I have a GPS receiver connected to a Pi, with 1PPS input connected to GPIO4. This GPS module does not have a PPS or lock LED, so I would like to have it indicate with the activity LED. Based on the output of cat /sys/devices/platform/leds/leds/led0/trigger I see that "gpio" is a trigger option, but I don't see how to declare which GPIO is used!

I have been looking through ledtrig-gpio.c to figure out what syntax it wants but I haven't made any progress so far.

For what it's worth, I am using a Pi 3b+ with DietPi (Debian Buster).


  • Read through /boot/overlays/README and search for act_led_gpio Feb 9, 2021 at 21:57
  • Hm, I don't think this is what I am looking for - act_led_gpio seems to be the GPIO pin that you redirect the "activity" behavior to a GPIO pin so you could use an external LED instead of the onboard one. What I want to do is have the activity LED reflect the state of a GPIO pin (e.g. GPIO high = LED lit).
    – millerjs
    Feb 11, 2021 at 0:13
  • Oh, I misunderstood Feb 11, 2021 at 0:27
  • No worries - I know what I'm asking is a little bit strange, but according to the documentation, it can be done!
    – millerjs
    Feb 12, 2021 at 1:01
  • according to the documentation - which documentation? Feb 12, 2021 at 1:13


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