Arduino TPDD
There are several TPDD emulators based on the Arduino microcontroller platform.
SD2TPDD - Arduino implimentation by Jimmy Petit.
PDDuino - Fork of SD2TPDD that ports it to a few different arduino-compatible boards that have an SD card reader built-in, and adds a few enhancements like hardware sleep while idle and waking on hardware interrupt for power-saving.
Micro-TPDD-2 - Not Arduino, but using a similar microcontroller on a custom board.
arduino-tpdd - Ron Lauzon