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Any settings to hold pi from booting with a GPIO pin?

Posted: Wed Sep 04, 2019 9:32 pm
by liudr
I'm interested in running a pi 0w on a computer USB port with power running through an arduino that acts as a USB device. I could add a transistor to turn on PI when arduino finishes USB enumeration so it could receive 500mA. But instead, if there is a setting I can enable to hold pi in a kind of reset/powered down mode by applying 0V or 3.3V to a pi pin, that would be easier. I know there's an overlay to shut down pi if a certain pin is set or reset. What about a general reset pin like a microcontroller? Will the shutdown pin overlay keep the pi in a shutdown state that won't generate a spike on the USB power rail? Thanks.

Re: Any settings to hold pi from booting with a GPIO pin?

Posted: Thu Sep 05, 2019 10:12 am
by rpdom
There is the RUN header on the Pi Zero. Connecting the RUN pin 1 to 0V will hold the Pi in a Halt state until it is released. That won't stop the Pi using some power, but it will stop it from running and reduce the power a bit.