sx52 timers

Vertex78 · 2006-10-27 20:05

I am trying to learn how to use the timers on the sx52. I have read a bit on the subject but I am still confused on how exactly you would set everything up in asm to do anything. Could someone either post some simple code to create a pwm signal with a 50% duty cycle using the timers, or reference me to a good link that explains how to work with the timers.

Thanks

Vertex78 · 2006-10-27 21:20

ok, here is what i got so far. I think it might work right, but I haven't gotten the chance to actually try it and hook up the scope.
I am assuming he output pin will be rb.6 for timer1, is this correct?

device sx52
IRC_CAL IRC_SLOW
RESET initialize
FREQ 75_000_000
 

;**********
; EQUATES
;**********
;timer1
rT1CPL            EQU        $00
rT1CPH            EQU        $01
rT1R2CML        EQU        $02
rT1R2CMH        EQU        $03
rT1R1CML        EQU        $04
rT1R1CMH        EQU        $05
rT1CNTB            EQU        $06
rT1CNTA            EQU        $07
wT1R2CML        EQU        $12
wT1R2CMH        EQU        $13
wT1R1CML        EQU        $14
wT1R1CMH        EQU        $15
wT1CNTB            EQU        $16
wT1CNTA            EQU        $17

;timer2
rT2CPL            EQU        $00
rT2CPH            EQU        $01
rT2R2CML        EQU        $02
rT2R2CMH        EQU        $03
rT2R1CML        EQU        $04
rT2R1CMH        EQU        $05
rT2CNTB            EQU        $06
rT2CNTA            EQU        $07
wT2R2CML        EQU        $12
wT2R2CMH        EQU        $13
wT2R1CML        EQU        $14
wT2R1CMH        EQU        $15
wT2CNTB            EQU        $16
wT2CNTA            EQU        $17


initialize

    ;load t1 compare register1 with the value of 50
    mov w,#wT1R1CML
    mov m,w
    mov w, #50
    mov !rb,w
    mov w,#wT1R1CMH
    mov m,w
    mov w,#0
    mov !rb,w

    ;load t1 compare register2 with the value of 50
    mov w,#wT1R2CML
    mov m,w
    mov w, #50
    mov !rb,w
    mov w,#wT1R2CMH
    mov m,w
    mov w,#0
    mov !rb,w

    ;do i need to change any of these?    
    mov w,#wT1CNTA
    mov m,w 
    mov w,#%11000000

    ;setup for prescale of 1/128 and pwm mode
    mov w,#wT1CNTB
    mov m,w
    mov w,#%00011101

main
    
jmp main

Bean · 2006-10-27 23:05

In SX/B you can just do:

OUTPUT RB.6         ' Timer1 PWM output pin
TIMER1 PRESCALE, 7  ' 1/128 prescale
TIMER1 PWM, 50, 100 ' Set PWM mode output is on pin RB.6

OUTPUT RB.6 ' Timer1 PWM output pin
TIMER1 PRESCALE, 7 ' 1/128 prescale
TIMER1 PWM, 50, 100 ' Set PWM mode output is on pin RB.6

Then look at the generated code.

Bean.

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sx52 timers

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