Thoughts on PowerBus Rev 2

• Have a shunt resistor + op amp for measuring 5v usage
• Have some buttons on-board
• Include the stm32g 8x booster board? Optionally?

Uarte

Take a timer and a uarte and two gpios

Basic RX state machine:

1. Idle, but pended
   • If TX pending: goto 6
   • Else: goto 2
2. Prep Idle RX
   • Disable timer
   • Set GPIOs
   • Clear "Receiving" flag
   • Clear "Flush" flag
   • Enable RXDRDY Interrupt
   • Enable STOP interrupt
   • Start receiving with some max size
3. On First Byte
   • Verify+clear RXDRDY event
   • Disable RXDRDY interrupt
   • Set "Receiving" flag
   • Enable RXDRDY -> Timer Clear shortcut
   • Start timer
4. On Timeout
   • Disable timer
   • Set "Flush" flag
   • Trigger STOPRX event
5. On Stop
   • Check+clear end_rx
   • trigger FLUSHRX
   • Wait for Endrx
   • clear end_rx
   • goto 1
6. Start TX
7. On completion: goto 1