I recently completed a project incorporating an ATXRaspi R3 with a Pi-zero. While developing the project I used a DIY bench power supply which I put together from a PC power supply. Using this PS, I've had no problems with the ATXRaspi at all - it worked as expected. I was initially using the latching LED pushbutton from LowPowerLabs.
The project takes 12VDC, goes through a MOSFET being used as reverse polarity protection, then bucks the 12V down to 5V which goes into the ATXRaspi.
The person I built this for provided his own 12V power supply. It is a S-120-12 Regulated Switching Power Supply. When I demonstrated the project everything seemed to be working fine. The next day he used the project for about 4 hours straight (just one startup/on shutdown). The day after he called indicating the project was not shutting down as I described it should. The LED on the button would not stop blinking on shutdown and he didn't know whether it was safe to shut down power (controlled by an external SPST switch).
I retrieved the project and took it home to investigate. Using my power supply, I could not duplicate the problem. I took the project back and could readily reproduce the problem. I took it back home again, thinking it was an intermittent problem somehow and I just didn't produce the right conditions to exhibit it. I checked for loose connections, bad solder joints, broken wires and found none. Just to be sure, I unsoldered the header pins on the power btn and LED through holes. Again, worked perfectly at home. Took it back, same problem. With the only difference being the power supply, we tried a different one. He happened to have a 12V battery and a 12V brick PS. With each of those the project worked fine, but would fail with the previously used PS.
The behavior with the "bad" PS was the ATXRaspi powering up WITHOUT turning on the pushbutton switch. Once the PI came up and asserted BOOT OK, SHUTDOWN would be immediately be asserted and the PI would shutdown. Instead of shutting down, it would reboot and the cycle would continue. The button LED was never really solidly on. It flickered. Actually after the second shutdown, instead of pulsing slowly, it would blink 3 times very fast, pause and repeat until the pi was done shutting down. The fact that the ATXRaspi powered on when the button was in the off position made me think there was some kind of short in the button/led header, which is why I desoldered/resoldered.
While trying to diagnose the problem, I did take measurements of voltage. The values were all in the expected range. The voltage at the ATXRaspi was 5.1V.
So, given that everything works with my bench PS, the battery and the 12V brick, I'm convinced there's nothing wrong with the ATXRaspi (or perhaps it *is* damaged somehow, but the damage is only evident with that PS).
Does anyone have ideas as to what might be causing this behavior? I don't have access to an oscilliscope, and even if I did, I don't know what I'd be looking for. But I'd suspect the power coming out of the PS is "dirty" and is somehow fooling the ATXRaspi into powering the pi even when the switch is off. Thoughts welcome.