Goals
- Use ESP32-WROOM-32U (IPEX/U.FL module)
- AU $20 per module (ie BOM + PCB under AU $20 in Q=10 from Mouser.com / JLCPCB.com)
- No parts smaller than 0603 (Hand soldering!)
- FTDI USB <-> UART
- Battery PST PH 2.0 Connector and Charger
- Auto-program over USB
- Connect VBAT to IO via voltage divider
- Include 32k Crystal for ULP / RTC clock
- Small board - 45mm x 29mm (approx ~2 square inches)
- Breakout as many IO as possible