Samsung S3F80JB - Manual (Page 254)

S3F80JB BASIC TIMER and TIMER 0
10-11
PROGRAMMING TIP — Programming Timer 0
This sample program sets timer 0 to interval timer mode, sets the frequency of the oscillator clock, and
determines the execution sequence which follows a timer 0 interrupt. The program parameters are as follows:
— Timer 0 is used in interval mode; the timer interval is set to 4 milliseconds
— Oscillation frequency is 6 MHz
— General register 60H (page 0)
→ 60H + 61H + 62H + 63H + 64H (page 0) is executed after a timer 0 interrupt
VECTOR 00FAH,T0OVER ; Timer 0 overflow interrupt
VECTOR 00FCH ,T0INT ; Timer 0 match/capture interrupt
ORG 0100H
RESET: DI ; Disable all interrupts
LD BTCON,#0AAH ; Disable the watchdog timer
LD CLKCON,#18H ; Select non-divided clock
CLR SYM ; Disable global and fast interrupts
CLR SPL ; Stack pointer low byte
→ "0"
; Stack area starts at 0FFH
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LD T0CON,#4BH ; Write ‘00100101B’
; Input clock is f
OSC
/256
; Interval timer mode
; Enable the timer 0 interrupt
; Disable the timer 0 overflow interrupt
LD T0DATA,#5DH ; Set timer interval to 4 milliseconds
; (6 MHz/256)
÷ (93 + 1) = 0.25 kHz (4 ms)
SRP #0C0H ; Set register pointer
→ 0C0H
EI ; Enable interrupts
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T0INT: PUSH RP0 ; Save RP0 to stack
SRP0 #60H ; RP0
← 60H
INC R0 ; R0
← R0 + 1
ADD R2,R0 ; R2
← R2 + R0
ADC R3,R2 ; R3
← R3 + R2 + Carry
ADC R4,R0 ; R4
← R4 + R0 + Carry
(Continued on next page)