Motorola MC68705P3 Projects and References

Two registers, 4Mhz operating speed, 112 Bytes of RAM, about 1KB of EPROM, and no addressing modes supporting indirection. Sometimes that’s all you need.
All code listed on this page will compile in DASM's 68705 mode unless otherwise noted.

Reference Materials:
MC68705P3 Datasheet
MC68705P3 Programming Module

Software and Tools:
MC68705P3 Equates- The equates for the microcontroller.



MC68705P3 RGB Die Roller

Completed: 4/15/2011, Build Time: Around two weeks or so.

An extremely over-engineered die roller.
The RGB segments are controlled by a 3-Channel Software PWM Driver with ~6-Bit Per-Channel accuracy (using the 68705's single timer). So you get around 18-Bit color from the RGB LEDs with a ~70Hz refresh.
Because of the PWM driver memory usage, there was only enough system stack space left for one IRQ and one JSR. Right on the edge...
The display is actually quite stable (unlike in the example video), and aside from the poor mixing in the diodes, ended up looking nice.
(Board Schematic), (ASM Source), (BIN), (Video)


MC68705P3 Clock

Completed: 1/27/2011, Build Time: A couple weeks on and off.

Puts a surprising amount of effort into keeping time.
(Board Schematic), (ASM Source), (BIN), (Video)