The StompByte uses the PCM.h library running on an ATMega328p to output a duty-cycle-modulated square wave on pin 11 at 8kHz, which is connected to a 1/4" jack. Clock source is a crystal resonator, and LM7805 is used to provide a stable 5V power supply. Stomping the button triggers a sound. Holding the button for two seconds cycles through different sounds. There are 10 samples:

  1. muted kick
  2. rock kick
  3. tr808 kick
  4. woodblock
  5. cross stick
  6. tambourine
  7. handclap
  8. mario bump
  9. mario fireball
  10. mario jump

Three additional options are actually 4-step patterns. Steps 1 and 3 are triggered when the button is pressed, and 2 and 4 when the button is released.

Sounds are sampled to 8-bit PCM files, then converted to lists of 8-bit values and stored in program memory using the PROGMEM macro, using up most of the 32kb of the 328. A detailed explanation of the method can be found at MIT Media Lab's High-Low Tech blog - many thanks!

Code was written in the Arduino IDE, then the .hex file from compilation was flashed to the ATMega328p using the SPI interface on a Raspberry Pi, with the help of avrdude's linuxspi programmer option.