Cornichon

January 05, 2019

The Cornichon is my first attempt at a keyboard with an onboard chip. Named as such since it is kind of a gherkhin. This PCB was pretty ambitious, it features, RGB shinethrough for each key, and both PCBs, the main plate and mount plate can both double as the bottom plate, and fitting inside the 100x100mm special. I had originally wanted to have just one plate serve all three roles, but settled for two designs, and added in RGB shinethrough instead. Overall, I'm pretty happy with the way it turned out. The lack of the outside row makes some typing pains, namely backspacing, but overall, the keyboard WORKS! so that is definitely a win.

Build

Everything soldered onto the board. I made the great choice of using solder paste to solder everything, that make it much easier.

Not the prettiest solder job, but pretty good for first time. Basically all I did was spread solder paste onto the pads, then use a screw driver tip on the solder iron to heat the pins. This created bridges where there was too much solder paste, I had to use some wick to remove the extra solder. You can see on the bottom row where i accidently scraped away some of the mask on the traces. Once done I checked all the pins for continuity and made sure there were no shorts.

Success! Plugged it in and it worked first try, got it reprogramed with QMK and everything is good. I did have a minor issue with dfu not being able to see the board but some udev rules fixed that.

The switch plates with the cutouts broken out. I used some close nip shears to cut the tabs, this was very tedious, and I started to worry about damaging or dulling the cutters so eventually just tried to break them out with plyers. This was also not working great. The main thing here, I think, is just a bad design on the cutouts, I really didn't need to have two tabs on each side, next time I am just going to put one tab, so it will be easier to remove the cutouts.

All the switches put in. Novelkeys Box Royals + Kailh Box Blacks.

The switch plates soldered together, I used the nipped diode leads to connect them. I really should have left the inner column of switches out to give me more room, you can see where I melted the top left stem a bit.

Soldering the main plates together, using the switch plate as a template to get everything lined up properly.

My RGB shinethrough. The three on the top aren't working. The thing is that it is actually the second light on the row that is defective, it is not passing the color data onto the third light. This is easily debugged without special tools by simply using a wire to bypass the second light. You might also note that I was lazy with design and just have the columns wired in the datastream, the rows are mirrored.

All fixed. My RGB stategy is rather novel, I think. Instead of using plain Neopixels and trying to hand solder them as well as the bypass cap. Instead I made the PCB footprints fit the 144/meter strip from Sparkfun. These were rather easy to cut apart and hand solder. I will be using this strategy for all by future builds.

Shinethrough looks good.

Even produces some underglow.

Disaster! I didn't solder the usb port on well enough and broke it off plugging it in. Now I have to try again with the board fully assembled.

Picture of the soldering techniqe I used. The plug is then placed on top and the solder iron touched to the pins. The surface tension of the solder will draw it into the pads. The trick is to not use too much that it bridges pins.

Everything all fixed and keycaps put on. These are from a cheap corsair keyboard I bought on sale.

After several iterations I have settled on this keymap. The main pain points being the shift, and backspace keys. No outer column means no shift on pinkies, but this way the shifts are a little too far over, it is slightly uncomfortable to reach them. Backspace, is eaqually awkward, I originally put it on the raise layer under space, but that was way to awkward. Putting it under the ring finger lets me hit it with the same finger as I normally would, just down instead of up. I have had to use it a lot typing this post, and it seems like the best place for it. Less painful but still awkward is the dash, I'm used to it being on the home row, and keep hitting air when using the terminal.

Conclusion

Overall I am pleased with the cornichon, typing this post on it wasn't too painful, It should make a good travel keyboard. I am also very excited that my first try with onboard CPU worked. I am looking forward to making the Kestrel V2 with onboard chip.