433.92 MHz RF communication on Raspberry Pi

rfctl is a simple Linux driver and control tool for 433.92 MHz RF communication on Raspberry Pi.

The following guide assumes the Raspbian Linux distribution is used on the Raspberry Pi. However, the kernel driver and the rfctl tool should work fine on any distribution with a relatively modern kernel.

The following formum topic, although dated, also covers this driver and provides some helpful tips and discussions.

• https://www.raspberrypi.org/forums/viewtopic.php?t=11159

rfctl driver

The default control interface of the rfctl tool utilizes rfctl.ko. It is a LIRC style kernel device driver transmitting and recording pulse and pause lengths by bit banging on a GPIO pin. See HARDWARE.md for information on how to connect the GPIO to a common 433 MHz TX module.

To build you first need to install the kernel headers, in Raspbian the raspberrypi-kernel-headers meta package points to the latest kernel headers, which will install somewhere in /lib/modules:

sudo apt install raspberrypi-kernel-headers

Then enter the kernel driver directory to build, load the driver, and create the device node rfctl uses:

cd rfctl/kernel
make
sudo make insmod

rfctl tool

rfctl is a small tool that acts as a remote control for switches that use simple unidirectional communication based on OOK (On Off Keying) modulation on a 433 MHz carrier. By default rfctl uses the Linux rfctl.ko kernel driver.

To build:

cd rfctl/src
make
sudo make install

A simple test on an old style (not selflearning) NEXA/PROVE/ARC set to group D, channel 1.

rfctl -p NEXA -g D -c 1 -l 1
rfctl -p NEXA -g D -c 1 -l 0

Some popular (cheap) noname RF sockets, available from e.g. Conrad (DE), Kjell & C:o (SE), or Maplin (UK) use the SARTANO/ELRO protocol and need to be encoded like this:

rfctl -p SARTANO -c 1000100000 -l 1     # I - 1
rfctl -p SARTANO -c 1000010000 -l 1     # I - 2
rfctl -p SARTANO -c 1000001000 -l 1     # I - 3
rfctl -p SARTANO -c 1000000100 -l 1     # I - 4

rfctl -p SARTANO -c 0100100000 -l 1     # II - 1
rfctl -p SARTANO -c 0100010000 -l 1     # II - 2
rfctl -p SARTANO -c 0100001000 -l 1     # II - 3
rfctl -p SARTANO -c 0100000100 -l 1     # II - 4

rfctl -p SARTANO -c 0010100000 -l 1     # III - 1
rfctl -p SARTANO -c 0010010000 -l 1     # III - 2
rfctl -p SARTANO -c 0010001000 -l 1     # III - 3
rfctl -p SARTANO -c 0010000100 -l 1     # III - 4

rfctl -p SARTANO -c 0001100000 -l 1     # IV - 1
rfctl -p SARTANO -c 0001010000 -l 1     # IV - 2
rfctl -p SARTANO -c 0001001000 -l 1     # IV - 3
rfctl -p SARTANO -c 0001000100 -l 1     # IV - 4

Issue rfctl --help to get more information on supported protocols and options.

Note: All protocols might not be fully tested due to lack of receivers and time :)

there are four lights

As an example of how to automate your home, there is a small script included that can be set up to run from cron. For details, see the script header comments in onoff.sh it also has optional support for the Pimoroni Firefly Light, this because the author has a small Raspberry Pi Zero at home.

disclaimer

Do not use this software in situations where operation of, or lack of operation, may result in property damage, personal injury, or death. Regulatory bodies may have locked down public use of RF communication in your location at a national level. Do not use the rfctl software to break applicable laws and regulations.

origin & references

This project orignates from the rf-bitbanger project which was created by Tord Andersson. It is released under the GNU General Public License (GPL), version 2. See the file COPYING for details.

Code fragments from rfcmd by Tord Andersson, Micke Prag, Gudmund Berggren, Tapani Rintala, and others. The kernel driver, rfctl.ko, is based on lirc_serial.c by Ralph Metzler et al.