PICAXE PRIMER
SHARPENING YOUR TOOLS OF CREATIVITY
■ BY RON HACKETT
EXPERIMENTING WITH THE
IR MULTI-BOARD
In the previous installment of the Primer, we constructed a stripboard version
of the IR Multi-Board, which can implement the full range of PICAXE IR
capabilities. We also tested it with a simple program that received and
decoded the signals from a Universal TV remote programmed to transmit the
Sony IR Control (SIRC) protocol.
This month, we’re going to continue
our exploration of PICAXE IR
capabilities, which we have divided
into three basic categories:
•The wireless transmission and/or
reception of standard serial data by
modulating and/or demodulating an
IR carrier wave.
•The transmission and/or reception
of IR signals that use the SIRC
protocol.
•Object detection using infrared
“echoes.”
IR TRANSMISSION
A SINRDC RSEIGCNEPATLISON OF
■ FIGURE 1. SIRC Tx-Rx setup.
At this point, we have already
successfully received SIRC IR
signals from a TV remote, so
let’s turn our attention to the
transmission of SIRC signals. In
order to do so, we will need to
use two IRMB systems — one
for transmission and the other
for reception. The experimental
setup that I used is shown in
Figure 1. As you can see, I’m
using two of my IRMB printed
circuit board (PCB) setups, but
any combination of breadboards, stripboards, and/or
PCBs will certainly work. You
can also see that the transmitting IRMB (on the right of
Figure 1) has been assembled
to mount horizontally on
the breadboard, while the
receiving IRMB (on the left)
has been assembled to mount
vertically. You can easily do the
same thing with the stripboard
■ FIGURE 2. Interior photo of
project box.
circuit we constructed last time. If
you are interested in doing so, see
the IRMB page on my website
( www.JRHackett.net/IRMB.htm).
If you want to do any sort of
range testing for your system, it will
be helpful to configure your transmitting unit as a battery-powered device.
The black project case below the
breadboard on the right of Figure 1
contains a nine-volt battery, a simple
+5V regulated supply, and an on-off
switch that controls power to the
breadboard (see Figure 2). The mess
in the lower left corner is the result of
my having to gouge out that part of
the case because the nine-volt battery was a little too large to fit inside
and I had already adhered the breadboard to the top of the box. (Plan
ahead, I always say!)
You can also accomplish the
same thing by simply attaching the
battery to the breadboard with a
rubber band and wiring the supply
components directly on the breadboard. However, if you would like to
construct a project case version of the
circuit, Figure 3 presents the circuit
schematic and Figure 4 presents the
stripboard layout I used. There is only
one cut needed on the bottom of the
circuit board (to separate the two
relevant switch contacts), but I
haven’t shown it because its exact
location will depend on the specific
switch you use. Also, you may need
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December 2008
