pwm.asm

用伟福6000写的PWM产生程序

;**************************************************************************
;                                超声清创机程序
;**************************************************************************
D200_R1          EQU     50H            ;延时寄存器
D200_R2          EQU     51H


        ORG     0000H
        GOTO    START

        ORG     0004H
        BCF     PIR1,TMR2IF
        RETFIE


        ORG     0055H

START:

;--------------------I/O口初始化--------------------

        BSF      STATUS,RP0
        MOVLW    00H
        MOVWF    TRISC
        MOVLW    01H
        MOVWF    TRISB

        BCF      STATUS,RP0
        MOVLW    00011000B
        MOVWF    PORTC
        MOVLW    11111101B
        MOVWF    PORTB


;---------------------产生PWM波---------------------

PWM:    BSF     STATUS,RP0               ;选BANK1
        MOVLW   40H                      ;36kHz
        MOVWF   PR2
        BSF     PIE1,TMR2IE
        BCF     STATUS,RP0               ;选BANK0
        BSF     INTCON,PEIE
        BSF     INTCON,GIE
        MOVLW   20H                      ;脉宽，高8位
        MOVWF   CCPR1L
        BCF     CCP1CON,4                ;脉宽，低2位
        BCF     CCP1CON,5
        MOVLW   00000000B                ;TMR2
        MOVWF   T2CON
        BSF     CCP1CON,2                ;CCP设置为PWM操作状态
        BSF     CCP1CON,3
        BSF     T2CON,TMR2ON


;------------------------main-----------------------

MAIN:   NOP
        GOTO    MAIN



;------------------------延时-----------------------
D200MS:      MOVLW   0EBH
             MOVWF   D200_R1              ;外层寄存器
D200MS_LP0:  MOVLW   0FFH
             MOVWF   D200_R2              ;内层寄存器
D200MS_LP1:  NOP
             NOP
             NOP
             NOP
             NOP
             NOP
             NOP
             DECFSZ  D200_R2
             GOTO    D200MS_LP1
             DECFSZ  D200_R1
             GOTO    D200MS_LP0
             RETLW   0

             end