This dates back to 1986 when I built the first FSM controller using discrete CMOS logic. It ran the local repeater for a while, and I was given a merit award for it by the local club.

Since then it has been migrated to an FPGA, and other functions such as DTMF decoders have been integrated. The first version used an evaluation module with a piggy-back board for repeater interfacing, the second has been realized as a HAT (hardware attached on top) for the raspberry pi.

The pi HAT version is continuing to evolve with more additions such as expansion ports and remote telemetry in development, more on that as it evolves.