This project enables ELRS (ExpressLRS) receivers to communicate via CRSF (Crossfire) protocol, allowing control of drones, RC vehicles, and other remote-controlled devices using an ESP32 microcontroller.
- ESP32 board
- ELRS receiver (e.g., Happymodel, BetaFPV, Radiomaster)
- RC transmitter with ELRS support
| ESP32 | ELRS Receiver |
|---|---|
| GPIO 16 (TX) | CRSF RX |
| GPIO 17 (RX) | CRSF TX |
| 5V | VCC |
| GND | GND |
The CRSF protocol is a bi-directional communication protocol used in the RC hobby community, primarily for telemetry and control data transmission. It allows for low-latency communication between the transmitter and receiver, enabling features like telemetry data, RSSI (Received Signal Strength Indicator), and more.
| Byte Index | Field | Description |
|---|---|---|
| 0 | Device Address | Identifies the sender |
| 1 | Packet Length | Total length of the packet (excluding address & CRC) |
| 2 - N | Payload Data | The actual data being transmitted (channels, telemetry, etc.) |
| N+1 | CRC | Error-checking byte (Cyclic Redundancy Check) |
For the flight controller receiver the Device Address is 0xC8, and the Packet Length is 26 bytes. The Payload Data contains the channel data, and the CRC is used to verify the integrity of the packet.
The library can read data from 16 channels, which are typically used for controlling various functions in RC devices.
| Channel | Usage | Value Range |
|---|---|---|
| 1 | Roll | 170 - 1800 |
| 2 | Pitch | 170 - 1800 |
| 3 | Throttle | 170 - 1800 |
| 4 | Yaw | 170 - 1800 |
| 5 | Arm/Disarm | 170 - 1800 |
| 6 | Flight Mode | 170 - 1800 |
| 7 - 16 | Other Assignable Channels | 170 - 1800 |
When a CRSF packet is received, the library decodes the channel data, allowing you to access it as follows:
Serial.print("Channel 1 (Roll): ");
Serial.println(channels[0]);
Serial.print("Channel 2 (Pitch): ");
Serial.println(channels[1]);
...