Page 230 - Making PIC Microcontroller Instruments and Controllers

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Metronome usinsTimerl (Continuect)
liafiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiia!1i11!i9l:
; set the port directions. ire nust set all of PoRTD and all of
; PORTE as outputs
; even lhorlgh PORTE has only 3 1ines. The other 5 lines will
; be ignored by the systen.

TRISC = %11111001 ; set PORTC.2, the speaker
; connection
; to an output line
tRtSD - %00000000 ; set all PORTD lines to output
TRrsE = %00000000 ; set att poRTE lines Lo oubput
PORIE.2=o ; set LCD to write node
x vAR woRD ; set up the variable
'
A ! c o N 1 = % 0 0 0 0 0 1 1 1 \ ^ M " _ o q - r o - D q : r a t - o n r o
: . - g r , . e _
, needed for the 15F877A see noles
PAUSE 500 ; pause for LCD !o sta.t up
LDOUT $FE/ L ; clear sc.een
ON IMIERRUPT GOTO INt ROUEIIqE j -- ) p-ogrqn /hor- .o So ol
, interxupt
llcoN=%01110001 '- .e L rp en-D_e
PIE1.0=1 ; clears the interrupr flag so it can

INTCOIi.6=1
OPTION-REG=%000001LL ; sels the prescalar ro 256
x=0 ; seLs the iniliat value for X
_ o o D
M A I N ! : r h o a d i l o / . e p o g _ d n
.'Metrono@"
LCDOI'I $FE, $80. ; dispray frrst line
LCDOu! SlE, $C0, DEC5 x ; vrite X to 1lne 2
IF X=15 TBEN ; check value of X
x-0
TOGGI,E PORTC.2 ; o9q16 h6 -pe- <e so
; i !
EIIDIF
GOIO MAIN ; repeaL Loop

r o n o r a . o T p 4 .
INr-ROIXIINE ! ; interxupt service rouiine
X=*+X ; increment the counter
PlR1.0=0 _nr e!! .pL nag
RESUME ; qro back to where you were
E N A a L E i r 6 o d s - l c t ' ) 1 L o . n - o m p : i e .

END , afl prograns nust end with End