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!
Made a bit more progress on the pointing stick project before I realised I only have one strain gauge left. I did order more but the order got cancelled.
The mod wires went fairly smoothly, although I still hate stripping magnet wire. Haven't checked that they work - that would be a good idea because this mod is likely to be permanently glued on. Perhaps I should use hot glue to be safe.
I also printed and heavily ground away at a new mount for strain gauges.
Mutilating a keyboard and keycaps for the next prototype on the pointing stick project.
Drilling a hole for the pointing stick only cut 2 traces so it should be easy enough to fix with a couple of mod wires.
Oops, turns out my polyester resin keycaps don't like being removed with a keycap puller! The resin is too brittle :(
Anyway, I already wanted to use epoxy or polyurethane. Hopefully they'll be a bit tougher.
My new cheap hot air soldering station arrived, along with some solder paste that turned out to be leaded (I forgot to check). Tried it out and holy shit it's like magic! This is a game changer for micro USB connectors.
I tried it out on a pointing stick PCB and it's a big improvement over my dodgy hand soldering. It also saved a board I had written off because it was too much of a pain to fix the USB connector.
The keycaps should be fully cured now! They feel a little tacky when you put them against a hard surface - not sure if that's just what polyester is like.
The bottom corners weren't quite filled but the caps feel nice! Weirdly they had the texture from the original when I demoulded at 2 days, but lost it during the rest of the cure.
The long cure time and the lingering styrene smell are making me want to switch to epoxy/urethane before I do any more casting.
The pointing stick PCB is now acting as a mouse over USB. Probably should have added some pins to add buttons. Ah well, future stuff.
The plan is for this to act as an i2c peripheral. I have no idea what a normal way to do that would be. Maybe have some registers that can be written for settings, and read for position/acceleration? I also have an "interrupt out" pin that could be used when the position changes by a certain threshold?
I tried some casting! These keycaps haven't turned out perfect - the corners didn't have enough resin, not sure why. But once they're fully cured in a week they'll be cool to try out!
The moulds I've made have turned out really well but I have a long way to go with the casting. I think it would help to change to an epoxy with a mix ratio closer to 1:1, so there's not a really tiny amount of hardener to measure out.
A friend of mine from university has started selling Bluetooth speaker kits! I thought I'd give one a try, and it was a fun little build! It's a little larger than I thought it was from the pictures on his site.
There were a couple of fit issues that tend to come with 3D printed parts, but nothing that couldn't be solved with some side cutters.
I'm giving it some initial testing and so far it sounds as good as other Bluetooth speakers I've used. Not an expert on audio quality though!
Somehow the microcontroller worked first time! I got an LED blinking, so I populated the rest of the PCB, except for the non-essential stuff. Further testing will have to wait until tomorrow.
Doing the fine pitch stuff made me really wish I had a hot air soldering station. It's definitely on my wish list for next time.
It took 1.5 hours but I finally have the difficult bits soldered on! USB port, and the TQFP and TSSOP packages.
I think I'll add the bare minimum for the microcontroller and then try plugging it in.
The penny actually makes them look kinda big
Looks like the open source trackball world is starting to get some alternatives to the Ploopy!
I wanted to try casting clear resin, so I bought some moulding silicone and some clear polyethylene resin! The mould of these coins turned out pretty nice - I don't think there were any bubbles on the surface.
I put way too much catalyst in the resin so we'll see how well it cures. Apparently it's likely to crack so I'm not very hopeful. But it's only a first attempt, and I'm expecting to fail a lot!
The polyester is stinky stuff.
Aaand that's a PCB. I would check it more buuuut... yolo
Maybe on the next version I'll make sure the connectors are actually on a sensible 0.1" grid. Oh and less of a routing clusterfuck.
Successfully making more of a mess. This is what happens when you don't plan anything, just make it up as you go along.
So far the layout is just a mess but I've kinda grouped stuff to get an idea of the size needed.
I'm going for TSSOP packages, which are smaller and more of a challenge to solder than I'm used to, so that will be fun.
Schematics for the pointing stick are coming along! It still needs some tidying up but I think this is enough to get it working.
With this I can make a ~40x40mm board that can be used over USB as a trackpoint, or over i2c with a keyboard, or just output raw analog voltages.
If this works, the version after this could use the PCB itself as the beam the strain gauges are mounted to!
I got VIA pretty much working with my grid60 keyboard. It's pretty crappy how limited the documentation is, but thanks to MechMerlin's videos on youtube I got it working!
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