Page 22 - Making PIC Microcontroller Instruments and Controllers

Asmall breadboard space is provided on rhe LAB Xl itselfto allow the addition of
a limited number of hardware iterns you may need to experiment with.
See the support Web site regarding the availability of readynade headers and cables
and so on, for use wirh the LAB-X l. (These are the devices I needed and made up to
allow me to experiment with rhe l6F877A when rhe circuitr v I required was not avail_
able on the LAB-X l.)

Special Precautions and Notes

of Interest

These caveats could have been placed later in this book but a(e included here ro encour
age you to think about the programmer besr suited to your needs.
Pin 87 on the 16F877A is connected ro a programming pin on rhe EPIC parailcl plo_
grammer at all times, and the programmer forces this pin high. ff you are using this pin in
your exp€riment and you decide it must be ,rlr, you must disconnect the EPIC program_
mer to release this pin. If you are using a serial or USB programmer, it can be lelt coDnected
to the LAB-XI at all times. The major bcnefit of usjng the USB or p,rallel programmer js
that it frees up your computer's serial pot for cornrnunications to the LAB Xl.
to
Resistor R17, which is connected to the keypad, is ofno consequence rhe opera_
tion of the LAB-XI. Ii is needed fbr some (pIC) pro$amming functions and can be
ignored (fbr ou. purposes).

Data Sheets

The hardest pall ofleaming how to use these microcont ollen is understandirg the huee
dararheet\.
Srnce eirch ddlarheet ,5 similaf bul dj Ffer.nr r'om.,.n o,ne, drruit ect. ,i,
lead\r(edlo'ele.Ioneurr\ornicfoconlroller.togcltlniliir;ilhundlhenusel;em
for all your inirial projecrs. ln this workbook, the two discussed/mentioned are the pIC
l6F84A (|his chip will nor fit in the 40 pin socker provided bur is a good alternare
choice lbr the cost conscious), for yow small proj ects, and the pIC l6Fg77A. for larser
more (omprehen\i!e
projecl\. tach of lhece uses fld.h metnuD and ctn therctorc be
proglammed over and over again with your plogrammer and a prograrrming socket. The
pocessor you select will be detemfued by the kind ol VO and intemal features you need,
and the availability of inexpensive OTp (one time programmable) equivaients ifyou
plan to go into producrion.
is
A lot of the iniomation in the datasheets morc complicated and detailed than we
need Lo worry about at rhis lime, and we can do a lor of uselul work without under
js
standing it in every detail. Our main interesr in what the various resisters are used
for and how lo u.e rhem prcperl) .rnd effectivel) The limin! dirgram:rnd other darc
atnut the jnterl workings ofthe chips are beyond what we need to undentand at the level
of this resource book. Our inrerest is in being abte ro set rhe vl]rious .egisters in the svstem