising to its nominal voltage. These imperfections could cause the NSLU2 itself or USB peripherals to power up incorrectly. If the NSLU2's power supervision circuitry had not been bypassed, power would only be applied to the system and to the USB ports after it was good enough to satisfy the NSLU's power supervision circuitry.

The NSLU2 has a microprocessor power supply supervisor chip, a TS809 (Q11). This is used to force a latch in U16 into the reset or zero state. This keeps power off of the rest of the system, including the processor and the USB ports, whenever the power supply fails to satisfy the TS809's criteria. Once the power supply is good enough, the TS809 releases the reset (U16, pin 1) on the latch, but the latch remains in the zero state -- and the rest of the system remains unpowered -- until the latch is set high (i.e. to 1) by the pressing of the power-on button.

However, one can use the inverse of the TS809's output to set the latch high through the latch's preset input (U16, pin 4). To form the inverse, I'm constructing an open-collector inverter from a transistor and resistor as shown below.

I picked a generally-available NPN bipolar transistor and a 10k resistor.

With this modification, if the TS809 is unhappy with the quality of the power supply, it keeps power off the rest of the system, including the USB ports, just as nature intended. However, if the TS809 is happy, the modification causes it to set the latch, turning on power to the rest of the system, just as if the power-on button had been pressed.

One bonus is this: when you execute the Linux "poweroff" command, the NSLU2 shuts down as normal, and turns off the power for an instant before power is reapplied and the machine restarts. So, you get a short but real power-cycling of the machine, including any bus-powered USB devices.

January 15, 2009, at 11:09 PM by Mike Brady --
Changed lines 374-375 from:

I've used some of the USB power suggestions on this page to force a remote controller to power up after power outages etc. They're easy to do, but suffer from a problem that might be significant for some applications.

to:

I've used some of the USB power suggestions on this page to force a remote controller based on the NSLU2 to power up after power outages etc. The suggestions are easy to implement, but they suffer from a problem that might be significant for some applications.

Changed lines 386-387 from:

So far, the modification has worked flawlessly. As ever, test and use at your own risk.

to:

So far, the modification has worked flawlessly. As ever, test and use at your own risk.

- Mike Brady, 2009-01-15

January 15, 2009, at 11:00 PM by Mike Brady --
Changed lines 374-375 from:
 I've used some of the USB power suggestions on this page to force a remote controller to power up after power outages etc. They're easy to do, but suffer from a problem that might be significant for some applications.
to:

I've used some of the USB power suggestions on this page to force a remote controller to power up after power outages etc. They're easy to do, but suffer from a problem that might be significant for some applications.

January 15, 2009, at 10:58 PM by Mike Brady --
Added line 369:

Added lines 374-387:
 I've used some of the USB power suggestions on this page to force a remote controller to power up after power outages etc. They're easy to do, but suffer from a problem that might be significant for some applications.

The problem is related to the fact that the power supply is connected directly to the USB devices. Imagine what might happen after a power failure, when the mains power comes back in an electrically "dirty" way, with missing half-cycles of mains, brownouts and so on. Since the NSLU's power supply is now connected directly to the USB devices, the power coming to them might not be quite right -- it might be a bit low for a while at the start, or it might be a bit slow rising to its nominal voltage. These imperfections could cause the NSLU itself or the USB peripherals to power up incorrectly. On the other hand, if the NSLU's power supply system was working normally, power is applied to the system and to the USB ports only after it is good enough to satisfy the NSLU's power-up supervision circuitry.

The NSLU2 has a microprocessor power supply supervisor chip, a TS809 (Q11). This is used to force a latch in U16 into the reset state whenever the power supply fails to satisfy the TS809's criteria. Once the power supply is good enough, the TS809 releases the reset (U16, pin 1) on the latch, but the latch remains in the zero state -- and the rest of the NSLU2 remains unpowered -- until the latch is brought high by the pressing of the power-on button.

However, one can use the inverse of the TS809's output to set the latch high through the latch's preset input (U16, pin 4). You could use, say, a 74HC04 inverter (or an '05, I guess, open-collector), but you can also use a transistor and resistor in this undemanding situation. <I will attach a PNG of my circuit.> I picked a generally-available NPN bipolar transistor and, out of the air, a 10k resistor. Maybe this could be considerably more -- who knows?

So basically, if the TS809 is unhappy with the quality of the power supply, it keeps power off the rest of the system, including the USB ports, just as nature intended. However, if the TS809 is happy, this modification causes it to set the latch, causing the NSLU's power supply supervisor circuitry to turn on power to the rest of the system, just as if the power-on button had been pressed.

One bonus that I can't really explain is this: when you execute the Linux "poweroff" command, the NSLU2 shuts down as normal, and turns off the power for an instant before power is reapplied and the machine restarts. So, you get a short but real power-cycling of the machine, including any bus-powered USB devices.

So far, the modification has worked flawlessly. As ever, test and use at your own risk.

January 15, 2009, at 10:55 PM by Mike Brady -- Another way to force power always on
Added line 13:
Changed lines 369-372 from:
to:

Alternative 11 (a transistor and resistor)

January 15, 2009, at 09:17 AM by Mike Brady --
Deleted line 12:
Changed lines 368-389 from:

ALternative? 11 (a general-purpose NPN Transistor and a Resistor)

I've used one of earlier USB power suggestions to force a remote controller to power up after power outages etc. It's easy to do, but suffers from a problem that might be significant for some applications.

The problem is related to the fact that the power supply is connected directly to the USB devices. Imagine what might happen after a power failure, when the mains power comes back in an electrically "dirty" way, with missing half-cycles of mains, brownouts and so on. Since the NSLU's power supply is now connected directly to the USB devices, the power coming to them might not be quite right -- it might be a bit low for a while at the start, or it might be a bit slow rising to its nominal voltage. These imperfections could cause the NSLU itself or the USB peripherals to power up incorrectly. On the other hand, if the NSLU's power supply system was working normally, power is applied to the system and to the USB ports only after it is good enough to satisfy the NSLU's power-up supervision circuitry.

The NSLU2 has a microprocessor power supply supervisor chip, a TS809 (Q11). This is used to force a latch in U16 into the reset state whenever the power supply fails to satisfy the TS809's criteria. Once the power supply is good enough, the TS809 releases the reset (U16, pin 1) on the latch, but the latch remains in the zero state -- and the rest of the NSLU2 remains unpowered -- until the latch is brought high by the pressing of the power-on button.

However, one can use the inverse of the TS809's output to set the latch high through the latch's preset input (U16, pin 4). You could use, say, a 74HC04 inverter (or an '05, I guess, open-collector), but you can also use a transistor and resistor in this undemanding situation.

Circuit Diagram of the Modification

 I picked a generally-available NPN bipolar transistor and, out of the air, a 10k resistor. Maybe this could be considerably more -- who knows?

So basically, if the TS809 is unhappy with the quality of the power supply, it keeps power off the rest of the system, including the USB ports, just as nature intended. However, if the TS809 is happy, this modification causes it to set the latch, causing the NSLU's power supply supervisor circuitry to turn on power to the rest of the system, just as if the power-on button had been pressed.

One bonus that I can't really explain is this: when you execute the Linux "poweroff" command, the NSLU2 shuts down as normal, and powers down for an instant before power is reapplied and the machine restarts. So, you get a short but real power-cycling of the machine, including any bus-powered USB devices. This looks like a benefit for remote machines.

So far, the modification has worked flawlessly. As ever, test and use at your own risk. Mike Brady

to:
January 15, 2009, at 09:13 AM by Mike Brady -- New Alternative -- allows power cycling
Added line 13:
Changed lines 369-390 from:
to:

ALternative? 11 (a general-purpose NPN Transistor and a Resistor)

I've used one of earlier USB power suggestions to force a remote controller to power up after power outages etc. It's easy to do, but suffers from a problem that might be significant for some applications.

The problem is related to the fact that the power supply is connected directly to the USB devices. Imagine what might happen after a power failure, when the mains power comes back in an electrically "dirty" way, with missing half-cycles of mains, brownouts and so on. Since the NSLU's power supply is now connected directly to the USB devices, the power coming to them might not be quite right -- it might be a bit low for a while at the start, or it might be a bit slow rising to its nominal voltage. These imperfections could cause the NSLU itself or the USB peripherals to power up incorrectly. On the other hand, if the NSLU's power supply system was working normally, power is applied to the system and to the USB ports only after it is good enough to satisfy the NSLU's power-up supervision circuitry.

The NSLU2 has a microprocessor power supply supervisor chip, a TS809 (Q11). This is used to force a latch in U16 into the reset state whenever the power supply fails to satisfy the TS809's criteria. Once the power supply is good enough, the TS809 releases the reset (U16, pin 1) on the latch, but the latch remains in the zero state -- and the rest of the NSLU2 remains unpowered -- until the latch is brought high by the pressing of the power-on button.

However, one can use the inverse of the TS809's output to set the latch high through the latch's preset input (U16, pin 4). You could use, say, a 74HC04 inverter (or an '05, I guess, open-collector), but you can also use a transistor and resistor in this undemanding situation.

Circuit Diagram of the Modification

 I picked a generally-available NPN bipolar transistor and, out of the air, a 10k resistor. Maybe this could be considerably more -- who knows?

So basically, if the TS809 is unhappy with the quality of the power supply, it keeps power off the rest of the system, including the USB ports, just as nature intended. However, if the TS809 is happy, this modification causes it to set the latch, causing the NSLU's power supply supervisor circuitry to turn on power to the rest of the system, just as if the power-on button had been pressed.

One bonus that I can't really explain is this: when you execute the Linux "poweroff" command, the NSLU2 shuts down as normal, and powers down for an instant before power is reapplied and the machine restarts. So, you get a short but real power-cycling of the machine, including any bus-powered USB devices. This looks like a benefit for remote machines.

So far, the modification has worked flawlessly. As ever, test and use at your own risk. Mike Brady

December 10, 2008, at 11:35 PM by gdelama --
December 10, 2008, at 11:34 PM by gdelama -- New method of ForcePowerAlwaysOn
Added line 12:
Added lines 334-368:

Alternative 10 (a simple capacitor + diode)

This method is an enhancement of method 9. It keeps the power switch fully functional and eliminates the small drawback of the method 9 (that the power needs to be down for 5-10 seconds to turn the slug on). Now the NSLU2 always restarts.

I've added a diode in parallel of R94. When power fails the 100uF capacitor discharge itself immediatly trought the diode.

Now an "ascii art" electrical scheme, in the future I'll upload some images.


+---+-----
    |   | 
    |   |
   ---  |diode 1N4001 or equiv.
   |R| ===
   |9| / \    +-------- 
   |4| ---    |
   ---  |     | 
    |   |    4|  U15
    +---+-----+ 
    |         | 74HC74
   +|         |
   ===        |________

   === 100uF   
    |
    |

+-------

I've tested it successfully on my slug.

- 10-12-2008 gdelama

November 22, 2008, at 01:59 PM by mwester -- restore
November 11, 2008, at 11:04 PM by garpinc --
Changed lines 27-28 from:
  • Solution 6 appears to be most non-intrusive solution. I have confirmed with cable in port 1: http://www.amazon.com/USB-Power-Adapter-Y-Cable/dp/B000JIOHDE/ref=pd_bbs_sr_1?ie=UTF8&s=electronics&qid=1226444397&sr=8-1
to:
  • Solution 5 appears to be most non-intrusive solution. I have confirmed with cable in port 1: http://www.amazon.com/USB-Power-Adapter-Y-Cable/dp/B000JIOHDE/ref=pd_bbs_sr_1?ie=UTF8&s=electronics&qid=1226444397&sr=8-1
November 11, 2008, at 11:03 PM by garpinc --
Changed lines 27-28 from:
to:
  • Solution 6 appears to be most non-intrusive solution. I have confirmed with cable in port 1: http://www.amazon.com/USB-Power-Adapter-Y-Cable/dp/B000JIOHDE/ref=pd_bbs_sr_1?ie=UTF8&s=electronics&qid=1226444397&sr=8-1
October 18, 2008, at 05:22 PM by Ralph Finch --
Changed lines 318-319 from:

I confirm it did work with the recommended 100uF electrolytic capacitor. I soldered it directly to pins 4(+) and 7(-) of U15. The capacitor was laying flat with it's end almost at the edge of the circuit board (opposite the reset button). Two soldered leads that were protruding through the board had to be cut short so that it could lay flat. The capacitor lying on it's side was still too tall to fit back in the case, so I deformed the case by using heat and a tool to push from the inside. I used a heat gun and the tool was the cylindrical end of an old computer microphone (about as big around as a dime). (p.s. Using a 10uF ceramic capacitor will not work; I tried.)

to:

I confirm it did work with the recommended 100uF electrolytic capacitor. I soldered it directly to pins 4(+) and 7(-) of U15. The capacitor was laying flat with its end almost at the edge of the circuit board (opposite the reset button). Two soldered leads that were protruding through the board had to be cut short so that it could lay flat. The capacitor lying on its side was still too tall to fit back in the case, so I deformed the case by using heat and a tool to push from the inside. I used a heat gun and the tool was the cylindrical end of an old computer microphone (about as big around as a dime). (p.s. Using a 10uF ceramic capacitor will not work; I tried.)

October 11, 2008, at 04:57 PM by syrou --
Changed lines 139-140 from:

Trued nspon suggestion about using a DS1233M-5+ part, and it works perfectly, with the added bouns of the straight forward pinout comparing it to the DS1233-10 one. Thanks nspon!

to:

Tried nspon suggestion about using a DS1233M-5+ part, and it works perfectly, with the added bouns of the straight forward pinout comparing it to the DS1233-10 one. Thanks nspon!

October 11, 2008, at 04:57 PM by syrou --
Added lines 138-143:

Trued nspon suggestion about using a DS1233M-5+ part, and it works perfectly, with the added bouns of the straight forward pinout comparing it to the DS1233-10 one. Thanks nspon!

--- syrou


October 09, 2008, at 03:19 PM by err -- errer
Added lines 324-325:

(2008-10-09: the picture says 1F cap, that would be an error, then)

July 18, 2008, at 06:04 AM by Colin -- Added confirmation and comment for method 9.
Added lines 310-315:

- ?

I confirm it did work with the recommended 100uF electrolytic capacitor. I soldered it directly to pins 4(+) and 7(-) of U15. The capacitor was laying flat with it's end almost at the edge of the circuit board (opposite the reset button). Two soldered leads that were protruding through the board had to be cut short so that it could lay flat. The capacitor lying on it's side was still too tall to fit back in the case, so I deformed the case by using heat and a tool to push from the inside. I used a heat gun and the tool was the cylindrical end of an old computer microphone (about as big around as a dime). (p.s. Using a 10uF ceramic capacitor will not work; I tried.)

- Colin

April 30, 2008, at 09:30 AM by lavileric -- edit my contrib
Changed lines 310-311 from:

Pictures for alternative9

to:

Pictures for alternative 9

April 30, 2008, at 09:29 AM by lavileric -- edit my contrib
Changed lines 310-311 from:
to:

Pictures for alternative9

April 30, 2008, at 09:27 AM by lavileric -- edit my contrib
Changed lines 310-313 from:

# pictures for method9

method9 works also on my slug. I found some pictures on the net explaining how to do the hacking.

to:

#pictures for alternative9

alternative 9 works also on my slug. I found some pictures explaining how to do the hacking.

April 30, 2008, at 09:23 AM by lavileric -- picture for method 9
Added lines 310-317:

# pictures for method9

method9 works also on my slug. I found some pictures on the net explaining how to do the hacking.

http://1wt.eu/articles/nslu2/

- lavileric

March 04, 2008, at 09:42 PM by NSpon -- Recommend DS1223M part
Added lines 132-137:

The trick here is to find a part with an open-drain output whose power-on time is longer than the rather loosely specified 140-500msec provided by the TS809 (see PowerSwitchingSchematic). I would recommend the DS1233M part which runs 300msec - 1 second, its chances of lasting longer than the TS809 are higher.

--- nspon


March 04, 2008, at 07:38 AM by Netamego --
Added lines 128-131:

I used DS1233? also, and works like a charm. Power button functions OK. Auto power on, after supply failure. Thanks to everybody!!


February 10, 2008, at 09:08 PM by Michael K --
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(I do not know how to uplaod....)

to:

(I do not know how to upload....)

February 10, 2008, at 09:08 PM by Michael K -- Added method using a single capacitor
Changed lines 296-297 from:
to:

(I do not know how to uplaod....)

February 10, 2008, at 08:53 PM by Michael --
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Added lines 287-298:

Alternative 9 (a simple capacitor)

This method keeps the power switch fully functional. The only small drawback is that the power needs to be down for 5-10 seconds to turn the slug on.

The only component needed is a 100F electrolytic capacitor that is connected between ground and R94. Connect + connection of the capacitor to the end of R94 that is also connected to U15 - pin 4 (74HC74). The cap can be mounted on top of the hole in the pcb that is next to the power jack.

Attach:NSLU2-Power_up_Cap_top.jpg Δ Attach:NSLU2-Power_up_Cap_bottom.jpg Δ

This works on both of my slugs.

December 22, 2007, at 08:10 PM by Phil Endecott -- Typos, answer question. *Please ask questions on the mailing list, not by editting Wiki pages!*
Changed lines 226-228 from:

Works like: After Power On wait fr two seconds and then send a short impuls to the D-Flipflop (U15/Pin4) on the Slugs Motherboard.

to:

Works like: After Power On wait for two seconds and then send a short impulse to the D-Flipflop (U15/Pin4) on the Slug's motherboard.

Changed lines 263-264 from:

There is a vartiaion of method 6, but needs minor hardware modification. Open the slug, place a wire between the power jack (+5V is the closest to U16) and any +5V of the USB ports, the easiest place is the unfitted F1 fuse. Works fine, the drawbacks are that you can not power it off with the button, but it restarts at least in Debian. Also you can supply up to 2A on the USB port, but this maybe is not a real drawback.

to:

There is a vartiaion of method 6, but needs minor hardware modification. Open the slug, place a wire between the power jack (+5V is the closest to U16) and any +5V of the USB ports, the easiest place is the unfitted F1 fuse (either end). Works fine, the drawbacks are that you can not power it off with the button, but it restarts at least in Debian. Also you can supply up to 2A on the USB port, but this maybe is not a real drawback.

Deleted lines 266-268:

Clarification needed: Which side if the F1 fuse should the wire go to. -Kirk

December 20, 2007, at 12:27 AM by kirk -- asked for clarification of F1 fuse wire
Added lines 267-269:

Clarification needed: Which side if the F1 fuse should the wire go to. -Kirk

November 01, 2007, at 07:26 PM by Darek --
Changed lines 21-31 from:
 The most recent is easy to build, and works for some. 

 The second is a bit harder to build, but has been in service longer.

 (There is insufficient evidence to show if the current two solutions are equally effective.)

 The third solution uses a microcontroller to create solution 2 behavior with a single chip.

 The fourth solution uses discrete electronics and works as alternative 2 or 3 
to:
  • The most recent is easy to build, and works for some.
  • The second is a bit harder to build, but has been in service longer.

(There is insufficient evidence to show if the current two solutions are equally effective.)

  • The third solution uses a microcontroller to create solution 2 behavior with a single chip.
  • The fourth solution uses discrete electronics and works as alternative 2 or 3
October 21, 2007, at 04:57 AM by forrestv -- mod
Added lines 272-275:

This has worked fine for me. Power previously was a problem because of frequent power outages.

- forrestv

October 13, 2007, at 04:09 PM by Tom SW --
Changed lines 283-284 from:

Now just the normal power supply and the USB end of the USB power cord into the slug, and you'll be doing the same as in Method 7.

to:

Now just plug the normal power supply and the USB end of the USB power cord into the slug, and you'll be doing the same as in Method 7.

October 13, 2007, at 04:08 PM by Tom SW --
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to:

Added line 277:
Added line 279:
Added line 282:
October 13, 2007, at 04:07 PM by Tom SW -- Added a variant of method 7 that doesn\'t require opening the case.
Added line 10:
Changed lines 252-253 from:

Unfortunately this method didnt work for me. Only the power button light on the SLUG comes on and the SLUG doesnt start itself up.

to:

Unfortunately this method didn’t work for me. Only the power button light on the SLUG comes on and the SLUG doesn’t start itself up.

Added lines 272-283:

Alternative 8 (a simple USB power cable)

This is method 7, but you don't need to open the case. You need a "USB power cable"; mine came with a 4 port PCMCIA usb adaptor: one end is a USB plug, the other is a simple DC jack, about 2mm diameter, with + on the inside, - on the outside. Cut off a small section of the slug's power lead's insulation on the + wire, which has a grey stripe on it - just enough to expose the bare wire. Unfold a paperclip and wind it round the power lead so that it makes contact with the exposed wire (pliers help here). Use some insulating tape to tidy up and secure everything, so that just one end of the paperclip remains exposed, and use a pair of pliers to make a bit of a kink in it. Now you can slot it inside the USB power cord's jack, and they will hold firm. Now just the normal power supply and the USB end of the USB power cord into the slug, and you'll be doing the same as in Method 7.

- Tom SW

July 18, 2007, at 05:52 PM by Viruseb --
Added lines 216-219:

--- Sb

You can also use a Microchip pic12f200. it's a 6 pins tssop so it's kinda difficult to sodler but it take virtually no space. And it costs nothing thank to Microship sample program

July 02, 2007, at 05:41 PM by fcarolo -- removed false wikilinks
Changed lines 214-215 from:

I've used an ATtiny11?, which is even cheaper than the ATtiny13? (about €0.60). Here's the assembler source code. If you're not interested in source, you can download the hex file, which can be programmed directly using AVRStudio? or avrdude.

to:

I've used an ATtiny11, which is even cheaper than the ATtiny13 (about €0.60). Here's the assembler source code. If you're not interested in source, you can download the hex file, which can be programmed directly using AVRStudio or avrdude.

July 02, 2007, at 05:26 PM by Olivier Guilyardi -- Correct MPC120 to MCP120
Changed lines 126-127 from:

We've also been successful with a Dallas DS1233-10. It was easier to find here in France than the MPC120, from Radiospares who delivered the chips in 1 business day. Please note that the pinout of the DS1233-10 is slightly different from the MPC120.

to:

We've also been successful with a Dallas DS1233-10. It was easier to find here in France than the MCP120, from Radiospares who delivered the chips in 1 business day. Please note that the pinout of the DS1233-10 is slightly different from the MCP120.

July 02, 2007, at 05:25 PM by Olivier Guilyardi -- Add small precision to DS1233-10 paragraph
Changed lines 126-127 from:

We've also been successful with a Dallas DS1233-10. It was easier to find here in France, from Radiospares who delivered the chips in 1 business day. Please note that the pinout of the DS1233-10 is slightly different from the MPC120.

to:

We've also been successful with a Dallas DS1233-10. It was easier to find here in France than the MPC120, from Radiospares who delivered the chips in 1 business day. Please note that the pinout of the DS1233-10 is slightly different from the MPC120.

July 02, 2007, at 05:17 PM by Olivier Guilyardi -- Add note about Dallas DS1233-10 to alternative 1
Added lines 125-130:

We've also been successful with a Dallas DS1233-10. It was easier to find here in France, from Radiospares who delivered the chips in 1 business day. Please note that the pinout of the DS1233-10 is slightly different from the MPC120.

--- olivier


June 07, 2007, at 06:47 PM by mhx -- Fix links for ATtiny11 section
Changed lines 208-209 from:

I've used Δ an ATtiny11?, which is even cheaper than the ATtiny13? (about €0.60). Here's the assembler source code Δ. If you're not interested in source, you can download the hex file Δ, which can be programmed directly using AVRStudio? or avrdude.

to:

I've used an ATtiny11?, which is even cheaper than the ATtiny13? (about €0.60). Here's the assembler source code. If you're not interested in source, you can download the hex file, which can be programmed directly using AVRStudio? or avrdude.

June 07, 2007, at 06:43 PM by mhx -- ATtiny11
Added lines 208-209:

I've used Δ an ATtiny11?, which is even cheaper than the ATtiny13? (about €0.60). Here's the assembler source code Δ. If you're not interested in source, you can download the hex file Δ, which can be programmed directly using AVRStudio? or avrdude.

June 04, 2007, at 04:48 PM by fcarolo -- removed false wikilinks
Changed line 115 from:

I hace successfully used a MCP120?/475HI.

to:

I hace successfully used a MCP120/475HI.

Changed lines 120-121 from:

For what it's worth, I have used a Dallas Semiconductor DS1233?

to:

For what it's worth, I have used a Dallas Semiconductor DS1233

June 04, 2007, at 05:31 AM by robby --
Added lines 120-123:

For what it's worth, I have used a Dallas Semiconductor DS1233?

--- robby

January 26, 2007, at 01:27 AM by lorenz117 -- added comment regarding usb powering and 1-wire networks
Added lines 239-241:

-- lor If you're going to use a 1-wire network (via a 1-wire USB adaptor) with your slug note that any method that provides power directly to the usb port will give you 1-wire network errors. None of your devices will work. Doesn't seem to damage them, as they'll come back to life once the usb power is removed.

November 20, 2006, at 04:16 PM by Phil Endecott -- Homophone
Changed lines 248-249 from:

There is a vartiaion of method 6, but needs minor hardware modification. Open the slug, place a wire between the power jack (+5V is the closest to U16) and any +5V of the USB ports, the easiest place is the unfitted F1 fuse. Works fine, the drawbacks are that you can not power it off with the button, but it restarts at list in Debian. Also you can supply up to 2A on the USB port, but this maybe is not a real drawback.

to:

There is a vartiaion of method 6, but needs minor hardware modification. Open the slug, place a wire between the power jack (+5V is the closest to U16) and any +5V of the USB ports, the easiest place is the unfitted F1 fuse. Works fine, the drawbacks are that you can not power it off with the button, but it restarts at least in Debian. Also you can supply up to 2A on the USB port, but this maybe is not a real drawback.

November 19, 2006, at 01:11 PM by jiauka --
Changed lines 245-246 from:

to:

November 19, 2006, at 01:11 PM by jiauka --
Added line 9:
Changed lines 245-246 from:

There is a variaion on this approach, but needs minor hardware modification. Open the slug, place a wire between the power jack (+5V is the closest to U16) and any +5V of the USB ports, the easiest place is the unfitted F1 fuse. Works fine, the drawbacks are that you can not power it off with the button, but it restarts at list in Debian. Also you can supply up to 2A on the USB port, but this maybe is not a real drawback.

to:

Alternative 7 (a simple wire)

There is a vartiaion of method 6, but needs minor hardware modification. Open the slug, place a wire between the power jack (+5V is the closest to U16) and any +5V of the USB ports, the easiest place is the unfitted F1 fuse. Works fine, the drawbacks are that you can not power it off with the button, but it restarts at list in Debian. Also you can supply up to 2A on the USB port, but this maybe is not a real drawback.

Added line 251:
November 19, 2006, at 01:09 PM by jiauka -- hardware alternative without components
Added lines 244-246:

There is a variaion on this approach, but needs minor hardware modification. Open the slug, place a wire between the power jack (+5V is the closest to U16) and any +5V of the USB ports, the easiest place is the unfitted F1 fuse. Works fine, the drawbacks are that you can not power it off with the button, but it restarts at list in Debian. Also you can supply up to 2A on the USB port, but this maybe is not a real drawback.

-jiauka

August 22, 2006, at 03:01 PM by if -- MCP120/475HI used
Added lines 112-118:

---

I hace successfully used a MCP120?/475HI. works great.

--- if

August 15, 2006, at 05:02 AM by MichaelWei -- added new usb poweron alternative
Added line 8:
Added lines 232-236:

Alternative 6 (without hardware modification)

This method is similar to alternative 5, but involves either constructing your own cable or somehow providing +5V to the USB ports. See more HowTo.AutoPowerSlugViaUSB. Note that it is unknown how this actually works and you could possibly fry your slug and everything connected on it if you manage to supply more than +5v

May 06, 2006, at 04:17 PM by theklone --
Changed lines 222-223 from:

picture

to:

http://img187.imageshack.us/img187/6628/hubpoweredslug6rs.jpg

Added lines 226-229:

Unfortunately this method didnt work for me. Only the power button light on the SLUG comes on and the SLUG doesnt start itself up.

-theklone

April 23, 2006, at 05:11 PM by exe -- Add pic of a hub powerd slug.
Added lines 221-225:

Here is a image of my slug running with the power supply from the hub. This is working great and there is no need of an extra power supply for the slug, which means you can save some energy too. picture

-exe

April 19, 2006, at 05:52 AM by Chas --
Added lines 219-220:

-Chas

April 19, 2006, at 05:52 AM by Chas --
Changed lines 217-218 from:
to:

I find this approach almost too effective. The NSLU2 stays on all the time...there seems to be no way to turn it off!!! The off button doesn't work, so you've got to unplug the USB hub and the NSLU2. But otherwise, I've been using this approach for a few months without a glitch.

April 07, 2006, at 06:21 PM by G de Zwart -- fourth instead of forth, uses instead of used
Changed lines 27-28 from:
 The forth solution used discrete electronics and works as alternative 2 or 3 
to:
 The fourth solution uses discrete electronics and works as alternative 2 or 3 
March 23, 2006, at 03:31 PM by TimSmall --
Added lines 105-110:

---

A brief description of how this works would be useful, I think I know from looking at the datasheet, but confirmation would be good - what would be the effect of changing the 450 (which operates the power button when vdd falls below 4.50v) with other types - e.g. the 475 (which operates at 4.75v) - the 475 is a lot easier for me to get hold of.

--- tsmall

March 22, 2006, at 02:59 AM by jpcalvin -- Update
Added lines 99-104:

---

The MCP120 worked fine in my slug, at least in regard to the power-on. It boots fine every time power is applied but the power button does not work correctly anymore. It still shuts down when the power button is pressed (e.g. the slug is no longer responds to pings and the disk activity ceases), but all the lights remain on. It will not fully power down unless it is unplugged. It doesn't appear to be a big deal, but you might want to be aware of the potential problem.

--- jpcalvin

February 10, 2006, at 08:44 PM by michael --
Changed line 4 from:
to:
February 10, 2006, at 08:42 PM by michael --
Changed line 4 from:
to:
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Alternative 2 (7474 flip-flop)

to:

Alternative 2 (74HC123 monoflop)

February 09, 2006, at 11:36 PM by Patrick Schneider -- Formatting
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What is this page about:

to:
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Four solutions are offered below:

to:

Five solutions are offered below:

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Howto

Alternative 1

to:

Alternative 1 (MCP120-450DI/TO)

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Alternative 2

to:

Alternative 2 (7474 flip-flop)

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Alternative 3

to:

Alternative 3 (Single chip variant of Alternative 2)

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Alternative 4

to:

Alternative 4 (basic components)

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Previous Howtos

to:

Previous Howtos

February 07, 2006, at 01:10 PM by carsten -- Power on without hardware modification
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to:

-- Carsten

February 07, 2006, at 09:19 AM by carsten -- Power on without hardware modification
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Alternative 5 (without hardware change)

to:

Alternative 5 (without hardware modification)

February 07, 2006, at 09:18 AM by carsten -- Power on without hardware change
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Alternative 5 (without hardware change)

February 07, 2006, at 09:17 AM by carsten -- Power always on without hardware change
Added lines 189-193:

I connected a 2.5'' external HDD case to port 1 of the NSLU. To establish a stable power supply to the HDD case (even though not necessary for the used HDD), I used a separate USB-to-DC cable, connecting the power plug of the HDD case with a free USB port of an external USB hub. To my surprise, the NSLU started and booted even though I hadn't pressed its power button. By now, there are no problems or restrictions in functionality of the NSLU or of the HDD. Shutdown of the NSLU works fine, but the box doesn't switch off (the on/off-button stays lit all the time). For me, this seems to be a very simple-to-install and very practical solution, as I want to switch the NSLU by using a remote controlled power supply.


February 05, 2006, at 04:19 PM by eFfeM -- added ref to HowTo/AutoRebootOnPanic
Changed lines 19-20 from:
to:

Note that this only reboots when a power failure occurs. If you also want to reboot on a kernel panic, have a look at AutoRebootOnPanic

February 04, 2006, at 12:10 PM by Michael --
Changed lines 7-8 from:

Four solutions are offered below: The most recent is easy to build, and works for some. The second is a bit harder to build, but has been in service longer. There is insufficient evidence to show if the current two solutions are equally effective. The third solution uses a microcontroller to create solution 2 behavior with a single chip. The forth solution used discrete electronics and works like alternative 2 oder 3 (old school design)

to:

Four solutions are offered below:

 The most recent is easy to build, and works for some. 

 The second is a bit harder to build, but has been in service longer.

 (There is insufficient evidence to show if the current two solutions are equally effective.)

 The third solution uses a microcontroller to create solution 2 behavior with a single chip.

 The forth solution used discrete electronics and works as alternative 2 or 3 
February 04, 2006, at 12:06 PM by Michael --
Changed lines 7-8 from:

Three solutions are offered below: The most recent is easy to build, and works for some. The second is a bit harder to build, but has been in service longer. There is insufficient evidence to show if the current two solutions are equally effective. The third solution uses a microcontroller to create solution 2 behavior with a single chip.

to:

Four solutions are offered below: The most recent is easy to build, and works for some. The second is a bit harder to build, but has been in service longer. There is insufficient evidence to show if the current two solutions are equally effective. The third solution uses a microcontroller to create solution 2 behavior with a single chip. The forth solution used discrete electronics and works like alternative 2 oder 3 (old school design)

February 04, 2006, at 11:52 AM by Michael --
Changed lines 172-174 from:

Works like: After PowerOn? wait fr two seconds and then send a short impuls to the D-Flipflop on the Slugs Motherboard

to:

Works like: After Power On wait fr two seconds and then send a short impuls to the D-Flipflop (U15/Pin4) on the Slugs Motherboard.

February 04, 2006, at 11:50 AM by Michael --
Added lines 162-163:

Changed lines 166-167 from:

Works like circuit no.2 or 3

to:

Works like circuit No.2 or 3, needs:

2 Transistors, 5 Resistors, 2 Capicators, 2 Diodes

Added lines 172-174:

Works like: After PowerOn? wait fr two seconds and then send a short impuls to the D-Flipflop on the Slugs Motherboard

February 03, 2006, at 08:37 PM by Michael --
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http://www.wegzumselbst.de/dat/PowerON-circuit-nslu2.GIF

February 02, 2006, at 12:10 PM by Michael --
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Works like circuit no.2 oder 3

to:

Works like circuit no.2 or 3

February 02, 2006, at 12:09 PM by Michael -- New PowerOn solution
Added lines 162-165:

Alternative 4

Works like circuit no.2 oder 3

December 28, 2005, at 07:22 PM by tio -- brownout voltage of AVR
Added lines 149-161:

Then AVR tiny13 has 3 "brown-out detection level" Fuses:

4.3V, 2.7V and 1.8V

Could it be that the wrong fuse was blown?

--- tio

Would it be possible to post the source code and make (batch) file? The code is not very complecate but for someone with no knowledge abut AVR and Bascom it would give a starting point.

--- tio

December 04, 2005, at 07:24 AM by tman --
Changed lines 13-14 from:

As Edi suggests below, the Microchip MCP120-450DI/TO is a cheap, easy to implement and reliable solution. The part can be bought from Mouser electronics for $0.35 plus shipping or from Digikey for $0.43 plus shipping. For US shipment from Mouser the cheapest option in first class mail which always ends up cheaper than the estimate they give. The Mouser electronics part number is 579-MCP120-450DI/TO and the Digikey part number is MCP120-450DI/TO-ND. You can get sample quantities of the MCP120-450DI/TO from the Microchip sample program. You may request up to 5 part numbers.

to:

As Edi suggests below, the Microchip MCP120-450DI/TO is a cheap, easy to implement and reliable solution. The part can be bought from Mouser electronics for $0.35 plus shipping or from Digikey for $0.43 plus shipping. For US shipment from Mouser the cheapest option is first class mail which always ends up cheaper than the estimate they give. The Mouser electronics part number is 579-MCP120-450DI/TO and the Digikey part number is MCP120-450DI/TO-ND. You can get sample quantities of the MCP120-450DI/TO from the Microchip sample program. You may request up to 5 part numbers.

December 04, 2005, at 07:24 AM by tman -- RTC can\'t auto power on because the interrupt pin is not connected
Changed lines 100-103 from:

You could add a mechanical switch in series with the output to restore the normal behavior, i.e. no auto power-on. If you try the switch approach, don't remove the existing pull-up resistor. Another option is to use software to change the behaviour of the circuit based on a bit or two in NVM (the RTC alarm registers have potential.)

In any case, I have no need for selecting a manual or software controlled power-on mode, so I haven't pursued it.

to:

You could add a mechanical switch in series with the output to restore the normal behavior, i.e. no auto power-on. If you try the switch approach, don't remove the existing pull-up resistor.

In any case, I have no need for selecting a manual controlled power-on mode, so I haven't pursued it.

December 04, 2005, at 04:34 AM by kinsa --
Changed lines 100-101 from:

You could add a mechanical switch in series with the output to restore the previous behavior, or use software to shut the unit off based on a bit or two in NVM (the RTC alarm registers have potential.) If you try the switch approach, don't remove the existing pull-up resistor. In any case, I have no need for selecting a manual power-on mode, so I haven't pursued it.

to:

You could add a mechanical switch in series with the output to restore the normal behavior, i.e. no auto power-on. If you try the switch approach, don't remove the existing pull-up resistor. Another option is to use software to change the behaviour of the circuit based on a bit or two in NVM (the RTC alarm registers have potential.)

In any case, I have no need for selecting a manual or software controlled power-on mode, so I haven't pursued it.

November 30, 2005, at 12:32 PM by dwery --
Added lines 71-77:

---

The MCP120 didn't worked on my slug. So I replaced it with another one and tried again: it worked perfectly. I guess the manufacturing process doesn't give out predicatble results.

--- dwery

November 13, 2005, at 04:34 AM by Peter --
Changed lines 25-26 from:

Note: The MCP120-450xx/TO-92 ships in four different "bondouts". Mark's solution works with the D type. If you use other packages than this (F, G or H type) Vdd, Vss and RST are on different leads! More information can be found here. I used the H type which you can order here. The picture shows the layout.

to:

Note: The MCP120-450xx/TO-92 ships in four different "bondouts". Mark's solution works with the D type. If you use other packages than this (F, G or H type) Vdd, Vss and RST are on different leads! More information can be found here. I used the H type which you can order here. The picture shows the layout.

August 24, 2005, at 09:38 PM by tman --
Changed lines 60-61 from:

Michael: with the MCP120?, the behavior is usually that the slug powers on automatically when power is applied. Apart from that, the behavior is the same as for the unmodified slug, e.g. the power button still works fine.

to:

Michael: with the MCP120, the behavior is usually that the slug powers on automatically when power is applied. Apart from that, the behavior is the same as for the unmodified slug, e.g. the power button still works fine.

Changed lines 129-138 from:

The trick is to use a microcontroller and program it to show a similar behavior as the monoflop-solution (Alternative 2). I used an Atmel ATtiny13 and quickly hacked together the program (Basic - bh - but Bascom is free in the demo version and I am lazy) to wait 2500 ms, then pull a pin low for 100 ms, release it again and then loop endless. The chip http://www.atmel.com/dyn/resources/prod_documents/doc2535.pdf costs about 1.60 Euro in single quantities (http://www.segor.de).

I used the simple programming adapter http://www.rowalt.de/mc/avr/avrboard/01/progcirc.png which draws power for the chip from the LPT. Sadly this does not work with every PC parallel port (Asus A8V does not, ancient Asus P2B works, your mileage may vary).

One drawback is that this simple hack does not power on the slug if power is lost for a short time only. The Vcc for the C must fall below about 1.8V before the power-on reset logic will trip and such trigger the power-on pulse again. You are welcome to use the chips analogue input to detect such brownouts :-)

works for me on the slugs that will not work woth the Alternative 1.

to:

The trick is to use a microcontroller and program it to show a similar behavior as the oneshot-solution (Alternative 2). I used an Atmel ATtiny13 which costs about €1.60 in single quantities and quickly hacked together the program (Basic - bh - but Bascom is free in the demo version and I am lazy) to wait 2500 ms, then pull a pin low for 100 ms, release it again and then loop endless.

I used the simple programming adapter which draws power for the chip from the LPT. Sadly this does not work with every PC parallel port (Asus A8V does not, ancient Asus P2B works, your mileage may vary).

One drawback is that this simple hack does not power on the slug if power is lost for a short time only. The Vcc for the μC must fall below about 1.8V before the power-on reset logic will trip and such trigger the power-on pulse again. You are welcome to use the chips analogue input to detect such brownouts :-)

This works for me on the slugs that will not work with Alternative 1.

August 24, 2005, at 11:28 AM by hase --
Changed lines 7-8 from:

Two solutions are offered below: The most recent is easy to build, and works for some. The second is a bit harder to build, but has been in service longer. There is insufficient evidence to show if the current two solutions are equally effective.

to:

Three solutions are offered below: The most recent is easy to build, and works for some. The second is a bit harder to build, but has been in service longer. There is insufficient evidence to show if the current two solutions are equally effective. The third solution uses a microcontroller to create solution 2 behavior with a single chip.

August 24, 2005, at 11:26 AM by hase --
Added lines 125-142:

Alternative 3

This is a variant of Alternative 2 that uses a single chip only. And no PCB.

The trick is to use a microcontroller and program it to show a similar behavior as the monoflop-solution (Alternative 2). I used an Atmel ATtiny13 and quickly hacked together the program (Basic - bh - but Bascom is free in the demo version and I am lazy) to wait 2500 ms, then pull a pin low for 100 ms, release it again and then loop endless. The chip http://www.atmel.com/dyn/resources/prod_documents/doc2535.pdf costs about 1.60 Euro in single quantities (http://www.segor.de).

I used the simple programming adapter http://www.rowalt.de/mc/avr/avrboard/01/progcirc.png which draws power for the chip from the LPT. Sadly this does not work with every PC parallel port (Asus A8V does not, ancient Asus P2B works, your mileage may vary).

One drawback is that this simple hack does not power on the slug if power is lost for a short time only. The Vcc for the C must fall below about 1.8V before the power-on reset logic will trip and such trigger the power-on pulse again. You are welcome to use the chips analogue input to detect such brownouts :-)

works for me on the slugs that will not work woth the Alternative 1.

--- hase


August 17, 2005, at 07:57 PM by blaster8 -- Success! Updated my entry on this page
Changed lines 52-55 from:

To follow up on tlhackque's comment - What is the exact behaviour of the slug with this part soldered on? What happens when the slug is shut down with the power button or through a shutdown shell command - does the slug reboot (successfully of unsuccessfully) or stay off till there is a power interruption or it is manually turned on? Thanks for your help.

PS: Thanks to hase for his excellent response - let's hope my slug is one of the lucky ones...

to:

To follow up on tlhackque's comment - What is the exact behaviour of the slug with this part soldered on? What happens when the slug is shut down with the power button or through a shutdown shell command - does the slug reboot (successfully of unsuccessfully) or stay off till there is a power interruption or it is manually turned on?

PS: Thanks to hase for his excellent response - for the record, this solution works perfectly with my NSLU2 as he describes below.

August 17, 2005, at 06:47 PM by blaster8 -- thanks to hase for answering a question
Added lines 54-55:

PS: Thanks to hase for his excellent response - let's hope my slug is one of the lucky ones...

August 10, 2005, at 09:18 AM by hase -- Alternative 1 not working always
Added lines 58-70:

Michael: with the MCP120?, the behavior is usually that the slug powers on automatically when power is applied. Apart from that, the behavior is the same as for the unmodified slug, e.g. the power button still works fine.

Problem is: I modified 20 slugs so far, Success count is 15, so one out of 5 does not automagically come on when power is applied. I am a bit lost why this is the case, so maybe someone can elaborate on the power circuit of the slug a bit; This would same me the time to reverse-engineer it :-)

For 15 slugs I see the mod to work really fine: every time that power is restored, the slug comes on and boots. The other 5 show the Power LED come one for a short time, then go off again. What timer is defying me here?

--- hase


July 30, 2005, at 07:30 PM by Michael-Luke Jones -- Question for the Alternative 1 proponents
Added lines 52-57:

To follow up on tlhackque's comment - What is the exact behaviour of the slug with this part soldered on? What happens when the slug is shut down with the power button or through a shutdown shell command - does the slug reboot (successfully of unsuccessfully) or stay off till there is a power interruption or it is manually turned on? Thanks for your help.

--- Michael


July 21, 2005, at 03:56 AM by cStyle -- copy edit
Changed lines 7-8 from:

Two solutions are offered below: The most recent is easy to build, and works for some. The second is a bit harder to build, but has been in service longer. There is insufficient evidence to show that the two current solutions are equally effective.

to:

Two solutions are offered below: The most recent is easy to build, and works for some. The second is a bit harder to build, but has been in service longer. There is insufficient evidence to show if the current two solutions are equally effective.

June 25, 2005, at 06:31 PM by tman -- Removed all old entries. Still in revision history if needed.
Deleted lines 4-5:

If you want a SLUG that will turn on when you plug it in and still allow use of the power button, you can make the first hardware modification described below. There has been a long series of attempts to make this work; to provide context, as well as credit to previous contributors, the previous howtos has been left at the end of this page. If the community accepts this version, the Previous Howto section should probably be sent to the Wiki attic.

Changed lines 9-15 from:

Howto

Alternative 1

As Edi suggests below, the Microchip MCP120-450DI/TO is a cheap, easy to implement and reliable solution. The part can be bought from Mouser electronics for $0.35 plus shipping or from Digikey for $0.43 plus shipping. For US shipment from Mouser the cheapest option in first class mail which always ends up cheaper than the estimate they give. The Mouser electronics part number is 579-MCP120-450DI/TO and the Digikey part number is MCP120-450DI/TO-ND. You can also get some free MCP120? from Microchip sample program (http://sample.microchip.com). You can get over 5 free MCP120?-450DI/TO ! So why losing money when you can get free one :-) !

to:

Howto

Alternative 1

As Edi suggests below, the Microchip MCP120-450DI/TO is a cheap, easy to implement and reliable solution. The part can be bought from Mouser electronics for $0.35 plus shipping or from Digikey for $0.43 plus shipping. For US shipment from Mouser the cheapest option in first class mail which always ends up cheaper than the estimate they give. The Mouser electronics part number is 579-MCP120-450DI/TO and the Digikey part number is MCP120-450DI/TO-ND. You can get sample quantities of the MCP120-450DI/TO from the Microchip sample program. You may request up to 5 part numbers.

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Mark

to:

--- Mark


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to:

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Edi

to:

--- Edi


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Moving the attempts prior to mine to the attic at this time would be OK with me. That would at least cut the confusion down to two.

--tlhackque

Alternative 2

to:

--- tlhackque


Alternative 2

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http://www.nslu2-linux.org/wiki/uploads/nslu2%20rework%20schematic%20v2.jpg

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http://www.nslu2-linux.org/wiki/uploads/nslu2%20rework%20v2.jpg

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http://www.nslu2-linux.org/wiki/uploads/nslu2%20pem.jpg

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http://www.nslu2-linux.org/wiki/uploads/nslu2%20pem%20installed.jpg

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Technical documentation and parts list

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Zip file with no silkscreen or soldermask layers

Zip file with silkscreen and soldermask layers (never manufactured)

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  --tlhackque

P.S. I don't endorse any of the solutions in the Previous Howto that follows...even my early attempts!

to:

--- tlhackque

Changed lines 104-245 from:

Previous Howtos

All the solutions below this line are old and not recommended for use. They are only kept to show the evolution of the force power on modification and for credits.


Old solution - Not recommended for use


Old solution - Not recommended for use

An Alternative to PCB solution

Utilises single component only

The circuit with PCB seemed like too much work. Maybe I'm just lazy :)

Seemed easier to just use a PIC. Then one can do whatever one wants. Less time and effort.

Just implemented it this afteroon and it seems to work well.

I used a PIC16F87 as I had some in my toolbox. They have an onboard RC oscillator, and although overkill, are cheap.

These PICs? are cool, simply as they need no external components to run.

I am using a 2 second on delay, with a 0.5 second trigger time.

The PIC is the only component used. :)

I only had DIP format, so it is glued to the main CPU, and fly leads used to solder it to the 74HC74.

Ground picked up of USB shield pin +5V off 74HC74 pin 14 PIC output to 74HC74 Pin4

i.e. identical points to the PEM PCB.

Ends up being quite neat and tidy, and soldering is pretty easy.

nslu2@illimitable.com

Old solution - Not recommended for use


Old solution - Not recommended for use

If you want a SLUG that will turn on when you plug it in and still allow use of the power button, do this: Connect a capacitor around 47μF (or larger. I tried with 47μF myself.) from pin 4 of the 74HC74 (The pin that connect to a 10k resistor marked with 103 on top) through a 1k resistor to the ground on the power connector. This will turn the SLUG on when you plug it in, but the power button will still work. Please note the diode is required, not optional.

P.S. I have received report from Wayne Matrejek that 22μF is too small to start NSLU2 reliably, thus I increase the capacitance value to 47μF.

Here is a picture of completed modification:

 -- Kaijuu

Old solution - Not recommended for use


Old solution - Not recommended for use

I found that even 47μF wasn't sufficient. 100μF worked for me.

One can do a neater job with surface-mount components. I used a discrete 1N456 diode; the resistor and capacitor were surface mount. A good place for the capacitor is near the text "Q11". The resistor can be mounted on the capacitor body. The leads of the diode replace all but one of the wires. (Scanned image below.) One useful trick for capacitors which have pads only on the underside is to mount them upside-down with a dab of glue. Just be careful to note which end is + first!

The circuit still isn't perfect in that a short power interruption won't reboot properly. This is because power on the board stays up for several seconds, and this doesn't allow the reset capacitor to discharge to Vil. I don't have a simple, robust fix. One note: I'm currently running diskless, so it's possible that a disk would pull down the power more quickly thru the USB port.

 -- tlhackque

Old solution - Not recommended for use


Old solution - Not recommended for use

This circuit has proven to be unreliable. Making the timer long enough to ensure reliable reset causes the software to sense the switch as still pushed-in, resulting in a maintenence mode boot. This can't be fixed with a simple tweak.

I'm working on a more complete and robust solution - will post results here. If anyone else has traced out the rest of the schematic, it would be helpful if you could post it.

 -- tlhackque

Old solution - Not recommended for use


Old solution - Not recommended for use

I had much better luck going to 100nF. Still not 100%, but close.

 -- gerti

Old solution - Not recommended for use


Old solution - Not recommended for use

I have what seems like a better solution. It's a bit more complicated, but I don't think it's worthwhile for others to keep exploring this problem. I need to get the images posted -- they've been in the queue for a while now. I don't know what the cause of the delay is.

Short form:

The previous circuit will not work reliably for any value of components. Playing with values won't improve it.

It's possible to build the improved circuit dead-bug style (images are in the posting queue), but it's rather a pain.

I've created a small printed circuit board to make it easier. (Only 8 parts, but it really IS easier!) I'll put images in the posting queue shortly.

I'll see if it's possible to post the files necessary to fabricate the PCB. The fixed cost is rather high, but at QTY 10, it gets down to the $15 range. And with effort, a good bit less. Someone (else, not me) could create a consolidated order for the community -- and should probably order the components as well.

 --tlhackque

Old solution - Not recommended for use


Old solution - Not recommended for use

I just take a look on the heading schematic, and I am a bit surprised by the 1K resistor (R6). I do not think this resistor is usefull, even worse, this is a trouble maker. The pin /PR does not go at the expected level '0' during startup time, we get in the best case 1/10 of VCC, which is reducing the duration of the seen 'PRESET' pulse. My recommended solution is to remove R6, and tune the capacitor depending on the Power Slew rate (when switch on). As I do not have such equipment (yet), If someone can do the measurement, I will be pleased to provide a capacitor value, working in 100% cases.

-- PyXpert'

Old solution - Not recommended for use


Old solution - Not recommended for use

The 1K resistor is not require for the function of the circuit, but it is required to minimize the chance of damaging the chips. When the device lost power suddenly, the large capacitor can discharge though the 74HC74 chip, the diode usually limits the amount of current going though the chip, but just for safty, an extra resistor is include to limit the peak current. It does have an undesirable effect of rising the voltage, but I did not experienced any trouble, but I might just be luckey.

I did measured the RC time required, the problem is there is a power on monitor attached to the CLEAR pin of the 74HC74 chip. The chip holds the pin low for minimum of 100mS and some chip might hold it even longer. The best solution is actually removing the chip, which is marked as Q11(I'm guessing this base on my measurement, if someone can verify this, that would be the best)

 -- Kaijuu

Old solution - Not recommended for use

to:

Previous Howtos

All of the previous attempts are not recommended for use. If you wish to view them then they are available on the history for this page.

June 25, 2005, at 04:23 PM by tlhackque -- Comments on voltage supervisor circuit
Added lines 9-10:

Two solutions are offered below: The most recent is easy to build, and works for some. The second is a bit harder to build, but has been in service longer. There is insufficient evidence to show that the two current solutions are equally effective.

Changed lines 13-14 from:
to:

Alternative 1

Changed lines 43-52 from:

Previous Howtos

All the solutions below this line are old and not recommended for use. They are only kept to show the evolution of the force power on modification and for credits.


Old solution - Not recommended for use

to:

This is a nicely packaged version of an approach that was tried & turned out not to be reliable. I found that forcing the preset input of this flip-flop when power is applied would appear to work some or most of the time. But the CPU did not reset properly -- the issue wasn't getting power on, but getting power on and getting the CPU to reset. Many time constants, including in the 150-750 msec range delivered by this part were tried. Thus, after spending quite some time instrumenting the board and analyzing the issues, I went to the 123/PCB approach, which has worked for many units over many months. The key difference is that it allows the 5V supply to become stable before turning the 3.3V supply on. It is harder to build; my focus was on rock simple, easily available components.

If someone can explain why this implemention is different from previous attempts in this family and how it allows the CPU reset to happen correctly, I'd be happy to abandon the 123 approach and endorse this one. It is not obvious to me that it does. However, while it remains empirically-based, I'm sticking with the 123/PCB solution (Alternative 2).

Moving the attempts prior to mine to the attic at this time would be OK with me. That would at least cut the confusion down to two.

--tlhackque

Alternative 2

Deleted lines 108-109:

Old solution - Not recommended for use

Added lines 111-115:

Previous Howtos

All the solutions below this line are old and not recommended for use. They are only kept to show the evolution of the force power on modification and for credits.


Added lines 118-121:

Old solution - Not recommended for use

Changed lines 193-194 from:

This circuit has proven to be unreliable. Making the timer long enough to ensure reliable reset causes the software to sense the switch as still pushed-in, resulting in a maintenence mode boot. This can't be fixed with a simply tweak.

to:

This circuit has proven to be unreliable. Making the timer long enough to ensure reliable reset causes the software to sense the switch as still pushed-in, resulting in a maintenence mode boot. This can't be fixed with a simple tweak.

June 21, 2005, at 08:15 AM by mathieu_xwave --
Changed lines 13-14 from:
to:

You can also get some free MCP120? from Microchip sample program (http://sample.microchip.com). You can get over 5 free MCP120?-450DI/TO ! So why losing money when you can get free one :-) !

June 16, 2005, at 10:05 PM by Peter --
Changed lines 22-24 from:

Note: The MCP120-450xx/TO-92 ships in four different "bondouts". Mark's solution works with the D type. If you use other packages than this (F, G or H type) Vdd, Vss and RST are on different leads! More information can be found here. I used the H type which you can order here. The picture shows the layout-

http://people.freenet.de/pennynet/nslu2.jpg

to:

Note: The MCP120-450xx/TO-92 ships in four different "bondouts". Mark's solution works with the D type. If you use other packages than this (F, G or H type) Vdd, Vss and RST are on different leads! More information can be found here. I used the H type which you can order here. The picture shows the layout.

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June 16, 2005, at 08:59 PM by Peter --
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to:

http://people.freenet.de/pennynet/nslu2.jpg

June 16, 2005, at 08:45 PM by Peter --
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Note: The MCP120-450xx/TO-92 ships in four different "bondouts". Mark's solution works with the D type. If you use other packages than this (F, G or H type) Vdd, Vss and RST are on different leads! More information can be found here. I used the H type which you can order here.

to:

Note: The MCP120-450xx/TO-92 ships in four different "bondouts". Mark's solution works with the D type. If you use other packages than this (F, G or H type) Vdd, Vss and RST are on different leads! More information can be found here. I used the H type which you can order here. The picture shows the layout-

Attach:nslu2.jpg Δ

June 16, 2005, at 07:33 PM by tman --
Changed lines 12-13 from:

As Edi suggests below, the Microchip MCP120-450DI/TO is a cheap, easy to implement and reliable solution. The part can be bought from Mouser electronics for $0.35 plus shipping or from Digikey for $0.43 plus shipping. For US shipment from Mouser the cheapest option in first class mail which always ends up cheaper than the estimate they give. The Mouser electronics part number is 579-MCP120-450DI/TO and the Digikey part number is MCP120?-450DI/TO-ND.

to:

As Edi suggests below, the Microchip MCP120-450DI/TO is a cheap, easy to implement and reliable solution. The part can be bought from Mouser electronics for $0.35 plus shipping or from Digikey for $0.43 plus shipping. For US shipment from Mouser the cheapest option in first class mail which always ends up cheaper than the estimate they give. The Mouser electronics part number is 579-MCP120-450DI/TO and the Digikey part number is MCP120-450DI/TO-ND.

June 16, 2005, at 07:33 PM by tman --
Changed lines 12-13 from:

As Edi suggests below, the Microchip MCP120-450DI/TO is a cheap, easy to implement and reliable solution. The part can be bought from Mouser electronics for $0.35 plus shipping or from Digikey for $0.43 plus shipping. For US shipment from Mouser the cheapest option in first class mail which always ends up cheaper than the estimate they give. The Mouser electronics part number is 579-MCP120-450DI/TO and the Digikey part number is MCP120-450DI/TO-ND .

to:

As Edi suggests below, the Microchip MCP120-450DI/TO is a cheap, easy to implement and reliable solution. The part can be bought from Mouser electronics for $0.35 plus shipping or from Digikey for $0.43 plus shipping. For US shipment from Mouser the cheapest option in first class mail which always ends up cheaper than the estimate they give. The Mouser electronics part number is 579-MCP120-450DI/TO and the Digikey part number is MCP120?-450DI/TO-ND.

Changed lines 22-23 from:

Note: The MCP120-450xx/TO-92 ships in four different "bondouts". Mark's solution works with the D type. If you use other packages than this (F, G or H type) Vdd, Vss and RST are on different leads! More information can be found here . I used the H type which you can order here .

to:

Note: The MCP120-450xx/TO-92 ships in four different "bondouts". Mark's solution works with the D type. If you use other packages than this (F, G or H type) Vdd, Vss and RST are on different leads! More information can be found here. I used the H type which you can order here.

Added line 50:
June 16, 2005, at 06:52 PM by Peter --
Changed lines 22-23 from:

Note: The MCP120-450xx/TO-92 ships in four different "bondouts". Mark's solution works with the D type. If you use other packages than this (F, G or H type) Vdd, Vss and RST are on different leads! More information can be found here .

to:

Note: The MCP120-450xx/TO-92 ships in four different "bondouts". Mark's solution works with the D type. If you use other packages than this (F, G or H type) Vdd, Vss and RST are on different leads! More information can be found here . I used the H type which you can order here .

June 16, 2005, at 06:43 PM by Peter --
Changed lines 11-14 from:

Note: The MCP120-450xx/TO-92 ships in four different "bondouts". Mark's solution works with the D type. If you use other packages than this (F, G or H type) Vdd, Vss and RST are on different leads! More information can be found here .

--- Peter

to:
Added lines 22-25:

Note: The MCP120-450xx/TO-92 ships in four different "bondouts". Mark's solution works with the D type. If you use other packages than this (F, G or H type) Vdd, Vss and RST are on different leads! More information can be found here .

--- Peter

June 16, 2005, at 06:41 PM by Peter --
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--- Peter

June 16, 2005, at 06:41 PM by Peter --
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Note: The MCP120-450xx/TO-92 ships in four different "bondouts". Mark's solution works with the D type. If you use other packages than this (F, G or H type) Vdd, Vss and RST are on different leads! More information can be found here .

June 08, 2005, at 01:35 AM by tman -- Rearranged page
Changed lines 5-6 from:

If you want a SLUG that will turn on when you plug it in and still allow use of the power button, you can make the hardware modification described below. There has been a long series of attempts to make this work; to provide context, as well as credit to previous contributors, the previous Howto has been left at the end of this page. If the community accepts this version, the Previous Howto section should probably be sent to the Wiki attic.

to:

If you want a SLUG that will turn on when you plug it in and still allow use of the power button, you can make the first hardware modification described below. There has been a long series of attempts to make this work; to provide context, as well as credit to previous contributors, the previous howtos has been left at the end of this page. If the community accepts this version, the Previous Howto section should probably be sent to the Wiki attic.

Changed lines 9-10 from:

Howto:

to:

Howto

As Edi suggests below, the Microchip MCP120-450DI/TO is a cheap, easy to implement and reliable solution. The part can be bought from Mouser electronics for $0.35 plus shipping or from Digikey for $0.43 plus shipping. For US shipment from Mouser the cheapest option in first class mail which always ends up cheaper than the estimate they give. The Mouser electronics part number is 579-MCP120-450DI/TO and the Digikey part number is MCP120-450DI/TO-ND .

I found the power to U15 (74HC74) glitches when the slug attempts to power down either via software or from pushing the power button. This trips the MCP120 and causes the power to not shutdown properly. I mounted the MCP120 to pick up power from the power supply jack and then ran one wire from the RST pin to R94. Connect the RST pin to the end of R94 that is also connected to U15 - pin 4 (74HC74). Here is a picture of my solution.

My slug starts up at power-on every time. And the front button still functions properly for shutdown or restart. This is much simpler to implement than the circuit board with the 74HC123A and a bunch of discrete components.

Mark


Replace the tree components with a reset controller. I used the MCP120-450DI.

Connect:

  • -RST - 74HC74 Pin4
  • -VDD - 74HC74 Pin14
  • -VSS - 74HC74 Pin7

This device will tie down the Preset of the D-flip-flop for about 350ms after power on. Should work in all conditions of power down/up.

Edi


Previous Howtos

All the solutions below this line are old and not recommended for use. They are only kept to show the evolution of the force power on modification and for credits.


Old solution - Not recommended for use

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____

to:

Old solution - Not recommended for use


Old solution - Not recommended for use

Changed lines 113-118 from:

I used a PIC16F87? as I had some in my toolbox. They have onboard RC oscillator, an although overkill, are cheap.

These PIC's are cool, simply as they need no external components to run.

I am using a 2sec on delay, with a 0.5 second trigger time.

to:

I used a PIC16F87 as I had some in my toolbox. They have an onboard RC oscillator, and although overkill, are cheap.

These PICs? are cool, simply as they need no external components to run.

I am using a 2 second on delay, with a 0.5 second trigger time.

Changed lines 121-123 from:

I only had dip format, so it is glued to the main CPU, and fly leads used to solder it to the 74HC74 . ground picked up of USB shield solder

to:

I only had DIP format, so it is glued to the main CPU, and fly leads used to solder it to the 74HC74.

Ground picked up of USB shield pin

Changed lines 127-130 from:

i.e. identical points to the PCB

Ends up being quite neat and tidy, and soldering is pretty easy

to:

i.e. identical points to the PEM PCB.

Ends up being quite neat and tidy, and soldering is pretty easy.

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Old solution - Not recommended for use

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Previous Howto:

to:

Old solution - Not recommended for use

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Old solution - Not recommended for use

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Old solution - Not recommended for use

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Old solution - Not recommended for use

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Old solution - Not recommended for use

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Old solution - Not recommended for use

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Old solution - Not recommended for use

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Old solution - Not recommended for use

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Old solution - Not recommended for use

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Old solution - Not recommended for use

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Old solution - Not recommended for use

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to:

-- PyXpert'

Old solution - Not recommended for use

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Old solution - Not recommended for use

Changed lines 233-263 from:

Replace the tree components with a reset controller. I used the MCP120-450DI.

Datasheet: http://ww1.microchip.com/downloads/en/DeviceDoc/11184d.pdf )

Connect:

  • -RST - 74HC74 Pin4
  • -VDD - 74HC74 Pin14
  • -VSS - 74HC74 Pin7

This device will tie down the Preset of the D-flip-flop for about 350ms after power on. Should work in all conditions of power down/up.

Edi

___

A SIMPLE, CHEAP, EASY SOLUTION

As Edi suggests, the Microchip MPC120-450DI/TO is a cheap, easy to implement and reliable solution. The part can be bought from Mouser electronics for $0.35 plus shipping. For US shipment the cheapest option in first class mail which always ends up cheaper than the estimate they give. The Mouser electronics part number is 579-MCP120-450DI/TO.

I found the power to U15 the 74HC74 glitches when the slug attempts to power down either via software or from pushing the power button. This trips the MPC120 and causes the power to not shutdown properly. I mounted the MPC120 to pick up power from the power supply jack and then ran one wire from the RST pin to R94. Connect the RST pin to the end of R94 that is also connected to U15 - pin 4 (74HC74). Here is a picture of my solution.

My slug starts up at power-on every time. And the front button still functions properly for shutdown or restart. This is much simpler to implement than the circuit board with the 74HC123A and a bunch of discrete components.

Mark

to:

Old solution - Not recommended for use

June 06, 2005, at 06:42 PM by Mark Smith --
Changed lines 188-191 from:

As Edi suggests the MPC120?-450DI is a cheap, easy to implement and reliable solution. The part can be bought from Mouser electronics for $0.35 plus shipping. For US shipment the cheapest option in first class mail which always ends up cheaper than the estimate they give. The Mouser electronics part number is 579-MCP120?-450DI/TO.

I found the power to the 74HC74 glitches when the slug attempts to power down either via software of from pushing the power button. This trips the MPC120? and causes the power to not shutdown properly. I mounted the MPC120? to pick up power from the power supply jack and then ran one wire from the RST pin to R94. Connect to the end of R94 that is also connected to U15 - pin 4 (74HC74). Here is a picture of my solution.

to:

As Edi suggests, the Microchip MPC120-450DI/TO is a cheap, easy to implement and reliable solution. The part can be bought from Mouser electronics for $0.35 plus shipping. For US shipment the cheapest option in first class mail which always ends up cheaper than the estimate they give. The Mouser electronics part number is 579-MCP120-450DI/TO.

I found the power to U15 the 74HC74 glitches when the slug attempts to power down either via software or from pushing the power button. This trips the MPC120 and causes the power to not shutdown properly. I mounted the MPC120 to pick up power from the power supply jack and then ran one wire from the RST pin to R94. Connect the RST pin to the end of R94 that is also connected to U15 - pin 4 (74HC74). Here is a picture of my solution.

Changed lines 194-195 from:

My slug starts up at powers on every time. And the front button still functions properly for shutdown or restart. This is much simpler to implement than the circuit board with the 74HC123A and a bunch of discrete components.

to:

My slug starts up at power-on every time. And the front button still functions properly for shutdown or restart. This is much simpler to implement than the circuit board with the 74HC123A and a bunch of discrete components.

June 06, 2005, at 06:08 PM by Mark Smith --
Added lines 186-197:

A SIMPLE, CHEAP, EASY SOLUTION

As Edi suggests the MPC120?-450DI is a cheap, easy to implement and reliable solution. The part can be bought from Mouser electronics for $0.35 plus shipping. For US shipment the cheapest option in first class mail which always ends up cheaper than the estimate they give. The Mouser electronics part number is 579-MCP120?-450DI/TO.

I found the power to the 74HC74 glitches when the slug attempts to power down either via software of from pushing the power button. This trips the MPC120? and causes the power to not shutdown properly. I mounted the MPC120? to pick up power from the power supply jack and then ran one wire from the RST pin to R94. Connect to the end of R94 that is also connected to U15 - pin 4 (74HC74). Here is a picture of my solution.

My slug starts up at powers on every time. And the front button still functions properly for shutdown or restart. This is much simpler to implement than the circuit board with the 74HC123A and a bunch of discrete components.

Mark

May 29, 2005, at 09:41 AM by nslu2illimitablecom --
Added lines 64-95:

____

An Alternative to PCB solution

Utilises single component only

The circuit with PCB seemed like too much work. Maybe I'm just lazy :)

Seemed easier to just use a PIC. Then one can do whatever one wants. Less time and effort.

Just implemented it this afteroon and it seems to work well.

I used a PIC16F87? as I had some in my toolbox. They have onboard RC oscillator, an although overkill, are cheap.

These PIC's are cool, simply as they need no external components to run.

I am using a 2sec on delay, with a 0.5 second trigger time.

The PIC is the only component used. :)

I only had dip format, so it is glued to the main CPU, and fly leads used to solder it to the 74HC74 . ground picked up of USB shield solder +5V off 74HC74 pin 14 PIC output to 74HC74 Pin4

i.e. identical points to the PCB

Ends up being quite neat and tidy, and soldering is pretty easy

nslu2@illimitable.com

Deleted line 96:

Added lines 181-185:

___

March 01, 2005, at 12:16 AM by ByronT --
Changed line 137 from:

Replace the tree components with a reset controller. I used the MCP120?-450DI.

to:

Replace the tree components with a reset controller. I used the MCP120-450DI.

February 27, 2005, at 03:32 PM by tlhackque --
Changed lines 3-7 from:

When the NSLU2 first gets power from the external power supply, it remains switched off. The following content is for people who want to change this behaviour so that the NSLU2 automatically boots when power is supplied. This might be useful if you have small power cuts every now and then, or if you want to power off your NSLU2 using an external timer...

to:

When the NSLU2 first gets power from the external power supply, it remains switched off. The following content is for people who want to change this behaviour so that the NSLU2 automatically boots when power is supplied. This might be useful if you have power failures every now and then, or if you want to power off your NSLU2 using an external timer.

If you want a SLUG that will turn on when you plug it in and still allow use of the power button, you can make the hardware modification described below. There has been a long series of attempts to make this work; to provide context, as well as credit to previous contributors, the previous Howto has been left at the end of this page. If the community accepts this version, the Previous Howto section should probably be sent to the Wiki attic.

As with any hardware modification, use at your own risk, and don't take any issues up with Linksys. It certainly voids your warranty.

Added lines 10-66:

The NSLU2 power-on sequence is more complicated than it appears. There are several hardware and software timers. The key to the power switch, as others have noted, is a 7474 flip-flop which uses the always-on 5V supply to turn on the rest of the power and trip the voltage supervisor, which ensures a proper reset for the processor. As provided by Linksys, the flip-flop powers up in the reset (cleared) state. The power switch sets it. The power switch is also readable by software, which also has a path to clear the flip-flop.

Most previous attempts to cause power to automatically turn on have attempted to assert the (otherwise unused) asynchronous preset pin of the flop longer than the existing circuitry holds the asynchronous clear pin. Various time constants have been tried. The results have been intermittent because this defeats the reset sequencer.

This version allows the normal reset sequence to occur, then electronically pushes the power-on button. It does this by detecting always-on 5V power, waiting about 2 seconds for power to stabilize and reset to occur, then using a short pulse to set the 7474 flip-flop.

This has been implemented successfully as a hand-wired circuit, as well as on a small PCB. Hand-wiring is not for the faint of heart -- or, in my case, if you have more than one unit to modify!

The only limitation is that power does have to stay off long enough for the timer to reset; if you test by unplugging the DC power cord, this can take a while. In real life, this hasn't been a problem.

Now for the details:

Circuit Schematic

http://www.nslu2-linux.org/wiki/uploads/nslu2%20rework%20schematic%20v2.jpg

You could add a mechanical switch in series with the output to restore the previous behavior, or use software to shut the unit off based on a bit or two in NVM (the RTC alarm registers have potential.) If you try the switch approach, don't remove the existing pull-up resistor. In any case, I have no need for selecting a manual power-on mode, so I haven't pursued it.

Hand-wired implementation

http://www.nslu2-linux.org/wiki/uploads/nslu2%20rework%20v2.jpg

Printed Circuit Board implementation

http://www.nslu2-linux.org/wiki/uploads/nslu2%20pem.jpg

The Power-on Enhancement Module (PEM) PCB installed

http://www.nslu2-linux.org/wiki/uploads/nslu2%20pem%20installed.jpg

The thick black wire is ground. The red wire picks up 5V from the 7474, and the white wire is the output to the preset pin.

The PEM PCB is inverted and glued upside-down onto the NSLU2 PCB. You'll want to trim a couple of component leads, and be careful not to introduce any unexpected connections. The height of the large capacitor is the critical dimension. If it is marginal, a mechanical shim between the case and the other side of the board may help to align the case.

http://www.nslu2-linux.org/wiki/uploads/nslu2%20power.pdf Technical documentation and parts list

If you want to build the Printed Circuit Boards, here are the Gerber files that I used (in .zip archives).

http://www.nslu2-linux.org/wiki/uploads/pem.zip Zip file with no silkscreen or soldermask layers

http://www.nslu2-linux.org/wiki/uploads/pemwithssandsm.zip Zip file with silkscreen and soldermask layers

Enjoy,

  --tlhackque

P.S. I don't endorse any of the solutions in the Previous Howto that follows...even my early attempts!



Previous Howto:

February 24, 2005, at 03:54 PM by Edi --
Deleted lines 85-87:
February 24, 2005, at 03:53 PM by Edi --
Changed lines 73-91 from:
 -- Kaijuu
to:
 -- Kaijuu

Replace the tree components with a reset controller. I used the MCP120?-450DI.

Datasheet: http://ww1.microchip.com/downloads/en/DeviceDoc/11184d.pdf )

Connect:

  • -RST - 74HC74 Pin4
  • -VDD - 74HC74 Pin14
  • -VSS - 74HC74 Pin7

Attach:nslu2_poweron.jpg Δ

This device will tie down the Preset of the D-flip-flop for about 350ms after power on. Should work in all conditions of power down/up.

Edi

February 21, 2005, at 03:04 AM by Kaijuu --
Changed line 71 from:

I did measured the RC time required, the problem is there is a power on monitor attached to the PSET pin of the 74HC74 chip. The chip holds the pin low for minimum of 100mS and some chip might hold it even longer. The best solution is actually removing the chip, which is marked as Q11(I'm guessing this base on my measurement, if someone can verify this, that would be the best)

to:

I did measured the RC time required, the problem is there is a power on monitor attached to the CLEAR pin of the 74HC74 chip. The chip holds the pin low for minimum of 100mS and some chip might hold it even longer. The best solution is actually removing the chip, which is marked as Q11(I'm guessing this base on my measurement, if someone can verify this, that would be the best)

February 21, 2005, at 03:02 AM by Kaijuu --
Added lines 67-68:

February 21, 2005, at 03:02 AM by Kaijuu --
Changed lines 66-71 from:
to:

-- PyXpert?' The 1K resistor is not require for the function of the circuit, but it is required to minimize the chance of damaging the chips. When the device lost power suddenly, the large capacitor can discharge though the 74HC74 chip, the diode usually limits the amount of current going though the chip, but just for safty, an extra resistor is include to limit the peak current. It does have an undesirable effect of rising the voltage, but I did not experienced any trouble, but I might just be luckey.

I did measured the RC time required, the problem is there is a power on monitor attached to the PSET pin of the 74HC74 chip. The chip holds the pin low for minimum of 100mS and some chip might hold it even longer. The best solution is actually removing the chip, which is marked as Q11(I'm guessing this base on my measurement, if someone can verify this, that would be the best)

 -- Kaijuu
February 04, 2005, at 02:05 PM by PyXpert --
Changed lines 60-66 from:
 --tlhackque
to:
 --tlhackque

I just take a look on the heading schematic, and I am a bit surprised by the 1K resistor (R6). I do not think this resistor is usefull, even worse, this is a trouble maker. The pin /PR does not go at the expected level '0' during startup time, we get in the best case 1/10 of VCC, which is reducing the duration of the seen 'PRESET' pulse. My recommended solution is to remove R6, and tune the capacitor depending on the Power Slew rate (when switch on). As I do not have such equipment (yet), If someone can do the measurement, I will be pleased to provide a capacitor value, working in 100% cases.

-- PyXpert?

January 22, 2005, at 12:57 PM by tlhackque --
Changed lines 44-60 from:
 -- gerti
to:
 -- gerti

I have what seems like a better solution. It's a bit more complicated, but I don't think it's worthwhile for others to keep exploring this problem. I need to get the images posted -- they've been in the queue for a while now. I don't know what the cause of the delay is.

Short form:

The previous circuit will not work reliably for any value of components. Playing with values won't improve it.

It's possible to build the improved circuit dead-bug style (images are in the posting queue), but it's rather a pain.

I've created a small printed circuit board to make it easier. (Only 8 parts, but it really IS easier!) I'll put images in the posting queue shortly.

I'll see if it's possible to post the files necessary to fabricate the PCB. The fixed cost is rather high, but at QTY 10, it gets down to the $15 range. And with effort, a good bit less. Someone (else, not me) could create a consolidated order for the community -- and should probably order the components as well.

 --tlhackque
January 21, 2005, at 05:55 PM by gerti --
Added lines 43-44:
 -- gerti
January 21, 2005, at 05:53 PM by gerti --
Added lines 41-42:

I had much better luck going to 100nF. Still not 100%, but close.

January 12, 2005, at 11:53 AM by tlhackque --
Changed line 24 from:

One can do a neater job with surface-mount components. I used a discrete 1N456 diode; the resistor and capacitor were surface mount. A good place for the capacitor is near the text "Q11". The resistor can be mounted on the capacitor body. The leads of the diode replace all but one of the wires. (Sorry, I don't have a digital camera to post a photo.) One useful trick for capacitors which have pads only on the underside is to mount them upside-down with a dab of glue. Just be careful to note which end is + first!

to:

One can do a neater job with surface-mount components. I used a discrete 1N456 diode; the resistor and capacitor were surface mount. A good place for the capacitor is near the text "Q11". The resistor can be mounted on the capacitor body. The leads of the diode replace all but one of the wires. (Scanned image below.) One useful trick for capacitors which have pads only on the underside is to mount them upside-down with a dab of glue. Just be careful to note which end is + first!

Added lines 29-36:
 -- tlhackque

This circuit has proven to be unreliable. Making the timer long enough to ensure reliable reset causes the software to sense the switch as still pushed-in, resulting in a maintenence mode boot. This can't be fixed with a simply tweak.

I'm working on a more complete and robust solution - will post results here. If anyone else has traced out the rest of the schematic, it would be helpful if you could post it.

December 02, 2004, at 01:14 PM by rwhitby --
Added lines 12-17:

Here is a picture of completed modification:

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Here is a picture of completed modification:

December 02, 2004, at 10:22 AM by tlhackque --
Added lines 13-21:

I found that even 47μF wasn't sufficient. 100μF worked for me.

One can do a neater job with surface-mount components. I used a discrete 1N456 diode; the resistor and capacitor were surface mount. A good place for the capacitor is near the text "Q11". The resistor can be mounted on the capacitor body. The leads of the diode replace all but one of the wires. (Sorry, I don't have a digital camera to post a photo.) One useful trick for capacitors which have pads only on the underside is to mount them upside-down with a dab of glue. Just be careful to note which end is + first!

The circuit still isn't perfect in that a short power interruption won't reboot properly. This is because power on the board stays up for several seconds, and this doesn't allow the reset capacitor to discharge to Vil. I don't have a simple, robust fix. One note: I'm currently running diskless, so it's possible that a disk would pull down the power more quickly thru the USB port.

 -- tlhackque

November 09, 2004, at 01:51 PM by Kaijuu --
Changed line 7 from:

If you want a SLUG that will turn on when you plug it in and still allow use of the power button, do this: Connect a capacitor around 22μF (or larger. I tried with 47μF myself.) from pin 4 of the 74HC74 (The pin that connect to a 10k resistor marked with 103 on top) through a 1k resistor to the ground on the power connector. This will turn the SLUG on when you plug it in, but the power button will still work.

to:

If you want a SLUG that will turn on when you plug it in and still allow use of the power button, do this: Connect a capacitor around 47μF (or larger. I tried with 47μF myself.) from pin 4 of the 74HC74 (The pin that connect to a 10k resistor marked with 103 on top) through a 1k resistor to the ground on the power connector. This will turn the SLUG on when you plug it in, but the power button will still work.

Added lines 9-10:

P.S. I have received report from Wayne Matrejek that 22μF is too small to start NSLU2 reliably, thus I increase the capacitance value to 47μF.

November 05, 2004, at 01:41 AM by tman --
Deleted lines 4-9:

Technical details:

The momentary switch is connected to an RC debounce circuit and a comparator of some sort. This combination has a single output which leads to a 74HC74D dual flip-flop which latches a high output to enable the actual power circuit.

This is why holding the power button down or messing with the comparator doesn't do anything for us - the flip-flop needs to see a state change to switch. Of course this is no problem if we just bypass all of the above and simply pull the output from the flip-flop high to begin with. :)

Changed lines 7-15 from:

So you stick a 22k resistor (probably anything between 5k and 40k would work) between the +5v line and pin 5 of the flip-flop... Et voila', auto power on!

Note that if you do this to your NSLU2 you will want to remove the power button (the translucent plastic part of it unclips easily) as this hack turns the power button into a "lock-it-up-hard" button. It seems that when the IXP420 senses the power-off interrupt it powers itself down properly internally but then needs to have a power cycle externally before it will come back up and of course we just forced power to stay on permanently!

This is no big deal though as the case still looks good without the plastic bit and a soft reboot from within the OS still works fine.

Pin 5 is circled in red and so is an existing resistor (R95) which I used as my actual connection point as it was easier to get to. R95 can be identified by the "472" inscribed upon it and the proximity to Q10.

to:

If you want a SLUG that will turn on when you plug it in and still allow use of the power button, do this: Connect a capacitor around 22μF (or larger. I tried with 47μF myself.) from pin 4 of the 74HC74 (The pin that connect to a 10k resistor marked with 103 on top) through a 1k resistor to the ground on the power connector. This will turn the SLUG on when you plug it in, but the power button will still work. Please note the diode is required, not optional.

Changed lines 10-21 from:

[http://groups.yahoo.com/group/nslu2-linux/message/827]

Updated Information:

After checking out the modification, I concluded that the picture showing the modification contain a slight error. The resistor appears to be soldered to the top (Near the 74HC74) of the 4.7k surface mount resistor (The one that has 472 written on top of it) This will have no effect as the D-FF will effectively shorted the resistor to ground. To make the modification works, it should be soldered to the bottom of that resistor (Away from the 74HC74)

BTW. resistance more than 10k is unlikely to work and resistance less than 1K will probally damage the circuit.

P.S. In the picture above, the resistor that is used looks like a 220ohm one, not a 2.2k one. With a resistance that low, it will force the D-FF high and the circuit will work, however, it will also cause the 74HC74 to overheat.

If you want a SLUG that will turn on when you plug it in, not a SLUG that stucks on (Making the power button is useless and you can't control the power through software) you probally want to try this instead: Connect a capacitor around 22μF (or larger. I tried with 47μF myself.) from pin 4 of the 74HC74 (The pin that connect to a 10k resistor marked with 103 on top) through a 1k resistor to the ground on the power connector. This will turn the SLUG on when you plug it in, but the power button will still works. Please note the diode is required, not optional.

to:
 -- Kaijuu
Deleted line 12:
November 02, 2004, at 03:56 AM by Kaijuu --
Deleted line 37:

Either add the capacitor with the diode or the 4.7k resistor, but not both!

November 02, 2004, at 03:46 AM by Kaijuu --
Added line 34:

Please note the diode is required, not optional.

Changed line 38 from:

Either the capacitor with the diode or the 4.7k resistor, but not both!

to:

Either add the capacitor with the diode or the 4.7k resistor, but not both!

November 02, 2004, at 03:44 AM by Kaijuu --
Changed line 33 from:

If you want a SLUG that will turn on when you plug it in, not a SLUG that stucks on (Making the power button is useless and you can't control the power through software) you probally want to try this instead: Connect a capacitor around 0.1μF (0.01μF to 1μF probally will work too) from pin 4 of the 74HC74 (The pin that connect to a 10k resistor marked with 103 on top) to the ground on the power connector. This will turn the SLUG on when you plug it in, but the power button will still works.

to:

If you want a SLUG that will turn on when you plug it in, not a SLUG that stucks on (Making the power button is useless and you can't control the power through software) you probally want to try this instead: Connect a capacitor around 22μF (or larger. I tried with 47μF myself.) from pin 4 of the 74HC74 (The pin that connect to a 10k resistor marked with 103 on top) through a 1k resistor to the ground on the power connector. This will turn the SLUG on when you plug it in, but the power button will still works.

Changed line 35 from:

I'm not so sure the minimum capacitance that makes the circuit works, if the slug does not turn on when you plug it in, the capacitance is probally too small.

to:
Changed line 37 from:
to:

Either the capacitor with the diode or the 4.7k resistor, but not both!

Changed lines 39-41 from:

There are two hacks on the schematic, add either the capacitor with the diode or the 4.7k resistor, but not both!

to:

Here is a picture of completed modification:

October 31, 2004, at 12:49 AM by tman --
Changed line 33 from:

If you want a SLUG that will turn on when you plug it in, not a SLUG that stucks on (Making the power button is useless and you can't control the power through software) you probally want to try this instead: Connect a capacitor around 0.1uF (0.01 to 1uF probally will work too) from pin 4 of the 74HC74 (The pin that connect to a 10k resistor marked with 103 on top) to the ground on the power connector. This will turn the SLUG on when you plug it in, but the power button will still works.

to:

If you want a SLUG that will turn on when you plug it in, not a SLUG that stucks on (Making the power button is useless and you can't control the power through software) you probally want to try this instead: Connect a capacitor around 0.1μF (0.01μF to 1μF probally will work too) from pin 4 of the 74HC74 (The pin that connect to a 10k resistor marked with 103 on top) to the ground on the power connector. This will turn the SLUG on when you plug it in, but the power button will still works.

October 31, 2004, at 12:46 AM by tman --
Changed line 3 from:

When the NSLU2 first gets power from the external power supply, it remains switched off. The following content is for people who want to change this behaviour so that the NSLU2 automatically boots when power is supplied. This might be useful if you have small power cuts every now and then, or if you want to power off your NSLU2 using an external timer ...

to:

When the NSLU2 first gets power from the external power supply, it remains switched off. The following content is for people who want to change this behaviour so that the NSLU2 automatically boots when power is supplied. This might be useful if you have small power cuts every now and then, or if you want to power off your NSLU2 using an external timer...

Changed lines 27-54 from:

After checking out the modification, I concluded that the picture showing the modification contain a slight error. The resistor appears to be soldered to the top (Near the 74HC74) of the 4.7k surface mount resistor (The one that has 472 written on top of it) This will have no effect as the D-FF will effectively shorted the resistor to ground. To make the modification works, it should be soldered to the bottom of that resistor (Away from the 74HC74)

BTW. resistance more than 10k is unlikely to work and resistance less than 1K will probally damage the circuit.

P.S. In the picture above, the resister that is used looks like a 220ohm one, not a 2.2k one. With a resistance that low, it will force the D-FF high and the circuit will work, however, it will also cause the 74HC74 to overheat.

If you want a SLUG that will turn on when you plug it in, not a SLUG that stucks on (Making the power button is useless and you can't control the power through software) you probally want to try this instead: Connect a capacitor around 0.1uF (0.01 to 1uF probally will work too) from pin 4 of the 74HC74 (The pin that connect to a 10k resistor marked with 103 on top) to the ground on the power connector. This will turn the SLUG on when you plug it in, but the power button will still works.

I'm not so sure the minimum capacitance that makes the circuit works, if the slug does not turn on when you plug it in, the capacitance is probally too small.

to:

After checking out the modification, I concluded that the picture showing the modification contain a slight error. The resistor appears to be soldered to the top (Near the 74HC74) of the 4.7k surface mount resistor (The one that has 472 written on top of it) This will have no effect as the D-FF will effectively shorted the resistor to ground. To make the modification works, it should be soldered to the bottom of that resistor (Away from the 74HC74)

BTW. resistance more than 10k is unlikely to work and resistance less than 1K will probally damage the circuit.

P.S. In the picture above, the resistor that is used looks like a 220ohm one, not a 2.2k one. With a resistance that low, it will force the D-FF high and the circuit will work, however, it will also cause the 74HC74 to overheat.

If you want a SLUG that will turn on when you plug it in, not a SLUG that stucks on (Making the power button is useless and you can't control the power through software) you probally want to try this instead: Connect a capacitor around 0.1uF (0.01 to 1uF probally will work too) from pin 4 of the 74HC74 (The pin that connect to a 10k resistor marked with 103 on top) to the ground on the power connector. This will turn the SLUG on when you plug it in, but the power button will still works.

I'm not so sure the minimum capacitance that makes the circuit works, if the slug does not turn on when you plug it in, the capacitance is probally too small.

Changed line 39 from:

There are two hack on the schematic, add either the capacitor with the diode or the 4.7k resistor, but not both!

to:

There are two hacks on the schematic, add either the capacitor with the diode or the 4.7k resistor, but not both!

October 31, 2004, at 12:34 AM by Kaijuu --
Changed lines 44-45 from:

that stuck on (Making the power button is useless and you can't control the power trhough software) you probally want to try this

to:

that stucks on (Making the power button is useless and you can't control the power through software) you probally want to try this

October 31, 2004, at 12:30 AM by rwhitby --
Changed line 56 from:

Schematic here: http://member.newsguy.com/~rhuang/10604541-L.jpg

to:
October 31, 2004, at 12:27 AM by Kaijuu --
Changed lines 23-58 from:

[http://groups.yahoo.com/group/nslu2-linux/message/827]

to:

[http://groups.yahoo.com/group/nslu2-linux/message/827]

Updated Information:

After checking out the modification, I concluded that the picture showing the modification contain a slight error. The resistor appears to be soldered to the top (Near the 74HC74) of the 4.7k surface mount resistor (The one that has 472 written on top of it) This will have no effect as the D-FF will effectively shorted the resistor to ground. To make the modification works, it should be soldered to the bottom of that resistor (Away from the 74HC74)

BTW. resistance more than 10k is unlikely to work and resistance less than 1K will probally damage the circuit.

P.S. In the picture above, the resister that is used looks like a 220ohm one, not a 2.2k one. With a resistance that low, it will force the D-FF high and the circuit will work, however, it will also cause the 74HC74 to overheat.

If you want a SLUG that will turn on when you plug it in, not a SLUG that stuck on (Making the power button is useless and you can't control the power trhough software) you probally want to try this instead: Connect a capacitor around 0.1uF (0.01 to 1uF probally will work too) from pin 4 of the 74HC74 (The pin that connect to a 10k resistor marked with 103 on top) to the ground on the power connector. This will turn the SLUG on when you plug it in, but the power button will still works.

I'm not so sure the minimum capacitance that makes the circuit works, if the slug does not turn on when you plug it in, the capacitance is probally too small.

Schematic here: http://member.newsguy.com/~rhuang/10604541-L.jpg

There are two hack on the schematic, add either the capacitor with the diode or the 4.7k resistor, but not both!

October 05, 2004, at 12:21 PM by kai --
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What is this page about:

When the NSLU2 first gets power from the external power supply, it remains switched off. The following content is for people who want to change this behaviour so that the NSLU2 automatically boots when power is supplied. This might be useful if you have small power cuts every now and then, or if you want to power off your NSLU2 using an external timer ...

Technical details:

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Howto:

September 28, 2004, at 06:16 PM by tman --
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Pin 5 is circled in red and so is an existing resistor which I used as my actual connection point as it was easier to get to. This existing resistor is not called out on the silk-screen but it can be identified by the "472" inscribed upon it and the proximity to Q10.

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Pin 5 is circled in red and so is an existing resistor (R95) which I used as my actual connection point as it was easier to get to. R95 can be identified by the "472" inscribed upon it and the proximity to Q10.

September 13, 2004, at 11:38 PM by rwhitby --
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The momentary switch is connected to an RC debounce circuit and a comparator of some sort. This combination has a single output which leads to a 74HC74D dual flip-flop which latches a high output to enable the actual power circuit.

This is why holding the power button down or messing with the comparator doesn't do anything for us - the flip-flop needs to see a state change to switch. Of course this is no problem if we just bypass all of the above and simply pull the output from the flip-flop high to begin with. :)

So you stick a 22k resistor (probably anything between 5k and 40k would work) between the +5v line and pin 5 of the flip-flop... Et voila', auto power on!

Note that if you do this to your NSLU2 you will want to remove the power button (the translucent plastic part of it unclips easily) as this hack turns the power button into a "lock-it-up-hard" button. It seems that when the IXP420 senses the power-off interrupt it powers itself down properly internally but then needs to have a power cycle externally before it will come back up and of course we just forced power to stay on permanently!

This is no big deal though as the case still looks good without the plastic bit and a soft reboot from within the OS still works fine.

Pin 5 is circled in red and so is an existing resistor which I used as my actual connection point as it was easier to get to. This existing resistor is not called out on the silk-screen but it can be identified by the "472" inscribed upon it and the proximity to Q10.

[http://groups.yahoo.com/group/nslu2-linux/message/827]

September 13, 2004, at 11:35 PM by rwhitby --
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Describe ForcePowerAlwaysOn here.

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