I wanted to improve my assembly and "cutting-edge" PCB pool technical size limits so I've designed this board in KiCAD. It's just 20 x 15 mm PCB.
Board was made with Aisler. Here is the sharing link if you would like to manufacture PCB and stencil.
More info and pictures in these tweets:
- https://twitter.com/hubmartin/status/1266421947304476685
- https://twitter.com/hubmartin/status/1251945517552144384
This board is using 6 pin programmer. ATTiny20 is using TPI programming (instead of ISP) where MOSI pin is bi-directional. You can use USBasp programmer by Thomas Fischl, make sure you have the latest version of firmware with TPI support usbasp.2011-05-28. I've read that chinese clones use older firmwares (11 years).
You can also use Arduino to program chip. Bitluni has a great video about it.
The example code is just blinking to test that you soldered everything right. The power-switch is not controlled yet, as I did not managed to solder this 2x2 BGA correctly yet.
You compile firmware with build.sh and flash it with flash.sh. Other scripts are for ATtiny204 but that's a different project.