Python 2.x, 3.x Module for use with the adafruit RFM69HCW breakout board and the Raspberry Pi
To use this module, you no longer need to run it as root, i.e. sudo...
The module uses and relies on py-spidev and python-dev to be installed to use the SPI interface. SPI also needs to be enabled on each Raspberry Pi.
The example code also uses RPi.GPIO to set the radio enable and reset pins as well as for hardware (hw) interrupt but any python module that can manipulate the Raspberry Pi's GPIO likely could be used instead. The guide lists the functions that would require changes. I recommend starting with the txrx_example1.py
My set up consists of a RaspberryPi3 and PiZero, one running Raspbian Jessie and one running Raspbian Stretch
I'm have now used both the 433MHz and 915MHz RFM radios.
Connections to the RFM69HCW breakout board from the Pi are as follows:
- Pi MISO to Radio MISO
- Pi MOSI to Radio MOSI
- Pi SCLK to Radio SCK
- Pi CE1 to Radio CS
- Pi GPIO ## to Radio EN
- Pi GPIO ## to Radio RST
- Pi 3.3V to Radio VIN
- Pi GND to Radio GND
- Pi GPIO ## to Radio DIO0
- Radio DIO1 to DIO5 - not connected
To operate the radio (via the adafruit breakout board), the Radio EN (enable) pin has to be high (3.3V) and the Radio RST (reset) pin has to be low (GND). This module does not require the radio's hardware interrupts from DIO0 to DIO5 to operate. The radio can be operated soley on software interrupts but if other SPI peripherals are used at the same time be aware issues could arise.
This python module is set up to use the radio's FSK modulation in packet mode. I have not tried out the OOK modulation option. The module default radio settings include
- 4800 b/s
- Synch word enable
- 64 byte fixed length packets
- Encyption enabled
- checksum enabled (for trouble shooting disabling this can help)
- address filtering enabled
- 0 dBm transmit power
Tests so far have been limited to using the Pa1 amplifier stage on transmit.
The manufacture (hopeRF) instructions are invaluable and I recommend downloading a copy to aid in setting up the radio to anything beyond my defaults. These instruction can be found at www.hoperf.com/upload/rf/RFM69HCW-V1.1.pdf
Updates
May 8, 2017
- Added hardware interrupt based transmit and receive functions
- Added acknowledgement (ACK) functionality to the transmit and receive functions
- Added variable length packet capabilites in transmit and receive functions
- Added new example files including 1 to transmit a file between 2 radios (not recommended for large files, 300K files take approx 25 minutes to transmit)
March 21, 2018
- fixed SPI interface issue which surfaced after recent Pi s/w upgrades by explicitly setting speed of SPI connection
- fixed bug in acknowledgment function that caused the occassional crash
January 25, 2020
- tested out the 915MHz radio version successfully
- modified code to work with Python 3.x
- removed requirement to run program as root user, i.e. sudo...