AVR demo board

One demo board per vintage AVR. That is the intent, and part of it is done. Finished so far: the AT90S1200 (1998), the 8-pin AT90S2323 and the 40-pin AT90S8535. Three boards and three firmware sets. More to come.

The three boards

• AT90S1200 board: the author's 1998 chip, on its own 20-pin PCB.
• AT90S2323 board: 128 LEDs from three I/O pins, via three shift registers.
• The 8535 board breaks every pin out to PMOD, 5 V and 3.3 V, plus a SOT-23 BOD.
• Firmware per board: blink, game of life, matrix text scroller, reaction game.

Programming them in the future

None of these chips are current, so the toolchain is half archaeology. I compile with AVR Studio 4.19 or PlatformIO, then flash over ISP with an Arduino-as-ISP shield. The AT90S2323 needs a hand-edited avrdude.conf. AVRDUDE 6.3 confuses it with the AT90S2343. Once flashed, each board runs standalone. The reaction game, for instance, is GCC assembly for a chip with no RAM.