The result is a PCB with a complete transceiver controlled by an ATmega328 and sporting an OLED display, and an interesting introduction to these devices. The Si4720 internal block diagram ...

Block diagram of a 20m SSB transmitter. The first SSB transceiver I developed was for 20m, which is arguably the most fun HF band. The marine net is on 14.300. Lots of DX during the daytime hours.