Microcontroller-Based Weather Station
The first will be our outdoor
network. This network will run
to our weather pole where all
our outside sensors are
located. The second network
will run to a Hobby Boards
barometer module which will
form our indoor network.
Schematic 2 shows the
connections of the two networks. Note that I added R3, a
100 ohm resistor in series with
my outdoor network. I have
200-300’ Cat3 cable run which
is the worst case scenario and
the resistor helps to reduce
errors. I actually placed the
resistor inside the modular box
so it could be removed when I
upgraded the cable to Cat5.
I am also using I/O port 15
to supply 5V to the pullup resistor R1. You could have tied the
resistor to VDD, but this makes
it easier to connect the resistor
to the removable header.
Let’s start by adding a
connection to a modular jack
so that you can easily connect
your outdoor sensors to the
weather station.
■ SCHEMATIC 2
STEP 1: Take a snapable female
header and cut off a three-pin section
and place it on the WorkBoard
header labeled VSS, VDD, and
P13. Solder a 1K resistor between the
VDD and P13 leads, as shown in
Figure 10.
STEP 4: The connection to the indoor
network is similar to the outdoor
network. Start by cutting off a
two-pin section from a female header
and slip it over ports 14 and 15.
Solder a 1K resistor between the
two leads on this header then attach
a 4” yellow wire to the lead
connected to port 14, as shown in
Figure 13.
STEP 5: Snap off a two-pin section
STEP 2: Attach a 4” piece of black
telephone wire to the lead labeled
VSS, then attach a yellow wire to
the lead marked P13, as shown in
Figure 11.
STEP 3: Attach a modular jack to the
base you are using for the project.
Most modular jacks come with foam
tape for this. I used small #4 machine
screws to mount mine.
Attach the black wire (connected
to VSS) to the green wire on the
connector. Attach the yellow wire
(connected to P13) to the red wire on
the connector, as shown in Figure 12.
■ FIGURE 10
■ FIGURE 11
■ FIGURE 12
June 2007 33
