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2–83
Motorola Sensor Device Data
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DONE JMP DONE ; End
SILENCE BRSET 7,PORTB,SILENCE ; Sample switch S2 for stopping LED
SEI
BCLR 3,PORTB ; Turn off LED
JMP DONE ; End
******************************************
* *
* Timer service interrupt *
* Alternates the PLMA data *
* and bit 3 of Port B *
* *
******************************************
TIMERCMP BSR COMPRGT ; Branch to subroutine compare register
BRSET 1,PORTB,SKIPBUZZER ; Branch if J1 is OFF
LDA PLMA
EOR #$80 ; Alternate the buzzer
STA PLMA
RTI
SKIPBUZZER BRSET 3,PORTB,OFF_LED ; Alternate LED supply
BSET 3,PORTB
RTI
OFF_LED BCLR 3,PORTB
RTI
******************************************
* *
* Subroutine reset *
* the timer compare register *
* *
******************************************
COMPRGT LDA TCNTHI ; Read Timer count register
STA TEMPTCNTHI ; and store it in the RAM
LDA TCNTLO
STA TEMPTCNTLO
ADD #$50 ; Add C350 H = 50,000 periods
STA TEMPTCNTLO ; with the current timer count
LDA TEMPTCNTHI ; 1 period = 2 us
ADC #$C3
STA TEMPTCNTHI ; Save the next count to the register
STA OCMPHI1
LDA TSTATUS ; Clear the output compare flag
LDA TEMPTCNTLO ; by access the timer status register
STA OCMPLO1 ; and then access the output compare register
RTS
******************************************
* *
* Delay Subroutine for 0.20 sec *
* *
* Input: None *
* Output: None *
* *
******************************************
DLY20 STA STACK+2
STX STACK+3
LDA #!40 ; 1 unit = 0.7725 mS
OUTLP CLRX
INNRLP DECX
BNE INNRLP
DECA
BNE OUTLP
LDX STACK+3
LDA STACK+2
RTS
******************************************
* *
* This subroutine provides services *
* for those unintended interrupts *
* *
******************************************
SWI RTI ; Software interrupt return
IRQ RTI ; Hardware interrupt
TIMERCAP RTI ; Timer input capture
TIMERROV RTI ; Timer overflow interrupt
SCI RTI ; Serial communication Interface Interrupt
ORG $3FF2 ; For 68HC05B16, the vector location
FDB SCI ; starts at 3FF2
FDB TIMERROV ; For 68HC05B5, the address starts at 1FF2
FDB TIMERCMP
FDB TIMERCAP
FDB IRQ
FDB SWI
FDB RESET
F
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