CRSFDude

An Arduino/PlatformIO library for building CRSF external modules on ESP32-C3. Handles half-duplex inverted UART, RC channel decoding, telemetry TX, and the EdgeTX handshake.

Blog Post — the full story of building CRSFDude, from inverted signals to frozen radios
Retro — what went well, what didn’t, lessons learned
Source Code on GitHub

Quick Start

#include "CRSFDude.h"

CRSFDude crsf;

void setup() {
    crsf.begin(20, 420000);
}

void loop() {
    if (crsf.update()) {
        uint16_t throttle = crsf.getChannel(2);
        // Link stats must be sent to enable sensor discovery
        crsf.sendLinkStats(90, 90, 100, 10, 0, 4, 3, 80, 100, 8);
        crsf.sendBattery(111, 15, 1200, 75);  // 11.1V, 1.5A, 1200mAh, 75%
    }
}

Telemetry Types

Important: sendLinkStats() with non-zero RxQuality must be sent regularly — EdgeTX silently drops all other sensors without it.

Method	EdgeTX Sensor
`sendLinkStats(...)`	RQly, RSSI, SNR, RFMD, TPWR (enables streaming)
`sendFlightMode("ACRO")`	FM (top bar)
`sendBattery(V, A, mAh, %)`	VBAT, Curr, Capa, Bat%
`sendGPS(lat, lon, spd, hdg, alt, sats)`	GPS, GSpd, Hdg, GAlt, Sats
`sendAttitude(pitch, roll, yaw)`	Ptch, Roll, Yaw
`sendBaroAltitude(cm)`	Alt
`sendVario(cm/s)`	VSpd