I may need to add a CPU to a design I am doing. I had rolled my own core once with a 16 bit data path and it worked out fairly well. But it was 600 LUT/FFs and I would like to use something smaller if possible. The target is a Lattice XP3 with about 3100 LUT/FFs and about 2000 are currently used. I believe that once I add the CPU core, I can take out a lot of the logic since it runs so slowly. The fastest parallel data rate is 8 kHz with some at 1 kHz and the rest at
100 Hz. I probably would have used a CPU to start with instead of the FPGA, but there was a possible need to handle higher speed signals which seems to have gone away.I recall that someone had started a thread about serial implementations of processors that were supported by a C compiler. I don't think any ever turned up. But the OP had some other requirements that may have excluded a few very small designs. Are there any CPU cores, serial or parallel, that are significantly smaller than 600 LUT/FFs? The Lattice part has LUT memory even dual port, so that is not a constraint, the LUTs can be used for registers.
Rick