A Python library to detect bad power supply on Raspberry Pi. This library is mainly built for the Raspberry Pi Power Supply Checker integration of HomeAssistant. It should also work for other purpose.

This library only works on kernel 4.14 . It supports getting the under voltage bit from different entries.

Related PRs:

• raspberrypi/linux#2397: /sys/devices/platform/soc/soc:firmware/get_trottled
• raspberrypi/linux#2706: /sys/class/hwmon/hwmon0/in0_lcrit_alarm

Here is an example on how to use this library.

from rpi_bad_power import new_under_voltage

under_voltage = new_under_voltage()
if under_voltage is None:
    print("System not supported.")
elif under_voltage.get():
    print("Under voltage detected.")
else:
    print("Voltage is normal.")

Some of the code are based on custom-components/sensor.rpi_power maintained by @swetoast.