Question

有人能发现为什么这段代码无法输出恒定脉冲？至少我的Fluke无法触发高脉冲，看起来它来得有点随机..

这是我的第一个asm程序，所以请记住它可能是代码中的天真错误

;INITIAL
.include "tn10def.inc"      ; Include file for Attiny10
.org $0000
     rjmp RESET             ; ISR reset vector (also start of prog)
.org $0008
     rjmp WDT               ; Watchdog reset vector 


.def t          = r16       ; temp register
.def PWM_c1     = r24       ; PWM counter register 1
.def PWM_c2     = r25       ; PWM counter register 2
.def PWM_c3     = r17       ; PWM counter register 3

RESET:
;INIT_STACK:
    ldi t, low(RAMEND)      ; init high and low bytes for stack pointer
    out spl, t
    ldi t, high(RAMEND)
    out sph, t
;INIT_SLEEP:
    ldi t, (0<<SM2)|(1<<SM1)|(0<<SM0)|(1<<SE)
    out SMCR, t             ; set power down mode at sleep command
;INIT_ISR
    sei                 ; enable global interrupts
;INIT_POWERSAVER
    ldi t, (1<<ADC1D)|(1<<ADC0D)
    out DIDR0, t            
;INIT_CLOCK
    ldi t, 0xD8             ; write signature
    out CCP, t
    ldi t, (1<<CLKPS3)|(0<<CLKPS2)|(0<<CLKPS1)|(0<<CLKPS0) 
    out CLKPSR, t           ; prescale by 256

MAIN_LOOP:
    rcall PWM_INIT
    rcall POWER_DOWN        ; WDT power down    
    rjmp MAIN_LOOP

PWM_INIT:
    ldi PWM_c3, 255         ; total number of pulses
PWM_START:
    sbi PORTB, led          ; set out high
    ldi PWM_c1, 0
    ldi PWM_c2, 0
PWM_LOOP:
    inc PWM_c1
    cpi PWM_c1, 16          ; target count (PWM high)
    breq PWM_OUT_LOW
    cpi PWM_c1, 208
    brne PWM_LOOP           ; first loop counts to 208
    inc PWM_c2
    cpi PWM_c2, 5
    brne PWM_LOOP           ; second loop counts to 5
    dec PWM_c3
    brne PWM_START          ; counts down number of pulses
    ret
PWM_OUT_LOW:
    cbi PORTB, led          
    rjmp PWM_LOOP

Answer 1

嗯，即使像这样的简单代码，处理器的运行也不是完全恒定的。您可能想要的是在芯片上使用定时器，并在溢出中断时更改信号。板载定时器非常一致。

AVR组装纯软件PWM不给出恒定频率

1 个答案: