BY MICHAEL SIMPSON
It’s the results of this experiment that I
am basing this project.
ports 7 and 13. Install a
two-pin header into the
two pads marked – and +
near the upper right hand
of the board shown in
Figure 6. Install a five-pin
female header into the
pads marked –, +, Rx, Tx,
and Atn in the lower left
hand corner of the
board. This header will
be used to insert an
EZRS232 for programming the DiosPro. Install
a 100K resistor between
I/O port 7 and Vss as
shown in Figure 7.
■ FIGURE 1
Building Sensor Pads
It’s time to create a couple of sensor pads that you can use for your own
experiments and eventually use on
your own doggy dish project. You will
need some foil tape — the kind that
you can purchase from the heating and
air-conditioning section of your home
center. One side is conductive and the
other has a very strong adhesive. Take
an 8” piece of foil tape and split it
down the middle as shown in Figure 1.
Next, take a 12” piece of solid
hookup wire and strip about 4” from
the end. Lay the wire on one of the tape
strips foil side up as shown in Figure 2.
Take the other tape strip and remove
the adhesive backing and place it over
the wire and original strip as shown in
Figure 3. Use your thumb to smooth
out the bubbles and to make sure the
wire is firmly sandwiched between the
two strips. You now have a sensor
pad. You will need two of these sensor
pads. For now, attach the two sensor
pads to a jar similar to the one shown
in Figure 4. Use cellophane tape so
they can be removed later.
■ FIGURE 2
■ FIGURE 3
• STEP 2 — Attach the DB- 9
Connector. Break off a two-pin header
from one of the headers that came
with the Dios Carrier 1 and solder it to
the pins 4 and 5 as shown in Figure
8A. Then break off a single pin and solder it to pin 7 as shown in Figure 8B.
Attach the DB- 9 connector to the
Dios Carrier 1 as shown in Figure 9.
The header pins 4 and 5 are soldered
on the top of the board to I/O ports 2
and 3. The header pin 7 is soldered on
the bottom of the board to I/O port 0.
This connector will eventually connect
to the FireCracker.
shown in Figure 10. To do this, you need
to pry up the small tab covering the pin.
Keeping the orientation of the receptacle the same, push it into the slot next to
the black wire. It should snap into place.
Snap off a single one-pin section
from the 36-pin female header and
solder the end of the wire connected
to the sensor pad to this female
header. For more strength, slip a piece
of 1/8” heat shrink over the pin and
shrink as shown in Figure 11.
Controller Board
Construction
• STEP 4 — Sensor Pad Test. If you
have not done so, you need to
assemble and test the EZRS232 board
• STEP 3 — Final Prep. Move the red
wire on the battery connecter so that it
is located next to the back wire as
■ FIGURE 4
Before we can proceed with the first
test, we need to build the controller
board that will take readings and send
out our X10 control codes. We will use
a DiosPro 28-pin chip, a Dios Carrier1
board, and a FireCracker X17A. I will
provide a complete list of materials at
the end of this article along with
sources for the various components.
■ FIGURE 5
• STEP 1 — Build the Dios Carrier
Board. Use the instructions that
come with the Dios Carrier 1 board
to assemble it. Don’t assemble
the two 12-pin headers. When
complete, it should look like
Figure 5. Install one-
pin headers into ■ FIGURE 6
May 2007 37
