M-bus to USB board

• KiCAD 6.X required
• includes ESD (USB+MBUS) and TVS (MBUS) protections
• includes AP3015 stepup from 5V -> 34V
• includes CH340E UART IC

Software

Tested with https://github.com/ganehag/pyMeterBus library.

5V vs 3.3V note

CH340E is 5V only IC without additional 3.3V regulator. Even its RX/TX pins are 5V. Use PL2303GL instead when CH340E is not available and change MBUS logic to 3.3V (replace R6 and R10).

Board overview