User Guide
Pi Rf-Transmitter Board
Introduction
The RF transmitter add-on board can be used
with the R-PI to control simple Energenie radio
controlled sockets using a small software
program. We have written a simple program in
Python to allow us to switch the sockets on and
o with a single keyboard press.
The add-on board connects to the row of pins
called the GPIO which can be controlled as
either input or output lines under your
software control.
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How it is controlled by Software
The pin header connects to the add-on board
as follows to allow you to control the GPIO lines
as outputs to drive the radio frequency
transmitter.
Your software will use the outputs on the GPIO
connector to drive the add-on board. We will
write some code in Python to switch the two
Energenie sockets on and o .
There are two parts to the transmitter board.
The encoder and the modulator:
1) The encoder will accept 4 input signal levels
programmed onto 4 of the GPIO lines (D0-D3)
as shown above. It will then serialise them on a
single line to the modulator part.
2) The modulator transmits the serialised
signal. It needs to be programmed in Ampli-
tude-Shift Keying (ASK) mode for the sockets
using a GPIO signal. It also needs to be enabled
by a separate GPIO signal.
Fig. 1: R-Pi with piggy back RF-transmitter board
Installing the board
Install the board on to the row of pins as show
in the picture and connect your Raspberry-Pi as
normal to a monitor, mouse, keyboard and USB
power supply.
Here are the pairs of codes using D0-D3 that
can be sent to control sockets; we will use
socket 1 and socket 2 in the sample program at
the end:
Firstly, we need to install a Python module,
RPi.GPIO, to enable software control of the
GPIO pins for the Raspberry Pi. Open an
LXterminal from the desktop and type the
following lines:
sudo apt-get install python-rpi.gpio
The socket must then be programmed to learn
a control code from the transmitter. To do this
the socket must be in learning mode indicated
by the lamp on the front of the socket housing
ashing slowly. If it is not doing this, press and
hold the green button on the from of the
housing (while the lamp is o ), for 5 seconds or
more and then release it when the lamp starts
to ash at 1 second intervals. Then send a signal
to it from you program by hitting the return
key. Acceptance will be indicated by a brief
quick ashing of the lamp on the housing
which will then extinguish. Program rst one
socket then the other in this way, otherwise
they will react to the same signal.
You can then toggle the sockets on and o by
hitting the return key. You can also switch them
manually on and o by brie y pressing the
button on the front housing.
You can always reset the socket programming
by holding down the green button for 5
seconds or more as mentioned before.
To increase the range of the transmitter you
may wish to add an extra antenna to the circuit
board. You can do this by soldering a piece of
ordinary copper wire 13.5cm long into the hole
marked ANT1 on the circuit board.
IMPORTANT:
The sockets will need to be inserted
into separate mains wall sockets with a physical
separation of at least 2 metres to ensure they
don't interfere with each other. Do not put into a
single extension lead.
Now, open a text editor such as leafpad and
type the python code listed at the end called
ENER002- 2PI.py into a new le under home/pi
(or, more easily, download it from the
energenie4u.co.uk website and copy using a
USB ash drive). This program will allow us to
send coded commands to the sockets to
program them and then switch them on and
o when the return key on the keyboard is hit.
Controlling the sockets
Launch your program by typing the following
command at the prompt in the LXterminal
window:
sudo python terminal ENER002-2PI.py
Then insert one of the radio controlled sockets
into a mains wall socket which is switched on.
Energenie is a trading name of Sandal plc,
Claremont House, Deans Court, Bicester, UK, OX26 6BW
If you have questions, please visit us at
www.energenie4u.co.uk
DIY/Open Source Hardware
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