And of course I'm posting this and then going to bed, so hopefully nothing is horribly wrong with it!

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I wrote a post about my keyboard development over the last couple of years! Not super detailed, mostly just an overview of various experiments.

gbryant.co.uk/posts/2021-04-08

@s0 Is this inspired by Adam Savage's one, or just convergent evolution?

@Tay0 Not sure if it's exactly the same principle, but pulse oximeters use a red and infrared LED shining through your finger. The oxygenated and deoxygenated blood block different amounts of the two wavelengths, and it varies as your heart beats too.

Here's a good video on those: youtube.com/watch?v=4pZZ5AEEme

I have no idea how you'd get blood pressure though - maybe it changes the "attack/decay" of the waveform of the blood flowing?

@mintey Guessing there's no option to put QMK on the current controller?

@mintey So one for input, one for output? I made one to switch between headphones and speakers but the volume control is definitely a nice touch!

@mintey That's very neat! Nice work getting all the wiring into the case.

What do the two switches switch?

anyone have suggestions for links to good PDF tutorials about writing C for embedded systems?

I've found a few whilst searching, but many are aimed at development on particular proprietary chips, I'm looking more for generic guides on how to write good code that could be ported to a variety of small computers and microcontrollers..

@dzuk On my home Linux install I have nothing on the desktop. On my work Windows laptop I have some app and file shortcuts on the desktop, but I never actually use them. So why did I bother arranging them? :thonk:

Programmed some keys on my keyboard to be mouse buttons and the pointing stick is now usable!

It's a little bit too high - I keep hitting it while typing H and I just found out that I type B with my right hand instead of my left. It would be easier not to hit it if the keyboard had a slight split.

With this longer stem on the pointing stick I am noticing drift starting to happen. That gives me a reason to look at correcting it.

Today I'll design a little nub for the top of the stick!

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@jamesvasile Will do! I don't think the current design is appropriate for anything larger scale than 5 keyboards - soldering the magnet wire to the strain gauges is too much of a pain. I need to figure out some surface mount strain gauges, which would make assembly trivial.

Unfortunately I found out that there's something wrong with the pointing stick board I soldered with the hot air station. I can't burn the Arduino bootloader on it with a setup that works for the first one I put together. Can't see anything wrong with it, so it might just be that I killed the chip while soldering it :(

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Major progress on the pointing stick project today! I actually managed to build it into a keyboard!

Started by redesigning the strain gauge mount to clear the keycaps, then printed and assembled it. That went smoothly but took a while.

It turned out the keys I bought are plate mount so they lack the little pegs that go into the PCB! But they'll do - this is just a prototype, the keys aren't the important thing here.

Initial testing feels good but it's late so I'll try it tomorrow!

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