Introduction

CircuitPython module for the RFM95/6/7/8 LoRa 433/915mhz radio modules.

Dependencies

This driver depends on:

• Adafruit CircuitPython
• Bus Device

Please ensure all dependencies are available on the CircuitPython filesystem. This is easily achieved by downloading the Adafruit library and driver bundle.

Installing from PyPI

On supported GNU/Linux systems like the Raspberry Pi, you can install the driver locally from PyPI. To install for current user:

pip3 install adafruit-circuitpython-rfm9x

To install system-wide (this may be required in some cases):

sudo pip3 install adafruit-circuitpython-rfm9x

To install in a virtual environment in your current project:

mkdir project-name && cd project-name
python3 -m venv .venv
source .venv/bin/activate
pip3 install adafruit-circuitpython-rfm9x

Usage Example

Initialization of the RFM radio requires specifying a frequency appropriate to your radio hardware (i.e. 868-915 or 433 MHz) and specifying the pins used in your wiring from the controller board to the radio module.

This example code matches the wiring used in the LoRa and LoRaWAN Radio for Raspberry Pi project:

import digitalio
import board
import busio
import adafruit_rfm9x

RADIO_FREQ_MHZ = 915.0
CS = digitalio.DigitalInOut(board.CE1)
RESET = digitalio.DigitalInOut(board.D25)
spi = busio.SPI(board.SCK, MOSI=board.MOSI, MISO=board.MISO)
rfm9x = adafruit_rfm9x.RFM9x(spi, CS, RESET, RADIO_FREQ_MHZ)

Note: the default baudrate for the SPI is 50000000 (5MHz). The maximum setting is 10Mhz but transmission errors have been observed expecially when using breakout boards. For breakout boards or other configurations where the boards are separated, it may be necessary to reduce the baudrate for reliable data transmission. The baud rate may be specified as an keyword parameter when initializing the board. To set it to 1000000 use :

# Initialze RFM radio with a more conservative baudrate
rfm9x = adafruit_rfm9x.RFM9x(spi, CS, RESET, RADIO_FREQ_MHZ, baudrate=1000000)

Optional controls exist to alter the signal bandwidth, coding rate, and spreading factor settings used by the radio to achieve better performance in different environments. By default, settings compatible with RadioHead Bw125Cr45Sf128 mode are used, which can be altered in the following manner (continued from the above example):

# Apply new modem config settings to the radio to improve its effective range
rfm9x.signal_bandwidth = 62500
rfm9x.coding_rate = 6
rfm9x.spreading_factor = 8
rfm9x.enable_crc = True

See examples/rfm9x_simpletest.py for an expanded demo of the usage.

Documentation

API documentation for this library can be found on Read the Docs.

For information on building library documentation, please check out this guide.

Contributing

Contributions are welcome! Please read our Code of Conduct before contributing to help this project stay welcoming.