Use external LED to indicate activity (heartbeat) on RPi3B+

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This topic contains 2 replies, has 1 voice, and was last updated by  FeinRib premium 2 days, 23 hours ago.

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  • 2. Dezember 2019 at 11:13 #47653

    I wired an external LED to the GPIO5 and I’m trying to
    redirect the heartbeat to this using the overlay.
    According to my research I should use:

    dtparam=pi3-act-led-trigger=heartbeat
    dtparam=pi3-act-led,gpio=5

    I hacked above code into the cmd but nothing happens.
    Then I followed this guide to make sure the LED is working at all.
    And it does. The LED is wired correctly and lights up.
    I just can’t manage to get the heartbeat working.

    Instructions are also confusing.
    Many are old, and don’t work on the P3B+.
    Some posts even state it worked on one Pi and not on the other of the same make!?
    Somewhere I found it might be related to kernel options!? Could it be?

    Will this work with the m2p image (kernel) at all and what am I doing wrong?

    2. Dezember 2019 at 11:55 #47654

    OK, found another post that seems to make more sense.

    dtoverlay=pi3-act-led,gpio=22
    dtparam=act_led_trigger=heartbeat

    Above lines seem to have no effect on the LED at runtime (when hacked to the console).
    They need to go into config.txt

    At runtime the LEDs can be controlled with the
    /sys/class/leds/led0/trigger

    Will test this later and report how it works.

    2. Dezember 2019 at 20:19 #47655

    This is how it works.
    Edit /boot/config.txt and add this:

    # Redirect activity LED to an external LED connected to GPIO5
    dtoverlay=pi3-act-led,gpio=5
    dtparam=act_led_trigger=heartbeat
    
    # Disable PWR LED
    dtparam=pwr_led_trigger=none
    dtparam=pwr_led_activelow=off

    I disabled the power LED also on that occasion.
    This thread can be considered solved.

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