Toggle Led for each layer in 6x4 numpad


08 Aug 2019, 14:00

I'm a total beginner but interested in mechanical keyboards. Got myself an off the shelf one and tried my hand at making a numpad with cospad pcb. I made few mistakes with putting it together (first solderjob) but it's working. I put in 4 leds in the top row and I still need to find 4 clear keycaps to put over them. Now I was able to flash them in TMK ( and with QMK toolbox (had to figure out the driver). But I can't figure out how to make it that the first 3 led represent a layer, that light up according to which layer is active and then the 4th led for instance being the numpad on or off. Remembering I'm a complete noob, no programming history, is there someone that can point me in the right direction? I visited some websites and I see mentioning of backlight.h files etc, but using the TMK and QMK I can only flash an .eep file or a .hex file ... Anyways any info can hopefully help me in the right direction. If it's not possible to make the led toggle according with the selected layers then there's no point in me to track down clear SA keycaps (if those even exist) but it would make it a lot easier to find out which layer i'm on... Thanks for reading. :D


09 Aug 2019, 11:08

I took a quick look in QMK's source code for the Cospad. Apparently, the LEDs are not individually addressable. They are all on, or all off.

It does have four RGB LEDs for underglow though, and it would be possible to change the colour (and pattern) of those depending on what layer is active.
You would have to learn programming or find someone to do it for you though.
The programming documentation is on (Underglow is called "RGBLIGHT" in QMK for some reason ...)

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09 Aug 2019, 12:31

Fun fact: RGB LEDs are 3 LEDs in 1. Each channel is addressed independently. If you’re sneaky, you could address your LEDs as though they are colour channels of a purely virtual RGB LED!


09 Aug 2019, 14:05

Yeah in I can toggle the led in the first row and col and I can toggle the other leds all at once. So I'm not sure why I can only toggle the first one. It's also that I'm not really sure what the possibilities are with that pcb. The underglow should maybe be an option, but then I gotta find another case because the one I have is totally enclosed. I was hoping for another cospad owner who's like 600% more software savvy :) I'll check some more documentation, thanks for the link Findecanor and that virtual RGB led programming sounds plausible but no way in hell that I am the one that is gonna figure that out Muirium :)

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