Hardware Setup
This section describes how to connect the RP2040 board to your receiver and sensors.
The wiring can be visualized in the Circuit tab of MSRC Link.
The RP2040 must be connected to the PC to display the circuit.
The table below shows the default GPIO assignments.
Note: These are RP2040 GPIO numbers, which are the same for all boards.
Physical pin numbers vary depending on the board (RP2040 Zero, Pico, etc.).
| Function / Sensor | GPIO |
|---|---|
| Power (3.3–5V) | 5V |
| GND | GND |
| SmartPort, SBUS, SRXL, IBUS, SB, Jeti EX, Sanwa, HoTT, SRXL2, FPort, FBUS, GHST | 0 (1) & 1 |
| FrSky D, ELRS / CRSF RX | 0 |
| Serial monitor | 1 |
| Hitec / XBUS SDA | 2 (2) |
| Hitec / XBUS SCL | 3 (2) |
| ESC serial, Serial monitor, Smart ESC | 5 |
| Phase sensor (PWM input), Smart ESC | 4 |
| Castle receiver signal | 4 |
| Castle ESC signal | 5 (2) |
| GPS TX | 6 |
| GPS RX | 14 |
| XBUS NPN clock stretch (3) | 7 |
| Sensor SDA | 8 (2) |
| Sensor SCL | 9 (2) |
| PWM output | 10 |
| Fuel meter (PWM input) | 11 |
| Smart ESC throttle | 12 |
| Smart ESC reverse | 13 |
| Restore default configuration | 15 |
| Analog voltage | 26 |
| Analog current | 27 |
| Temperature (NTC) | 28 |
| Airspeed | 29 |
| General GPIOs | 17–22 |
(1) A 100Ω resistor is recommended.
This is optional, as the RP2040 includes internal protection resistors.
(2) Pull-up resistors are required.
See protocol-specific documentation for details (e.g. XBUS, Hitec).
The RP2040 must be powered with 3.3V to 5V.
Power can be supplied from:
- Receiver telemetry port
- BEC (Battery Eliminator Circuit)
Some receivers provide a regulated 5V output on the telemetry port even if the main BEC voltage is higher. Always verify the voltage before connecting.
If your system operates above 5V, a voltage regulator is required.
The onboard LED blinks when telemetry is being transmitted.
- If the LED is blinking → telemetry is active
- If the LED is not blinking → check wiring and configuration
RP2040 board pinouts:
RP2040 Zero pinout
RP2040 Pico pinout