The OLED Face

Published on 2022-12-31 in Moo Bug.

The PCBs arrived right after the holidays, and I quickly assembled one, moved the whole legs from one of my fluffbugs, and here it is, all working as expected. I just had to update the pin names in my circuitpython code, that’s literally it. But then I decided to try and get to work one of the shields – the one with a display and a speaker.

The display just worked. I used the SH1106 library for displayio, and I just had to rotate the display 180° and add a 2-pixel horizontal shift to adapt it to this particular display. I got really good with that working on all those handheld game consoles.

The speaker turned out to be a bit more challenging. I used a MAX98357A I2S amplifier, because I had that on a module earlier and I was confident it works well. Well, despite the schematic being practically the same with the module (minus some unnecessary caps, as usual), this one didn’t work. The chip is a bit small QFN package, but visually it looked soldered well. I tried a lot of different things, until at fifth re-soldering of the chip with the hot-air gun, it suddenly started working. I suppose looking good is not enough. Of course with such a tiny speaker the quality is questionable, but it does sound properly robotic, and it’s surprisingly loud (I hardwired the amplifier to maximum gain).