Page 182 - Making PIC Microcontroller Instruments and Controllers

TO THE EIGHI PNOJECTS
175 AI{ II{IFODUCTIOI{

offers you. thc experimenter.
PIC micrcprocessors They sclectively demonstrate what
can be donc by the anateur expedmenter and engineeing student with fai y mjnjmal
resources. This is an introductory lulorial, as opposed to a highly lechnical trealment
you mighi find in a morc rigorors iext. The projccts are fairly straightforward and are
designcd to expand your hodzons and give you the confidence you need to create and
buildthc instruments neoessary for the work you wanlto undertake. They demonstrate
avaried approach to a seemingly random setofproblems, which when seen as a whole,
we need to movc to the next level, which is ofcourse the design
give us ihe expericnces
and construction ofthe instruments requircd.
The eight instru cnts are:

lnstrument Name Function Reing Sfudied
l. Tachometer Courting pulscs (synchronous)
2. Mctronome Timer tecllniqucs
3. Ma$le counter Couniing techniques (asynchfonous)
4. Dual lempcrature sensor Analog{o-digital conversion considenlions
5. Aftilicial horizon rable Converting pulses to Inotion
6. Touch screen A uscful real-world scanning application
7. Single-poinlcontrollef Controlling a "set point" process with details
8. Solar collector Dala logging over time

Thesc cight projects reFescnt the eight fundamental lechniques you mlrst mastef to
be able to build the instruments and controllers you need. Each instrumenl in the series
and address onc part of lhe datacollection or conversion problem-
is designed !o jsolate
Once we undcrstand the basic componcnts in these systems, wc can proce€d with thc tech-
niques necessary to design the Plc-based inslruments Decessary ior the tasks it hand.
As alwals. the lirstthingwe musl do is to convert lhe signal wc areinterested ininto
a uscable digital format. Oflen. you may need !o amplify the signal bcibre converling
it to lhe digital format requircd.

l. The lachometer project is a basic exercise in understanding
lhe oounling ofpulses
thar can come in at widely varying rates. (It also teaches you how to use scven seg-
ment displays.)
2. The mefonomes have to do withlearning how to usethe timers to create accumtely
timed intervals. Thc metronomes we create will opefate idenlically, but will use the
various timers to creale thc intervals needed. This is adetailed exercisc in the use of
limcrs in the PIC 16F877A. Both the LAB-XI and the tachometer crcaled earlier
wilycan be used to create thc metronomes.
3.In the marble counters sertion. we will leam aboul good. bad, and ambigltous sig-
nals, and experiment wilh some ofthe techriques uscd for sofiirg things out with a
micrcprocessor as we collecl the data. These counling techniques can and will be
applied 10 all sorts of instrumenls that yo create in the future.
4. The two thcnnometer instrument allows you lo measure lwo q antities simultane_
but they do not have to be. Onc can also be designcd
ously. Both are tcmperaturcs,
and the instruments you crealc
to be a set point. This is the basic instrument/controllet
will csscntially be varialions ofthis project, wilh lhc appropriate signal conversion