Page 153 - Making PIC Microcontroller Instruments and Controllers

THE HAFDWARE 't45

1 Logic ground
2 Logic power 5 volts
3 Contmst of the display, can usually be grounded.
Fegisterselect )These are
5 Read,ll/fiie )lhe 3 control
6 Enabe ) lines
7
8
I
1 0
1 1 )8 nes )hall ofthe pon
'12
) ot daia ) can also
1 3 ) ) be used
) )see PBP manual
Backlight power )These hvo lines can
Backlight ground )usually be ignored

only one PIC in this book. in our case this means we will use the 16F877A. I h.tve
included the circritry and code tbr this in the Progfam 9.1 and F-igure 9.1 so you caD
scc cxacdv what nccds to bc donc.
To keep ir simple. lel's use PORTA and PORTB. because lhesc ports arc available
on cven thc slnailcr MCLIS. and if we use a dedicared MCU ro control our l-CD. i! will
in all prcbabiiity be a smallernore inexpensive l8'or20-pinMCU. Let's use thclincs

Lincs | 1o 3 of PORTA as lhc conlrol lincs and
Lhes 0 to 7 ofPORTB ris the data lines

\ re can redefine these to be more rational addresses whenever $,e want. and none of
the pfogramming will have to change. Just DEFINE what pofts and lines you want to
use atthe top ofthe progmm. and the aliases assigned to their will identify then as needed.
with this in mind. let's create the sotiwarc to conlol a 2 line by-16 charactef dis-
plalr. Oncc wc arc happy wilh lvhat wc havc crealed. wc can migralc lhc codc 1() other