Beta firmware - 0.3.0

Summary

First working demo for PCB rev 5. Not perfect, but serviceable.

What works

• Failsafe output to USB CDC serial
• OLED display + GPIO keypad user interface (UP+DOWN to exit)
• Port 80h reader
• Voltage monitor for +5V and +12V
• Info banner

To-do

• Support for PCB rev 6
• POST code database

Full Changelog: https://github.com/TheRetroWeb/PicoPOST/commits/v0.3.0