PIC 单片机控制步进电机源程序

; STEP_3.ASM (12C508 / 12C509)

;

; Controls a stepping motor driver on GPIO bits 4, 2, 1 and 0.

;

; The direction is controlled by a switch on GPIO bit 3. Bit 5 is not

used.

;

; (Typical drivers might include a ULN2803 Octal Driver, 2N2222 or TIP122

; transistors or power FETs. See Parallel Port Manual - Vol 1).

;

; Outputs patterns 0x01, 0x03, 0x02, 0x06, 0x04, 0x0c, 0x08, 0x09, 0x01,

; .. in sequence to advance stepping motor in one direction. This is

; achieved by causing INDEX to advance from 0 to 7, to 0, etc and

; mapping the INDEX into a pattern which is then output on bits 4, 2, 1

; and 0 of GPIO.

;

; Note that GPIO bit 3 is not used. Thus, prior to outputting, bit 3

; of PATT is copied to the bit 4 position.

;

; Motor is advanced in the other direction by causing INDEX to move in

; the opposite direction; 7 to 0 to 7, etc.

;

; Switch on GPIO, Bit 3 is read between each output to the stepping

; motor to determine whether INDEX is to be incremented (0-7, 0) or

; decremented.

;

; The delay in between steps determines the speed of the stepper. In

; this program it is 25 msecs.

LIST P=PIC12C509

__CONFIG 0EH ; MCLR - dis, CP - dis, WDT - dis, FOSC - int

#include

CONSTANT BASE_VAR=07H

INDEX EQU BASE_VAR+0

PATT EQU BASE_VAR+1

LOOP1 EQU BASE_VAR+2 ; for timing loop

LOOP2 EQU BASE_VAR+3

ORG 000H

MOVLW 080H ; GPWU disabled, GPPU enabled, other bits not used

OPTION

MOVLW B'101000'

TRIS GPIO ; Bit 3 input, Bits 4, 2, 1 and 0 ouputs

CLRF INDEX ; start INDEX at zero

READ_SW:

BTFSC GPIO, 3 ; read direction switch

GOTO FORWARD

GOTO REVERSE

FORWARD:

INCF INDEX, F ; increment the index

MOVLW .8

SUBWF INDEX, W ; and test if equal to 8

BTFSC STATUS, Z

CLRF INDEX ; if at 8, set to 0

GOTO ONE_STEP

REVERSE:

DECF INDEX, F ; decrement the index

MOVLW 0FFH

SUBWF INDEX, W ; test if at 0xFF

BTFSC STATUS, Z

GOTO REVERSE_1 ; if at FF, then reset to 7

GOTO ONE_STEP

REVERSE_1:

MOVLW .7

MOVWF INDEX

GOTO ONE_STEP

ONE_STEP:

MOVF INDEX, W ; copy count into w

CALL GEN_PATT ; returns the correct pattern in w

MOVWF PATT ; save it

BTFSS PATT, 3 ; move bit 3 to bit 4

BCF PATT, 4

BTFSC PATT, 3

BSF PATT, 4

MOVF PATT, W

MOVWF GPIO

CALL DELAY ; 25 msecs

GOTO READ_SW

;;;;;;

GEN_PATT ; maps INDEX into appropriate stepping motor pattern

MOVF INDEX, W

ADDWF PCL, F ; add w to the program counter

RETLW 01H ; stepping motor patterns

RETLW 03H

RETLW 02H

RETLW 06H

RETLW 04H

RETLW 0CH

RETLW 08H

DELAY: ; provides nominal 25 msec delay

MOVLW .25

MOVWF LOOP1

OUTTER:

MOVLW .110

MOVWF LOOP2

INNER:

CLRWDT

NOP

NOP

NOP

NOP

NOP

DECFSZ LOOP2, F

GOTO INNER

DECFSZ LOOP1, F

GOTO OUTTER

RETURN

END