Stepper motor control board

by Ranjith | November 17th, 2008.

Program 5:-

Now its time to start with harder programs. In this program all above facilities are there and two more are included increasing and decreasing RPM. Five switches and four LEDs are used. See the table for key functions and LED indications.

f equ 0fh                      ; direction flag
Org 00h
mov 30h, #3Ch      ; make a table of
mov 31h, #1Eh    ; four load values
mov 32h, #14h    ; for variable delay
mov 33h, #0Fh
mov r1, #30h       ;initial location in r1
mov r0,#01h    ; initialize key count
mov p1,#0ffh           ; P1 as input port
lop:   mov a,p1
cjne a,#0ffh,jmp
ajmp lop               ; loop until any key
; is pressed
jmp:     clr p0.0               ; indicates keypress
loop:    rrc a
jnc num             ; get key no.
inc r0
sjmp loop
num: acall dely            ; key debounce delay
setb p0.0

cjne r0,#01h,nxt      ; for 1st key
acall clkwise           ; rotate motor
sjmp over               ; clock wise
nxt: cjne r0,#02h,nxt2 ; for 2nd key
acall aclkwise           ; rotate anticlock
nxt2:   cjne r0,#03h,nxt3    ; for 3rd key
mov p2,#00h             ; stop motor
nxt3:   cjne r0,#04h,nxt4    ; for 4th key
acall incrpm                 ; increase RPM
jnb f, aclk         ; and continue to rotate
acall clkwise          ; motor in same
sjmp over               ; direction as it was
aclk:    acall aclkwise      ; running by
sjmp over             ; checking flag f
nxt3:   cjne r0,#05h,over     ; for 5th key
acall decrpm          ; decrease RPM and
jnb f, aclkw        ; again continue to
acall clkwise         ; rotate motor
sjmp over
aclks:   acall aclkwise
sjmp over

over:   mov r0,#01h
sjmp lop                ; jump to loop again
clkwise:
setb f                 ; for clkwise set directional
lop:   clr p0.1 ; flag
mov p2,#03h           ; at a time two coils
acall delay              ; energized in double
mov p2,#06h        ; coil excitation mode
acall delay
setb p0.1
mov p2,#0Ch
acall delay
mov p2,#09h
acall delay
mov p1, #0FFh    ; continue loop
mov a,p1              ; until any key is
cjne a,#0FFh,out       ; not pressed
sjmp lop
out:   ret
aclkwise:
clr f                 ; for aclkwise clear
lop1: clr p0.1              ; directional flag
mov p2,#03h
acall delay
mov p2,#09h             ; revert the pulse
acall delay           ; sequence for
setb p0.1
mov p2,#0Ch            ; anticlockwise
acall delay
mov p2,#06h
acall delay
mov p1, #0FFh
mov a,p1
cjne a,#0FFh,out1
sjmp lop1
out1: ret

incrpm:
clr p0.3             ; indication
cjne r1,#33h,incr   ; if max limit is
ajmp noin                ; reached no increase
incr: inc r1                    ; increase otherwise
acall dely
setb p0.3
noin: ret                      ; led stays on for max limit

decrpm:
clr p0.3              ; indication
cjne r1,#30h,incr ; if min limit is
ajmp noin             ; reached no decrease
incr: dec r1                ; decrease otherwise
acall dely
setb p0.3
noin: ret                   ; led stays on for min limit

delay:
mov 10h,@r1      ; load content of
lop2: mov r6,#FAh        ; address in r1
lop1:nop                   ; so it gives variable
nop                      ; delay every time
djnz 10h,lop1         ; to give variable
djnz r5,lop2              ; speed of motor
ret

dely:
mov r5,#0C8h ; load count 200
lop2: mov r6,#0FAh ; for 200ms delay
lop1:nop
nop
djnz r6,lop1
djnz r5,lop2
ret
end

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