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I ran into interesting issue. I have a LED connected between 5V and GND, to indicate the board gets power (pretty common setup, I guess). What I'm looking for, it's a way to turn OFF this LED, AFTER boot.

(in fact, I'll then light up the green side of the same RGB LED using some GPIO, but that's another matter).

I cannot see any way to use RPi legs to indicate boot/finish of, primary because AFAIK I should not rely on any RPi leg during boot. Any suggestions will be welcomed. Thank you.

EDIT It's an RGB LED, the red side connected in the way described above. I'm looking for a way to turn the red off after boot, and light the same LED green, using GPIO. The question is about turning a led off, after boot.

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    " I have a LED connected between 5V and GND, to indicate the board gets power" WHY what is wrong with the PWR LED?
    – Milliways
    Dec 25, 2017 at 5:19
  • Nothing. I just would like to know the board completed boot (beyond being powered up). That's all.
    – Alex
    Dec 25, 2017 at 5:26
  • You could keep the red side of the RGB on PWR and use a script at boot to turn on the green side. The result: orange LED = booted.
    – user72982
    Dec 25, 2017 at 5:57
  • Connect the RGB LED to a 3.3V 2 to 4 decoder... something like this. The inputs of the decoder are the 3.3V line and a GPIO pin. Create a systemd service file that activates the GPIO pin... The decoder will activate 1Y1 for power and 1Y3 when boot has finished and the service file activates the GPIO pin.
    – RubberStamp
    Dec 25, 2017 at 14:45
  • Hello Whosaysbigcatsdon'twearhats and thank you for answering. Sure, it's possible, but I'd really like the red leg shut off.
    – Alex
    Dec 26, 2017 at 23:45

1 Answer 1

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Here's a partial answer... It's Christmas Day, update later if it seems helpful.

Building on my comment:

Here's the external electronic circuit to go with the proposed systemd service file [TBD]

Boot Done Indicator for Raspberry Pi

If the 74139 decoder is a 3.3V version, the left LED will be lit when power is applied to the Pi. Once the systemd service file is executed, the GPIO pin will select the right LED, and the left LED will turn off.

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  • Hello RubberStamp and thank you for answering. That's seems to be working but perhaps, a bit complicated approach. After considering the answers here and further research on the web, I think I came up with an idea, that might be simpler. I'll test it during the next few days, and come back here to update - for the benefit of the community.
    – Alex
    Dec 26, 2017 at 23:50

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