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Temas - Joscar
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1
« en: Sábado 21 de Agosto de 2004, 22:18 »
Hola a todos, mi duda es la siguiente: tengo el siguiente programa, pero existe unas intrucciones que no entiendo (GOTO $-1), por favor me lo pueden explicar. Gracias por sus respuestas el programa controla la velocidad, el sentido de giro (horario, antihorario) de un motor paso a paso. ;********************************************************
;
; Stepper Motor controller
;
;
;********************************************************
LIST P=PIC16F84A
INCLUDE P16F84A.INC
LIST
; P16F84A.INC Standard Header File, Version 2.00'(modify)
LIST
__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
VALUE
;************* 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
;VALUE
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
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