Written with Gemini 2.5 so don't blame me for dodgy code, but it does seem to work well after several iterations. Allows control of an Arcam SA10 or SA20 with esphome, using a MAX3232 level shifter. I didn't need a null modem cable for this to work, just a generic adapter with a serial port on it directly into the back. just hook up 3.3v, gnd, TX, RX to the level shifter and away you go.