Điều khiển Stepper Motor

[picfan]

Em là thành viên mới, em muốn hỏi về điều khiển Stepper motor sử dụng PIC6F84. Em có 1 đoạn code, sử dụng 3 nút bấm điều khiển quay ben trái, quay ben phải, va dừng lại. em muốn thêm một nút điều khiển cho tự quay có chu kỳ, quay hết một vòng rồi quay ngược lại (vì quay liên tục sẽ bị rối dây cáp).

Đây là code:

 ;********************************************************

        list            p=pic16f84a
        include         p16f84a.inc
        __config _hs_osc & _wdt_off & _pwrte_on & _cp_off

;****************  Label Definition  ********************
        cblock  h'0c'
mode                            ;Operation mode
                                ;0=stop 1=right 2=left
count1                          ;Wait counter
count2                          ;Wait counter(for 1msec)
        endc

rb0     equ     0               ;RB0 of PORTB
rb1     equ     1               ;RB1 of PORTB
rb2     equ     2               ;RB2 of PORTB
rb5     equ     5               ;RB5 of PORTB
rb7     equ     7               ;RB7 of PORTB

;****************  Program Start  ***********************
        org     0               ;Reset Vector
        goto    init
        org     4               ;Interrupt Vector
        clrf    intcon          ;Clear Interruption reg

;****************  Initial Process  *********************
init
        bsf     status,rp0      ;Change to Bank1
        clrf    trisa           ;Set PORTA all OUT
        movlw   b'00100111'     ;RB0,1,2.5=IN RB7=OUT
        movwf   trisb           ;Set PORTB
        movlw   b'10000000'     ;RBPU=1 Pull up not use
        movwf   option_reg      ;Set OPTION_REG
        bcf     status,rp0      ;Change to Bank0
        clrf    mode            ;Set mode = stop
        clrf    count1          ;Clear counter
        clrf    count2          ;Clear counter
        movlw   b'00000101'     ;Set PORTA initial value
        movwf   porta           ;Write PORTA
        bsf     portb,rb7       ;Set RB7 = 1
        btfsc   portb,rb5       ;RB5 = 0 ?
        goto    $-1             ;No. Wait

start
;*************  Check switch condition  *****************
        btfsc   portb,rb1       ;RB1(stop key) = ON ?
        goto    check1          ;No. Next
        clrf    mode            ;Yes. Set stop mode
        goto    drive           ;No. Jump to motor drive
check1
        btfsc   portb,rb2       ;RB2(right key) = ON ?
        goto    check2          ;No. Next
        movlw   d'1'            ;Yes. Set right mode
        movwf   mode            ;Save mode
        goto    drive           ;No. Jump to motor drive
check2
        btfsc   portb,rb0       ;RB0(left key) = ON ?
        goto    drive           ;No. Jump to motor drive
        movlw   d'2'            ;Yes. Set left mode
        movwf   mode            ;Save mode

;********************  Motor drive  *********************
drive
        movf    mode,w          ;Read mode
        bz      start           ;mode = stop
        bsf     portb,rb7       ;Set RB7 = 1
        btfsc   portb,rb5       ;RB5 = 0 ?
        goto    $-1             ;No. Wait
        movlw   d'5'            ;Set loop count(5msec)
        movwf   count1          ;Save loop count
loop    call    timer           ;Wait 1msec
        decfsz  count1,f        ;count - 1 = 0 ?
        goto    loop            ;No. Continue
        bcf     portb,rb7       ;Set RB7 = 0
        btfss   portb,rb5       ;RB5 = 1 ?
        goto    $-1             ;No. Wait
        movf    porta,w         ;Read PORTA
        sublw   b'000000101'    ;Check motor position
        bnz     drive2          ;Unmatch
        movf    mode,w          ;Read mode
        sublw   d'1'            ;Right ?
        bz      drive1          ;Yes. Right
        movlw   b'00001001'     ;No. Set Left data
        goto    drive_end       ;Jump to PORTA write
drive1
        movlw   b'00000110'     ;Set Right data
        goto    drive_end       ;Jump to PORTA write
;-------
drive2
        movf    porta,w         ;Read PORTA
        sublw   b'000000110'    ;Check motor position
        bnz     drive4          ;Unmatch
        movf    mode,w          ;Read mode
        sublw   d'1'            ;Right ?
        bz      drive3          ;Yes. Right
        movlw   b'00000101'     ;No. Set Left data
        goto    drive_end       ;Jump to PORTA write
drive3
        movlw   b'00001010'     ;Set Right data
        goto    drive_end       ;Jump to PORTA write
;-------
drive4
        movf    porta,w         ;Read PORTA
        sublw   b'000001010'    ;Check motor position
        bnz     drive6          ;Unmatch
        movf    mode,w          ;Read mode
        sublw   d'1'            ;Right ?
        bz      drive5          ;Yes. Right
        movlw   b'00000110'     ;No. Set Left data
        goto    drive_end       ;Jump to PORTA write
drive5
        movlw   b'00001001'     ;Set Right data
        goto    drive_end       ;Jump to PORTA write
;-------
drive6
        movf    porta,w         ;Read PORTA
        sublw   b'000001001'    ;Check motor position
        bnz     drive8          ;Unmatch
        movf    mode,w          ;Read mode
        sublw   d'1'            ;Right ?
        bz      drive7          ;Yes. Right
        movlw   b'00001010'     ;No. Set Left data
        goto    drive_end       ;Jump to PORTA write
drive7
        movlw   b'00000101'     ;Set Right data
        goto    drive_end       ;Jump to PORTA write
;-------
drive8
        movlw   b'00000101'     ;Compulsion setting

drive_end
        movwf   porta           ;Write PORTA
        goto    start           ;Jump to start

;*************  1msec Timer Subroutine  *****************
timer
        movlw   d'200'          ;Set loop count
        movwf   count2          ;Save loop count
tmlp    nop                     ;Time adjust
        nop                     ;Time adjust
        decfsz  count2,f        ;count - 1 = 0 ?
        goto    tmlp            ;No. Continue
        return                  ;Yes. Count end

;********************************************************
;             END of Stepper Motor controller
;********************************************************

        end

Em cảm ơn