Stuff I would like to address in the future:
- Move the power supply inside. This would allow tapping the transformer at multiple points to get different voltages for the logic and the debiased transistor.
- Switch to a more powerful MCU that supports more sophisticated code. The RS-232 UART code really should be on a timer interrupt, a built-in pseudorandom number generator would be nice if it isn't too processor-intensive, etc.