After some research, I settled on the PIC16F84A microcontroller from Microchip. I like this part because it doesn’t need any expensive development kit. These development kits can cost hundreds of dollars, so this represents considerable saving. The PIC16F84A is also readily available and cheap at around AU$10.

• 8 bit RISC CPU core - single cycle per instruction
• On board oscillator (external crystal required)
• Runs at any speed up to 10MHz
• Built in timer-counter
• 13 bidirectional I/O pins
• 1k FLASH memory for program
• 68 bytes of CMOS RAM
• 64 bytes of FLASH for storing data
• In-circuit programming capability

The in-circuit programming combined with the flash program memory sold me on this part. I can develop the software and test it without needing an emulator and without having to constantly swap chips in and out of a programmer or mess about with UV erasers. This should make the software development cycle fast and cheap.

On the downside, it has no serial port. I’ll have to bit-bash the serial output. Still, I’ve done this sort of thing before so it should be no problem.