Assembly code for DC Motor - PWM Pulse width Modulation


Sample code for DC Motor - PWM Pulse width Modulation.
Following code can be using for 8051 and 8052 ICs like: 89c51, 89c52, 89s51, 89s52, 89c2051. 

 

;=====================================================
;	Pin Definations
;=====================================================
mot1for         equ             a0h             ;address of Port 2.0
mot1rev         equ             a1h             ;address of port 2.1
mot2for         equ             a2h             ;address of port 2.2
mot2rev         equ             a3h             ;address of port 2.3
;=====================================================
;	Main Program starts from here
;=====================================================
 		call slowstart
		call slowstop
here             jmp here
;=====================================================
; Sub routines starts from here
;=====================================================
slowstart:		jnb 21h,mot2
		;goto mot2 if motor 2 is selected
                 	jnb 20h,rev_rise_on1
		;goto rev_rise_on1 if reverse direction is selected
		jnb 27h,slowstop_invert_dir
		;if motor is in reverse dir stop motor&rotate forward
		jnb 26h,slowstart_ret
		;if motor is in forward dir don't rotate forward again

		call mot1_for_start
slowstart_ret       ret
slowstop_invert_dir call mot1_rev_stop
		call mot1_for_start
		ret
rev_rise_on1       jnb 26h,slowstart_invert
		;don't start if motor is in forward direction
		jnb 27h,slowstart_ret1
		;don't start if motor is in reverse direction
		call mot1_rev_start
slowstart_ret1     ret
slowstart_invert   call mot1_for_stop
                call mot1_rev_start
                ret
mot2                jnb 20h,mot2_rev
		jnb 29h,slowstart_inv
		jnb 28h,slowstart_ret2
		call mot2_for_start
slowstart_ret2      ret
slowstart_inv   call mot2_rev_stop
                call mot2_for_start
                ret
mot2_rev            jnb 28h,slowstart_inve
		jnb 29h,slowstart_ret3
		call mot2_rev_start
slowstart_ret3      ret
slowstart_inve  call mot2_for_stop
                call mot2_rev_start
                ret
;=========================================================
slowstop            jnb 21h,for_rise_off_mot2
		jnb 20h,rev_rise_off_mot1
		jb 22h,slowstop_ret
		call mot1_for_stop
slowstop_ret        ret

rev_rise_off_mot1  jb 23h,slowstop_ret1
		call mot1_rev_stop
slowstop_ret1      ret

for_rise_off_mot2    jnb 20h,rev_rise_off_mot2
		jb 24h,slowstop_ret2
		call mot2_for_stop
slowstop_ret2        ret

rev_rise_off_mot2    jb 25h,slowstop_ret3
		call mot2_rev_stop
slowstop_ret3       ret
;=========================================================
mot1_for_start      clr mot1for       ;on period of pwm
		mov r2,30H
		djnz r2,$
		setb mot1for        ;off period of pwm
		mov r2,31H
		djnz r2,$
		djnz r3,mot1_for_start   ;repeat the loop 10 times
		mov r3,#10
		mov a,30H
		add a,# 5          ;increment on period by 10 microsec
		mov 30H,a
		mov a,31H
		subb a,# 5         ;decrement off period by 10 microsec
		mov 31H,a
		djnz r4,mot1_for_start   ;repeat the loop 20 times
		mov r4,#20
		clr mot1for
		clr 22h            ;sense stop key as mot1+for
		clr 26h            ;motor1+rev
		ret
;=========================================================
mot1_rev_start      clr mot1rev            ;on period of pwm
		mov r2,30H
		djnz r2,$
		setb mot1rev             ;off period of pwm
		mov r2,31H
		djnz r2,$
		djnz r3,mot1_rev_start    ;repeat the loop 10 times
		mov r3,#10
		mov a,30H
		add a,# 5               ;increment on period by 10 microsec
		mov 30H,a
		mov a,31H
		subb a,# 5         ;decrement off period by 10 microsec
		mov 31H,a
		djnz r4,mot1_rev_start  ;repeat the loop 20 times
		mov r4,#20
		clr mot1rev
		clr 23h		;sense stop key as mot1+rev
		clr 27h		;mot1+for
		ret
;=========================================================
mot2_for_start     clr mot2for      ;on period of pwm
		mov r2,30H
		djnz r2,$
		setb mot2for       ;off period of pwm
		mov r2,31H
		djnz r2,$
		djnz r3,mot2_for_start  ;repeat the loop 10 times
		mov r3,#10
		mov a,30H
		add a,# 5          ;increment on period by 10 microsec
		mov 30H,a
		mov a,31H
		subb a,# 5         ;decrement off period by 10 microsec
		mov 31H,a
		djnz r4,mot2_for_start  ;repeat the loop 20 times
		mov r4,#20
		clr mot2for
		clr 24h               ;sense stop key as mot2+for
		clr 28h               ;mot2+rev
		ret
;=========================================================
mot2_rev_start      clr mot2rev            ;on period of pwm
		mov r2,30H
		djnz r2,$
		setb mot2rev             ;off period of pwm
		mov r2,31H
		djnz r2,$
		djnz r3,mot2_rev_start       ;repeat the loop 10 times
		mov r3,#10
		mov a,30H
		add a,# 5          ;increment on period by 10 microsec
		mov 30H,a
		mov a,31H
		subb a,# 5         ;decrement off period by 10 microsec
		mov 31H,a
		djnz r4,mot2_rev_start ;repeat the loop 20 times
		mov r4,#20
		clr mot2rev
		clr 25h                 ;sense stop key as mot2+rev
		clr 29h                 ;mot2+for
		ret
;=========================================================
mot1_for_stop       clr mot1for   ;on period of pwm
		mov r2,31H
		djnz r2,$
		setb mot1for    ;off period of pwm
		mov r2,30H
		djnz r2,$
		djnz r3,mot1_for_stop   ;repeat the loop 10 times
		mov r3,#10
		mov a,30H
		add a,# 5          ;increment off period by 10 microsec
		mov 30h,a
		mov a,31h
		subb a,# 5         ;decrement on period by 10 microsec
		mov 31h,a
		djnz r4,mot1_for_stop   ;repeat the loop 20 times
		mov r4,#20
		setb mot1for
		setb 22h  ;don't sense stop key if moh1+for is not started
		setb 26h         ;if mot1+for then don't start mot1+rev
		ret
;=========================================================
mot1_rev_stop      clr mot1rev      ; on period of pwm
		mov r2,31h
		djnz r2,$
		setb mot1rev       ;off period of pwm
		mov r2,30h
		djnz r2,$
		djnz r3,mot1_rev_stop  ;repeat the loop 10 times
		mov r3,#10
		mov a,30h
		add a,# 5          ;increment off period by 10 microsec
		mov 30h,a
		mov a,31h
		subb a,# 5         ;decrement on period by 10 microsec
		mov 31h,a
		djnz r4,mot1_rev_stop   ;repeat the loop 20 times
		mov r4,#20
		setb mot1rev
		setb 23h
		;don't sense stop key if mot1+rev is not started
		setb 27h          ;if mot1+rev then don't start mot1+for
		ret
;=========================================================
mot2_for_stop        clr mot2for     ;on period of pwm
		mov r2,31h
		djnz r2,$
		setb mot2for      ;off period of pwm
		mov r2,30h
		djnz r2,$
		djnz r3,mot2_for_stop   ;repeat the loop 10 times
		mov r3,#10
		mov a,30h
		add a,# 5          ;increment off period by 10 microsec
		mov 30h,a
		mov a,31h
		subb a,# 5         ;decrement on period by 10 microsec
		mov 31h,a
		djnz r4,mot2_for_stop   ;repeat the loop 20 times
		mov r4,#20
		setb mot2for
		setb 24h ;don't sense stop key if mot2+for is not started
		setb 28h       ;if mot2+for then don't start mor2+rev
		ret
;=========================================================
mot2_rev_stop      clr mot2rev    ;on period of pwm
		mov r2,31h
		djnz r2,$
		setb mot2rev      ;off period of pwm
		mov r2,30h
		djnz r2,$
		djnz r3,mot2_rev_stop  ;repeat the loop 10 times
		mov r3,#10
		mov a,30h          ;increment off period by 10 microsec
		add a,# 5
		mov 30h,a
		mov a,31h
		subb a,# 5         ;decrement on period by 10 microsec
		mov 31h,a
		djnz r4,mot2_rev_stop   ;repeat the loop 20 times
		mov r4,#20
		setb mot2rev
		setb 25h  ;don't sense stop key if mot2+rev is not started
		setb 29h     ;if mot2+rev then don't start mot2+for
		ret
;=====================================================
;      	Program ENDS here
;=====================================================