New Build: Not getting 5V or 3.3V


 
Oh wow see just when I think I know a lot about these devices, I learn something new. Thanks for the excellent explanation that allowed me to reproduce what you've seen, Ralph!

Power Port = micro USB closest to edge of board, USB Host Port = micro USB closer to the center of the board
No SD card, Power Port - Nothing
No SD card, USB Host Port - BCM2708 Boot device after ~6s
SD card with wrong image, Power Port - Nothing
SD card with wrong image, USB Host Port - Nothing
Blank SD card (no partitions), Power Port - Nothing
Blank SD card (no partitions), USB Host Port - BCM2708 Boot device immediately

The LED is a bit of a pain and I think there's a bug in the kernel driver for how it works on BCM270x. It is supposed to:
-- Blink on each SD card read as the kernel is loaded (handled by the Pi's bootloader code)
-- Blink fast once we get control of it, in preboot environment
-- Blink slowly as init scripts run
-- Steady on = fully booted

However, if I set it to steady on, it almost always is OFF on the Zeroes, and almost always ON on the full-sized Pis. I've tried a workaround of setting it to steady OFF then waiting a second then steady ON, but I still got the same results. The Zero's LED is almost certainly meant to be inverted polarity which is why it is the exact opposite of the other Pis. Because it wasn't reliable even with my code to try to force it on, I removed my extra code and just let it do what it wants and change that last step above to "Steady (on or off) = fully booted". This might be fixed in kernels later than the one we're using currently.

Also thanks, Steve, I had forgotten about gadget mode.
 
So far so good with the third Pi. Been running on 12V for the last hour or so with no issue.

I think my second Pi just suddenly died (first I obviously fried).

Just need to troubleshoot my damper now - he’s getting the voltage out the CAT5 keystone - may be a bad solder joint on the servo.

Thanks all for your help!!
 

 

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