Set GPIO Pin

[fzinken]

Check this out, I assume you can use one of the Pins that are pulled up

GPIO set to output by default on bootup?

No pins are set to output unless they are explicitly being used. Unused pins are set to input (which may appear high if no pull-up is used). See here for default pin usage: firmware/dt-blob.dts at master · raspberrypi/firmware · GitHub Which pin are you using?