RCSwitchFirmata

Dependencies

ConfigurableFirmata 2.10.0 RCSwitch 2.5.2 perl-firmata 0.63 fhem with support for Firmata > 2.6 fhem-mirror/dev

Description

RCSwitchFirmata is an Arduino sketch that combines ConfigurableFirmata and rc-switch. It comes with an integration into FHEM.

RCSwitchFirmata allows you to use a single Arduino for multiple purposes, including radio transmissions. For example, you can read digital inputs, control a relais and switch radio outlets with a single Arduino today. You could extend that to receive the temperature from your weather station tomorrow, without a change to the Arduino sketch.

Firmata is a protocol for communicating with microcontrollers from software on a host computer. ConfigurableFirmata is a plugin-based version of Firmata which allows to read and control an Arduino from a host computer without changes to the Arduino firmware.

rc-switch is a library for sending and receiving signals to radio controlled devices.

Hardware configuration

Requirements

• Any host machine (e.g. your computer)
• Any Arduino (e.g. an Arduino Nano)
• Any RF sender to send RF signals (e.g. FS1000A)
• Any RF receiver to receive RF signals (e.g. RXB6)

Setup

1. Connect the sender to an arbitrary pin.
2. Connect the receiver to a pin that supports interrupts (depending on your Arduino model, usually pins 2 & 3).
3. Connect the Arduino to the host.

Arduino configuration

Requirements

• Arduino IDE
• Directory arduino/libraries from this project

Setup

1. Copy the content of the project directory arduino/libraries into your Arduino library folder.

• On Windows and Mac, this is the Documents folder in your user home directory, e.g. My Documents/Arduino/libraries
• On Linux, this is Sketchbook/libraries in your user home directory.

1. Open the RCSwitchFirmata sketch in the Arduino IDE and configure it according to your needs.
2. Upload the sketch to your Arduino.

Firmata features can be en-/disabled by in-/excluding the corresponding header in the RCSwitchFirmata sketch.

FirmataExt

FirmataExt must be enabled because it is required for communication between host and Arduino. It is enabled by default:

#include <utility/FirmataExt.h>
FirmataExt firmataExt;

RCOutputFirmata

RCOutputFirmata is required to send. It is enabled by default:

#include <RCSwitch.h> //wouldn't load from RCOutputFirmata.h in Arduino1.0.3
#include <utility/RCOutputFirmata.h>
RCOutputFirmata rcOutput;

RCInputFirmata

RCInputFirmata is required to receive. It is enabled by default:

#include <RCSwitch.h> //wouldn't load from RCInputFirmata.h in Arduino1.0.3
#include <utility/RCInputFirmata.h>
RCInputFirmata rcInput;

Other Firmata features

You may disable any Firmata feature to save memory. For example, if you don't need analog outputs:

//#include <utility/AnalogOutputFirmata.h>
AnalogOutputFirmata analogOutput;

FHEM configuration

Requirements

1. A working FHEM installation in version 5.5 or higher
2. Directory FHEM from this project

Setup

1. Copy the project directory FHEM into the root directory of your FHEM installation.
2. Add a device for Firmata
3. To send, add a device for the sender
4. To receive, add a device for the receiver

Example

Now let's say you want to switch an Intertechno socket outlet.

• Your Arduino is connected to /dev/ttyUSB0,
• RF sender module is connected to pin 11,
• RF receiver module is connected to pin 2

RCSwitch Configuration

define firmata FRM /dev/ttyUSB0@57600
define rc_sender FRM_RCOUT 11
attr   rc_sender IODev firmata
define rc_receiver FRM_RCIN 2
attr   rc_receiver IODev firmata
define switch IT 0FF00F0F0F 0F 00
attr   switch IODev rc_sender

To switch your socket, call set switch on. To send a tristate code directly without IT device, call set sender tristateCode 0FF00F0F0F0F. When you press a button on the remote of your socket, the device rc_receiver receives a message and the state of the IT device changes.

Known problems

Signal quality

The signal quality depends on the quality of the RF modules and the antenna.

• Each RF module should have an antenna with a length of λ = c₀/f (speed of light divided by frequency) or a fraction of it. An effective and cheap antenna is a copper wire with the length of λ/4, e.g. 17.4 cm for 433 MHz.
• Even very cheap senders (XY-FST, FS1000A) have shown good results.
• For best results, a superheterodyne receiver (RXB6) is recommended. Very cheap receivers (XY-MK-5V) may work, but this depends on the environment and the sensitivity of controlled devices.

Build environment

RCSwitchFirmata was developed on and works with Arduino IDE 1.5.6-r2. It seems that in later versions of the IDE, the include mechanism was changed, causing compile errors. This problem occurs at least on version 1.5.8 & 1.6.4.

Project status

This project was developed on the FHEM forum in 2014 and moved to GitHub in 2015.

History

See the thread FHEM+Arduino Firmata via Ethernet+RF 433 Mhz Sender+Baumarkt-Funksteckdosen for details about the development of this project.

Links

• FHEM+Arduino Firmata via Ethernet+RF 433 Mhz Sender+Baumarkt-Funksteckdosen
• Arduino Firmata in FHEM
• Firmata
• rc-switch on Google Code
• rc-switch on GitHub