shown in Figure 14. For the receiving
end of the link, I used the same setup
that we used earlier to test the
completed Rex board. The
transmitting software for Tex
( TexOut.bas) and the receiving
software for Rex ( RexIn.bas) is
available on the N&V website. The
programs are both very basic.
Essentially, Tex repetitively checks
input3 and transmits two different
infrain2 codes: “0” = “no motion”
and “1” = motion. Rex receives each
transmission and relays an
appropriate message to the terminal
window. Download both programs,
install each one on the corresponding
board, and test your system.
Because Tex is battery powered,
it’s a good idea to reduce power
consumption as much as possible.
There are three aspects of Tex’s
software that are helpful in this regard.
First, the 08M has a feature called
brownout detection (BOD) which
cleanly resets the processor in the
event of a power brownout (i.e., a
temporary drop in the input voltage).
It’s a great feature for line-powered
circuits but not really necessary with
battery-based systems, and it does
require a fair amount of power to
operate. Fortunately, the 08M
supports software commands to
enable or disable BOD (enablebod
and disablebod), so the inclusion of
the disablebod statement in Tex’s
software reduces the power
consumption of the circuit.