Improved on/off board
I have an improved on/off board and and have it hook up to a raspberry pi 3 and everything seems to work okay the first time. I connect switch to -in and the pi powers up I connect switch to -in again and the pi powers down gracefully but when I connect switch to -in again it powers on for about 2 seconds and then the pi powers off. If I fully remove power from the on/off board it will work again.
I did notice that about 2.3V remains on the out+ and out- pins.
Any ideas what I could be doing wrong.
FYI, I am using gpio pins 23 and 24 and have dtoverlay=gpio-poweroff,gpiopin=24,active_low="y" in my config.txt and the python script has been modified to use pin 23.
okay so after a little more investigation it seems that the when you connect the improved on/off board to the gpio pins to power the pi (pins 4 and 6 in my case) it receives a ~2V backfeed from the HDMI port (at least on the 3 monitors I tested it on) thus causing some issues with the on/off board not fully being able to eliminate power to the pi. If I power the pi over the usb header everything seems to function okay as long as I wait for the board to get below 0.6V before powering it back on.
I'm not sure what to make of the HDMI issue. The USB connector is routing power to the same parts of the board as those pins.
There's going to be a small delay before you can turn everything back on, and it's related to how long it takes for a GPIO to pull high at bootup. If you use GPIO14 you can probably reduce that delay substantially.
I'd like to get more info about what exactly the board was doing. If the HDMI is backfeeding power and keeping the GPIO pins pulled high, then the board will stay on. This is the first time I've heard of this occurring, but it's certainly possible.
You say that one was defective and having the same problem, and that the other works. If they are operating differently I would very much like to figure out why. If I send you a label, will you send the defective one to me so I can test it?