Radio Drivers

C++17 drivers for HopeRF RFM69 (SX1231/H) and RFM95/96/97/98 (SX127x) transceiver modules, designed for embedded systems and MCUs.

Features

• Hardware abstraction layer: Portable interface for SPI, GPIO, and timing
• Zero dependencies: Standard library only (C++17)
• MCU-friendly: Works on ARM Cortex-M0/M4/M7 and Unix-like systems
• Comprehensive drivers: Full support for RFM69 (FSK/GFSK/OOK) and RFM95 (LoRa)
• Test suite: Unit tests and hardware integration tests

Supported Hardware

• RFM69HCW (SX1231/H): FSK, GFSK, and OOK modulation
• RFM95/96/97/98 (SX1276/77/78/79): LoRa modulation

Quick Start

Embedded/MCU Projects

1. Implement the HAL interfaces (SpiDevice, DigitalOutPin, Timing) for your platform
2. Include the driver headers and link against the library:

#include "radio/rfm95.hpp"

// Your platform-specific HAL implementations
MySpiDevice spi;
MyDigitalOutPin csPin;
MyTiming timing;
MyDigitalOutPin resetPin;

// Configure the radio
radio::Rfm95::RadioConfig cfg{};
cfg.frequencyHz = 915000000;
cfg.modem.bandwidth = radio::Rfm95::Bandwidth::Bw125k;
cfg.modem.spreadingFactor = 7;
cfg.modem.codingRate = radio::Rfm95::CodingRate::Cr4_5;
cfg.power.powerDbm = 17;

// Initialize and use
radio::Rfm95 radio(spi, csPin, timing, &resetPin);
radio.initialize(cfg);

// Send/receive packets
std::uint8_t payload[] = {0x01, 0x02, 0x03};
radio.send(payload, sizeof(payload), std::chrono::milliseconds(1000));

std::uint8_t buffer[255];
std::size_t length;
std::int16_t rssi;
if (radio.receive(buffer, sizeof(buffer), length, 
                  std::chrono::milliseconds(5000), &rssi)) {
    // Process received packet
}

Hardware Abstraction Layer

The drivers use a minimal HAL interface defined in radio/hal.hpp:

• SpiDevice: Full-duplex SPI transfers
• DigitalOutPin: Digital output pins (chip-select, reset)
• DigitalInPin: Optional digital input pins (for DIO interrupts)
• Timing: Monotonic delays and timestamps (milliseconds)

Implement these interfaces using your platform SDK (CMSIS, Zephyr, Arduino, Linux spidev/sysfs, etc.).

RFM69 (FSK) Driver

The radio::Rfm69 class provides:

• Modulation modes: FSK, GFSK (BT 1.0/0.5/0.3), OOK
• Configurable parameters: Frequency, bitrate, deviation, RX/AFC bandwidth, sync word, packet settings, PA configuration
• Packet engine: Variable or fixed-length packets, CRC, AES encryption, address filtering
• Power control: Configurable output power up to +20 dBm (with PA boost)

See docs/radio_drivers.md for detailed API documentation.

RFM95 (LoRa) Driver

The radio::Rfm95 class provides:

• LoRa modulation: Bandwidth (7.8 kHz - 500 kHz), spreading factor (SF6-SF12), coding rate
• Modem configuration: CRC, IQ inversion, symbol timeout, preamble length, sync word
• Power control: Configurable output power up to +20 dBm
• RSSI and SNR: Automatic signal quality reporting

See docs/radio_drivers.md for detailed API documentation.

Building

CMake

cmake -S . -B build
cmake --build build -j$(nproc)

Make

make build

Testing

Run the test suite:

cd build
ctest --output-on-failure

Or run individual tests:

./build/rfm69_modulation_tests
./build/radio_hardware_tests  # Requires physical hardware

Hardware Tests

The radio_hardware_tests require physical RFM69/RFM95 modules connected via SPI and GPIO. Set environment variables to configure the test:

export RADIO_HW_RFM69_A_SPI=/dev/spidev0.0
export RADIO_HW_RFM69_A_CS=/sys/class/gpio/gpio25
export RADIO_HW_RFM69_A_RESET=/sys/class/gpio/gpio24
export RADIO_HW_RFM69_B_SPI=/dev/spidev0.1
export RADIO_HW_RFM69_B_CS=/sys/class/gpio/gpio27
export RADIO_HW_RFM69_B_RESET=/sys/class/gpio/gpio23
./build/radio_hardware_tests

Documentation

• docs/radio_drivers.md: Detailed driver documentation and API reference
• RF_docs/: Datasheets for RFM69 and RFM95 modules

License

MIT License - see LICENSE file for details.