Hardware Revision B

A project log for 4chord MIDI

4chord MIDI - the USB MIDI keyboard to play every major hit pop song with four little buttons.

Sven GregoriSven Gregori 07/28/2017 at 18:430 Comments

Earlier this week, the fully re-designed revision B PCBs have arrived from @oshpark, and they are even more beautiful than I imagined. You simply cannot emulate this shininess in KiCad's 3D Viewer ..or capture it on a picture, but here is one nonetheless:

The main change is obviously the PCB shape. I honestly don't know why I thought a MIDI keyboard had to be credit card sized in the first place, it's not like you'd carry it around in your wallet along with a battery powered computer to actually use it. So I figured, why not give it a more musicy look.

Also there were a few issues I didn't like in my initial design and wanted to change regarding the crystal oscillator (too high frequency for 3.3V supply voltage and a form factor which wasn't that easy to source) and the LCD (also sourcing situation, couldn't fit the back light, and they kinda kept on dying on me). Also the horizontal button arrangement for the chords playback didn't feel very ergonomic or natural.

So with the new boards designed, manufactured, and right in front of me, last night was the time to turn one of them into a functional prototype:

I emphasize prototype here, because I realized a few things along the way:

So there will be another iteration in the near future taking care of all these things, and once I'm satisfied with the results, the PCB will be available from OSH Park's shared project section, and some assembled ones will make their way to Tindie. And in the mean time, I have a whole list of new feature ideas for the firmware to work on, so I won't get bored.

(Side note on Tindie, if you'd be interested to get a 4chord MIDI keyboard, drop me a message so I could get a rough picture)