I am running Ubuntu Mate on a Raspberry Pi 2B.

I would like to find which GPIO pin is currently used for the heartbeat, i.e. activity, so I can attach an external LED.

The config.txt entry is like so:

## act_led_gpio
##     Set which GPIO to use for the activity LED
##     In case you want to connect it to an external device
##     Default 16 on a non-Plus board, 47 on a Plus or Pi 2.

There are only forty pins, so it can't be physical pin 47, or the GPIO BCM numbering. Does anyone know which system is used here?


It is BCM and 47 is only internal and control the activity LED. All GPIO isn't populated out to the 2x20 pin header.

To use an external LED just redefine dtparam=act_led_gpio=47 to something of your liking, example:


And place a LED on pin 16 (GPIO23) with appropriate resistor.

PS. and remove the # in the beginning.

  • #Yes I will, wouldn't work great otherwise! Just a question, will setting it to anything else disable the inbuilt act LED?
    – user72982
    Jan 15 '18 at 16:58
  • Well not anything, but yes you redirect dtparam=act_led_gpio from default 47 to another destination, like 23 in my example. But to use a random number isn't recommended, you could get a conflict!
    – MatsK
    Jan 15 '18 at 17:06
  • 1
    Sorry, I could have said it more clearly, I was asking if changing the pin would disable the act LED on the board.
    – user72982
    Jan 15 '18 at 17:11
  • Yes it does. You are telling the the Raspberry to NOT use 47 and to use another one instead.
    – MatsK
    Jan 15 '18 at 17:16

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