DOING BIG THINGS
WITH LITTLE MICROS
by Fred Eady
All things complex are based on things most basic. So, if you
wish to perform high-level tasks with a PIC microcontroller, you
must first master the low-level tasks. This month, we’re going
to move away from the mechanics of robotic arts and focus on
basic electronic principles that can be amplified to form the
soul of a subservient mechatronic being.
The intent of our upcoming discussion is to show you
how to perform higher level tasks by combining multiple
low-level tasks. By the time your eyes cross the last period
of the last sentence of the last paragraph of this article,
you’ll have been exposed to a number of PIC
microcontroller variants performing basic tasks working
together to accomplish a higher goal. The largest PIC
microcontroller we will fill with code is the
20-pin PIC16F690.
A 10-pin PIC10F2068 will be the smallest task contributor.
Let’s begin by examining the hardware support platform.
PICDEM Lab Development Board
As you can see in Photo 1, I’ve already wired in an
Optrex 4x20 LCD into the fabric of my PICDEM Lab
development board. It’s rather obvious from the photo
that this board is designed to be a PIC aircraft carrier
with each of three PIC variants supported by its own
ICSP interface and a common adjustable regulated
power supply.
Two quads of P-channel and N-channel MOSFETs
are included in the PICDEM board package to support
the brushed DC motor and the on-board speaker. A
CD-ROM is included that contains canned HI-TECH
C-based projects whose hardware can be assembled
using the electronic parts kit that is also part of the
development board package. In addition to the
PIC16F690, PIC16F88, and PIC10F206 mounted on
the out-of-the-box PICDEM board, a PIC16F616 and
PIC12F615 can be found in the parts kit, as well.
A PICkit 2 is issued as standard equipment with
the PICDEM to provide a simple and easy to use
programming/debugging interface.
The idea behind this board design is to take a
novice PIC user through the ins and outs of driving
LEDs, capturing switch closures, and using timers.
From a magazine reader’s point of view, it’s much
easier to read a binary pattern from a backlit LCD
than from a row of LEDs. Another advantage
gained by using an LCD is that alphanumeric
information resulting from a project’s operation
can be easily conveyed to the reader. That is the reasoning
PHOTO 1. This is a standard PICDEM lab development board
with an Optrex 4x20 LCD electrically attached to its PIC16F88.
Although the board is intended to educate PIC novices, old hat
PIC users can also benefit from its circuitry. The message on the
LCD says it all.
40 SERVO 08.2009
