Page 145 - Making PIC Microcontroller Instruments and Controllers

136 SERIAL COiTMU ICAIION$ 60CKETS U9 A DUlo

RS232 Communications (Prograrn to receive and displav lnformalion
iiqfgtl..iiil&.Ol
lrcm the coripuier) (Cortlnued)
!o!l PoRfE.2 l,CD R/it rine Lot (l'i)
PAUSE 500 wait for LcD to srarlup
OPEION-REG.7 = 0 enable POR1B p!11lups

* E Y = 0 iniLialize vars
LASTKEY = 0

I,CDOUT gFE. 1 iniLialize and clear display

HSERIN 1. T!,A:BEI,' TC1IART ge! a char fron seriaL Port
I.CDOII! CIIAR send char !o disPLaY

'I.ABEIJ.
GOSUB CE'KEY ; get a ke\@ress if anv
IF (KEY != 0) AND (X:EY I= IJASTKEY) TSI:N
IISEROUT IKEY] ; send kev ou! seiiat porl
ETIDIF
LASfKEY - KSY ; save last key value
Gorlo LooP ; do it all over asain

GETKIY: ; subroutine Lo geL a kev fron ke)apad
K E Y = 0 , preset io no Kev
F O R C o L = 0 T O 3
; a1L oulput pins low
tRrsB = (DcD cor) ^ SFF ; se! one colmn Pin to oucput
Row = PoRtB >> 4
IF ROW l= %0000111,1 THEN GOTKEY ;
NEXT COIJ
BETITRN ; no key Pressed
GofKEY! ; change lod and col to asclr nunb
\0"
KEY = (coL * 4) + (NcD {Row ^ $F)) + ;
RETURN ; subroutine over
EAID ; end of Progran

Next, we combine the send and receive programs to give Lrs full communlcatlons
between the LAB-XI and the HyperTerminai program in the computer (This is left to
you. At this stage, you shoulal have no problen with implementing thisl howeve! a
couple of hints are Provided )
TL HyperTcrminal software lakes carc ofreceiving, displaying' and sending char-
acters. without need for any futher modification by us.
The LAB-XI software must receive characters from the terminal program and dls-
play them on the LCD. lt also has to read the keyboard and send what it sees to lhe
tcrminal. The receiving and sending m st be in the same main loop'