How to Use Adafruit Feather RP2040 RF95 LoRa Radio: Examples, Pinouts, and Specs

The Adafruit Feather RP2040 RF95 LoRa Radio is a compact microcontroller board that combines the powerful RP2040 chip with an integrated LoRa RF95 radio module. This board is designed for long-range, low-power wireless communication, making it an excellent choice for Internet of Things (IoT) projects, remote sensing, and telemetry applications. Its small form factor and compatibility with the Feather ecosystem make it versatile and easy to integrate into a wide range of projects.

• IoT devices requiring long-range communication
• Environmental monitoring and remote sensing
• Smart agriculture and precision farming
• Asset tracking and geolocation systems
• Wireless sensor networks
• Low-power telemetry systems

• Microcontroller: RP2040 dual-core ARM Cortex-M0+ processor, running at 133 MHz
• Flash Memory: 8 MB (QSPI)
• RAM: 264 KB SRAM
• LoRa Radio Module: Semtech SX1276 (operating in the 868/915 MHz ISM band)
• Communication Range: Up to 2 km (line of sight, depending on environment)
• Power Supply: 3.3V logic, USB-C for power and programming
• Battery Support: JST connector for 3.7V LiPo battery
• GPIO Pins: 21 GPIO pins (3.3V logic)
• Interfaces: I2C, SPI, UART, ADC, PWM
• Dimensions: 51mm x 23mm x 8mm
• Weight: 5.5g

The Adafruit Feather RP2040 RF95 LoRa Radio has a standard Feather pinout. Below is a table describing the key pins:

1. Powering the Board:

   • Connect the board to a USB-C cable for power and programming.
   • Alternatively, connect a 3.7V LiPo battery to the BAT pin for portable operation.

2. Connecting the Antenna:

   • Attach a compatible LoRa antenna to the ANT connector. Ensure the antenna matches the frequency band (868/915 MHz).

3. Programming the Board:

   • Use the Arduino IDE or CircuitPython to program the board.
   • Install the necessary board definitions and libraries (e.g., Adafruit RP2040 and RadioHead libraries).

4. Interfacing with Peripherals:

   • Use the GPIO pins to connect sensors, actuators, or other peripherals.
   • For LoRa communication, connect the CS, IRQ, and SPI pins to the appropriate pins in your code.

• Antenna Placement: Ensure the antenna is securely connected and positioned away from metal objects to maximize range.
• Power Supply: Use a stable power source to avoid communication issues. If using a battery, ensure it is adequately charged.
• Frequency Compliance: Verify that the LoRa frequency (868/915 MHz) complies with local regulations.
• Heat Management: Avoid placing the board in enclosed spaces without ventilation, as the RP2040 chip may generate heat during operation.

Below is an example of how to send a simple LoRa message using the Adafruit Feather RP2040 RF95 LoRa Radio:

#include <SPI.h>
#include <RH_RF95.h>

// Define LoRa module pins
#define RFM95_CS 10  // Chip Select pin
#define RFM95_RST 9  // Reset pin
#define RFM95_INT 2  // Interrupt pin

// Frequency for LoRa communication (adjust based on your region)
#define RF95_FREQ 915.0

// Create an instance of the RF95 driver
RH_RF95 rf95(RFM95_CS, RFM95_INT);

void setup() {
  // Initialize serial communication
  Serial.begin(9600);
  while (!Serial);

  // Initialize LoRa module
  Serial.println("Initializing LoRa module...");
  pinMode(RFM95_RST, OUTPUT);
  digitalWrite(RFM95_RST, HIGH);
  delay(10);
  digitalWrite(RFM95_RST, LOW);
  delay(10);
  digitalWrite(RFM95_RST, HIGH);
  delay(10);

  if (!rf95.init()) {
    Serial.println("LoRa module initialization failed!");
    while (1);
  }

  // Set frequency
  if (!rf95.setFrequency(RF95_FREQ)) {
    Serial.println("Failed to set frequency!");
    while (1);
  }
  Serial.println("LoRa module initialized successfully.");
}

void loop() {
  // Send a test message
  Serial.println("Sending message...");
  const char *message = "Hello, LoRa!";
  rf95.send((uint8_t *)message, strlen(message));
  rf95.waitPacketSent();
  Serial.println("Message sent!");

  // Wait before sending the next message
  delay(5000);
}

1. LoRa Module Not Initializing:

   • Ensure the CS, RST, and IRQ pins are correctly connected and defined in the code.
   • Verify that the antenna is securely attached.

2. No Communication Between Devices:

   • Check that both devices are set to the same frequency and spreading factor.
   • Ensure the devices are within range and have a clear line of sight.

3. Board Not Recognized by Computer:

   • Verify that the USB-C cable supports data transfer (not just charging).
   • Check for proper installation of the RP2040 board drivers.

4. Low Signal Strength:

   • Reposition the antenna to avoid obstructions.
   • Use a higher-gain antenna if necessary.

• Can I use this board with CircuitPython?
  Yes, the Adafruit Feather RP2040 RF95 LoRa Radio is fully compatible with CircuitPython.

• What is the maximum range of the LoRa module?
  The range can reach up to 2 km in ideal conditions (line of sight).

• Can I power the board with a LiPo battery?
  Yes, the board has a JST connector for a 3.7V LiPo battery.

• Is the board compatible with other FeatherWing add-ons?
  Yes, the board follows the Feather standard and is compatible with most FeatherWings.