195 lines
3.9 KiB
NASM
195 lines
3.9 KiB
NASM
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; ***************************************************************************
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; defs
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.equ TIMER_FLAGS_100MS = 1
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.equ TIMER_FLAGS_1S = 2
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; ***************************************************************************
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; data
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.dseg
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timerModuleData:
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timerModuleTickCounter: .byte 1 ; only low byte used
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timerModuleFlags: .byte 1
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timerModuleCounterSecs: .byte 4
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timerModuleData_end:
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; ***************************************************************************
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; code
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.cseg
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; ***************************************************************************
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; Timer_Init
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;
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; IN:
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; - nothing
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; OUT:
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; - nothing
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; USED: r16, r17, x
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Timer_Init: ; setup timer for 15.2588 interrupts per second (e.g. every 65.5 ms)
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; reset data in SDRAM
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ldi xh, HIGH(timerModuleData)
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ldi xl, LOW(timerModuleData)
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ldi r16, 0
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ldi r17, (timerModuleData_end-timerModuleData)
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rcall Utils_FillSram
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; CTC mode (WGM2:0=2, OCR0A=value, OCF0A Flag =1, -> IRQ_OC0A
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; CMP-A interrupt about every 100ms
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ldi r16, (1<<CS02) | (1<<CS00) ; Prescaler 1024
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out TCCR0B, r16
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ldi r16, (1<<WGM01) ; CTC mode
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out TCCR0A, r16
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ldi r16, 98-1 ; (1,000,000/1024)/10 = 97.65625
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out OCR0A, r16
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ldi r16, (1<<OCF0A) ; clear pending interrupts
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out TIFR0, r16
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ldi r16, (1<<OCIE0A)
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out TIMSK0, r16
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ret
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; ***************************************************************************
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; Timer_Fini
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;
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; IN:
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; - nothing
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; OUT:
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; - nothing
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; USED:
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Timer_Fini:
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ret
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; ***************************************************************************
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; Timer_Run
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;
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; IN:
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; - nothing
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; OUT:
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; - CFLAG: set if something done, reset otherwise
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; USED: r15, r16, r17 (more depending on called routines)
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Timer_Run:
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in r15, SREG
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cli
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clr r16
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lds r17, timerModuleFlags
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sts timerModuleFlags, r16
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out SREG, r15 ; restore global IRQ flag
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mov r16, r17
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andi r16, TIMER_FLAGS_100MS
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breq Timer_Run_l1
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push r17
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rcall onEvery100ms
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pop r17
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Timer_Run_l1:
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mov r16, r17
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andi r16, TIMER_FLAGS_1S
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breq Timer_Run_l2
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push r17
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rcall onEverySecond
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pop r17
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Timer_Run_l2:
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sec
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tst r17
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brne Timer_Run_end
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clc
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Timer_Run_end:
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ret
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; ***************************************************************************
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; OC0A interrupt handler
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;
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; Called every 100 milliseconds, sets flag TIMER_FLAGS_100MS.
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; Increments an internal counter. If that counter reaches 10 the seconds counter is incremented and a the flag
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; TIMER_FLAGS_1S is set.
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timerIrqOC0A:
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push r15
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in r15, SREG
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push r16
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push r17
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lds r17, timerModuleFlags
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ori r17, TIMER_FLAGS_100MS
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lds r16, timerModuleTickCounter
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inc r16
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cpi r16, 10
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brcc timerIrq2_l1
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sts timerModuleTickCounter, r16
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rjmp timerIrq2_l2
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timerIrq2_l1: ; increment seconds
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; reset 100ms counter
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clr r16
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sts timerModuleTickCounter, r16
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; increment seconds
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push xh
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push xl
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push r18
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push r19
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push r20
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push r21
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push r22
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ldi xh, HIGH(timerModuleCounterSecs)
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ldi xl, LOW(timerModuleCounterSecs)
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ld r18, x+
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ld r19, x+
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ld r20, x+
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ld r21, x
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clr r22
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inc r18
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adc r19, r22
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adc r20, r22
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adc r21, r22
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st x, r21
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st -x, r20
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st -x, r19
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st -x, r18
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pop r22
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pop r21
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pop r20
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pop r19
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pop r18
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pop xl
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pop xh
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ori r17, TIMER_FLAGS_1S
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timerIrq2_l2:
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sts timerModuleFlags, r17 ; store new timer flags
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pop r17
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pop r16
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out SREG, r15
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pop r15
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reti
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