How to Use ELRS/Crosfire Receiever Radiomaster RP1: Examples, Pinouts, and Specs

The Radiomaster RP1 is a high-performance receiver designed for long-range control in RC (Radio Control) applications. It is compatible with both ELRS (ExpressLRS) and Crossfire protocols, making it a versatile choice for hobbyists and professionals alike. The RP1 offers low latency, robust signal reliability, and excellent range, making it ideal for drones, RC planes, and other remote-controlled devices.

• Long-range FPV (First Person View) drones
• RC planes and helicopters
• Remote-controlled cars and boats
• Robotics and automation projects requiring reliable wireless communication

The Radiomaster RP1 is engineered to deliver exceptional performance in demanding environments. Below are its key technical specifications:

The Radiomaster RP1 features a simple pinout for easy integration into your projects. Below is the pin configuration:

1. Power Connection: Connect the 5V pin to a 5V power source and the GND pin to ground.
2. UART Connection: Connect the TX pin of the RP1 to the RX pin of your flight controller, and the RX pin of the RP1 to the TX pin of your flight controller.
3. Antenna Installation: Attach the included antenna to the IPEX connector. Ensure the antenna is securely connected to avoid signal loss.
4. Binding: Follow the binding procedure for your chosen protocol (ELRS or Crossfire). For ELRS, use the ExpressLRS Configurator to set up the receiver and transmitter.

• Antenna Placement: Ensure the antenna is positioned away from metal components and other electronics to minimize interference.
• Firmware Updates: Keep the firmware up to date using the Over-the-Air (OTA) method or USB to ensure optimal performance and compatibility.
• Power Supply: Use a stable 5V power source to avoid damage to the receiver.
• Protocol Selection: Ensure your transmitter is set to the same protocol (ELRS or Crossfire) as the receiver.

If you are using the Radiomaster RP1 with an Arduino UNO for a custom RC project, you can use the following example code to establish communication:

#include <SoftwareSerial.h>

// Define RX and TX pins for the Arduino
#define RX_PIN 10  // Connect to RP1 TX pin
#define TX_PIN 11  // Connect to RP1 RX pin

// Initialize SoftwareSerial for communication with the RP1
SoftwareSerial RP1Serial(RX_PIN, TX_PIN);

void setup() {
  // Start serial communication with the RP1
  RP1Serial.begin(115200); // Set baud rate to match the RP1
  Serial.begin(9600);      // For debugging via Serial Monitor

  Serial.println("Radiomaster RP1 Receiver Initialized");
}

void loop() {
  // Check if data is available from the RP1
  if (RP1Serial.available()) {
    String receivedData = RP1Serial.readString();
    Serial.print("Data from RP1: ");
    Serial.println(receivedData);
  }

  // Example: Send data to the RP1
  RP1Serial.println("Hello RP1");
  delay(1000); // Wait 1 second before sending again
}

• Ensure the baud rate in the code matches the configuration of the RP1.
• Use appropriate level shifters if your Arduino operates at 5V logic levels, as the RP1 may use 3.3V logic.

1. Receiver Not Binding to Transmitter

   • Ensure both the receiver and transmitter are set to the same protocol (ELRS or Crossfire).
   • Check that the firmware versions of the receiver and transmitter are compatible.
   • Follow the binding procedure carefully, ensuring the receiver is in binding mode.

2. Poor Signal Range

   • Verify that the antenna is securely connected and properly positioned.
   • Avoid placing the receiver near sources of interference, such as motors or ESCs.
   • Check for damage to the antenna or receiver.

3. No Communication with Flight Controller

   • Double-check the UART connections (TX to RX and RX to TX).
   • Ensure the correct UART port is enabled in your flight controller's configuration software (e.g., Betaflight).

4. Firmware Update Fails

   • Ensure the receiver is powered correctly during the update process.
   • Use a stable USB connection or reliable OTA method.
   • Verify that the firmware file is correct for the RP1.

Q: Can I use the RP1 with a 3.3V power source?
A: No, the RP1 requires a 5V power source for proper operation.

Q: How do I switch between ELRS and Crossfire protocols?
A: The protocol is determined by the firmware loaded onto the receiver. Use the appropriate firmware for your desired protocol.

Q: What is the maximum range of the RP1?
A: The RP1 can achieve a range of up to 15 km, depending on environmental conditions and antenna placement.

Q: Can I use the RP1 with other transmitters besides Radiomaster?
A: Yes, as long as the transmitter supports ELRS or Crossfire protocols, it will be compatible with the RP1.