I connected several devices to my raspberry pi Zero. These devices are breakout boards for sensor and some ICs. Sometimes I suspect that one of the boards has short circuit. For example, when I modify wiring and flux residue is not cleaned properly. Thus I wanted to know, if it's possible to check whether the Pi Zero has been booted, by measuring a voltage of a node. This is for protecting my PC. Unfortunately I do not have a monitor in the location.

I disabled LED using the boot script and may not enable it again, because the place should be completely dark, except when I go there to deal with the hardware.


If you aren't otherwise using the Pi's serial pins, you could connect a USB-to-Serial adapter onto those pins (like this one from Adafruit) to access a terminal from another computer like a laptop. If the Pi is booted, you'll get a console over the serial port.

If your Pi is a Pi Zero W or has a USB network adapter, you could check whether it is booted by monitoring it's connection to the network (using an app like fing). Just do a network scan, and the Pi will only show up if it has booted.


If you rule out most of the options, then you have to consider the few that are left. You said you don't want to use USB or HDMI, but are you sure you can't use those? If you haven't used all the GPIO pins then those are a possible option to run a script at boot time and read off that voltage. Another, depending on your skills would be to re-enable the LED but remove it and read the voltage from its leads. The last two I can think of are the composite video out (the two pads marked TV), and the pads marked run.

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