Function Generator on a PI Pico.

Development + Debug environment:
- VSCode on Win 7
- Picoprobe running on 2nd RPI pico
- OpenOCD and GDB
Rotary encoder input using State Machine 0
Onboard LED flashing using State Machine 1
Nixie tube display
- Multiplexed to reduce hardware
- 170 volt PSU for tubes created from 4 x 1.5v batteries + custom SMPS
8 bit R2R ADC creating Sine wave output for oscilloscope