SD Activity LED

Has anyone added an SD activity LED to their case, or even a power LED?

I only ask as my custom case has a power switch and it would be good to know when the green light stops flashing to power off. I know I could leave it for a while but I thought it would be a nice touch.

I’m guessing I can use a couple of unused GPIO pins and edit a config file somewhere.

Would be interested to know if anyone has tried this

Edit: I guess for power I could just wire an Led with a resistor off the power switch.
I’ve just watched an online video on adding a SD led and editing config.txt - it did however say that the final flashes on shutdown did not display on the external led using this method.


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Yep, I have this working on my system.
I add the following to my “Display Config” in the webconf.


Substitute “gpio=” with the gpio line you want to wire up. The one minor drawback as you have read is that you won’t see the nice “4 blink” pattern indicating when shut down is complete. I wait until it stops blinking activity, and then add 3 seconds or more. In my mind the activity LED is better than a hardwired power indicator. I avoid removing power if the act led is still chattering so that I can avoid a corrupt SD card.

I connected a “power on” switch to GPIO 3 so that you can reboot the Zynth without having to hard cycle the power supply if you have done a shutdown. No additional configuration changes needed. Just don’t press it while Zynth is running, it interferes with the encoders.

It works very well for me. I’m hoping at some point that we’ll get an update to the Pi boot eeprom that will allow for the 4 blink shutdown indication.

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Would I have to change it to ‘dtoverlay=pi4’ if using a RP4, or does that not mater?

Does not matter at this point I think but I’ll check.

I really hate this aspect of configuration, you never really know quite what is going on and it’s so easy to develop strange areas of mythology that get handed down like religious relics … :pensive: :cold_face:

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:crazy_face: Trial and error.
“pi4” does not work. The new format, is to use “act-led” according to: linux/arch/arm/boot/dts/overlays/README at rpi-4.19.y · raspberrypi/linux · GitHub


Brilliant, thanks @smiths73v3

How did you use GPIO 17, on my list, that’s used for the touch screen.
I have a few free so all good. I test it out once I have my system back up and running.

I’m using the MIPI Pi Foundation Display, no additioal GPIO required.

You will need to pick another one. Try GPIO 4.

That is making me think I need to double check the GPIO list for my encoder adapter board epdf…