Arduino as ISP shield

Wrong fuses, and your board is bricked. You need an ISP programmer to get back in. This shield turns a spare Arduino Uno into one. Plug it on top. Run the ArduinoISP sketch, and avrdude flashes targets over the ICSP header. It handles the vintage AT90S1200 too, which is why I built it.

On the shield

• KiCad shield for an Arduino Uno, ICSP broken out to headers.
• Gerbers, schematic and an interactive BOM ready for fab.
• Software is stock ArduinoISP.ino with `USE_OLD_STYLE_WIRING`.
• avrdude 7.0 does the talking, under AVRDUDESS 2.14.

Using it

One Arduino programs another. Load ArduinoISP.ino, set the define, and plug the victim into the ICSP header. avrdude on the PC runs the show over USB. I went with the old-style wiring because it matches the vintage AT90S1200's pins.