for the Smart
designed into many other projects.
To review, Listing 1 is the
source code for the PICAXE-
28X1 and Listing 2 is for the
PICAXE-8M. Of course, you will
also need PICAXE programming
software to download the
firmware into the PICAXEs.
Happily, this software is available
as a free download from www.
picaxe.co.uk. In addition to the
free software, you can obtain an
enormous amount of easy-to-understand information on the
PICAXE from this website.
■ Air flow sensor assembly
for the Smart A/C Controller.
interface, connect pin 1 of J4 or J5 to pin 2 of a nine pin D
female socket; pin 2 of J4 or J5 to pin 3 of the nine pin D
female socket; and pin 4 of J4 or J5 (the ground pin) to pin 5
of the D female socket. If your computer only has a USB port,
you will need a USB-to-serial adapter. These adapters — which
usually come along with the necessary drivers on a CD-ROM
— are now quite inexpensive, easy-to-use, and can be
This controller can manage
the A/C’s compressor directly by
replacing the A/C’s thermostat
with a power relay, or it can be
used to turn on a small light
bulb located next to the A/C’s
thermostat. Installation details
are left to the reader. Keep in
mind that the two pin connector
J3 acts as an on and off switch
with a 1/2 ampere rating. It is the connector to use to
control either the compressor’s relay or a light bulb relay.
Even if you don’t plan on using this A/C controller in a
walk-in cooler, it is wise to still place the air flow sensor
board right next to the A/C’s evaporator coils so it can sense
the air flow. This is especially true in humid climates when
the thermostat setting is below 70 degrees. Make sure you
Order online at:
Development Tools for PIC® MCUs
microEngineering Labs, Inc.
Phone: (719) 520-5323
Fax: (719) 520-1867
Colorado Springs, CO 80960
With Accessories for $119.95: