pwm.asm

汇编程序

;FILENAME:PWM.ASM  
;内容: PWM脉宽调制(小直流电机转速控制实验)
PORT1	EQU	290H
PORT2	EQU    28BH
PORT3 	EQU    28AH
DATA 	SEGMENT
BUF1 	DW	?
BUF2  	DW	?
DATA  	ENDS
CODE 	SEGMENT
       	ASSUME  CS:CODE
START:	MOV  DX, PORT2
       	MOV  AL, 8BH
      	OUT  DX, AL           		;8255K口输入
LLL:  	MOV  AL, 80H
      	MOV  DX, PORT1
      	OUT  DX, AL         		;D/A 输出0V
       	PUSH DX
       	MOV  AH, 06H
       	MOV  DL, 0FFH
	INT  21H
       	POP  DX
      	JE   INTK            		;有无键按下
       	MOV  AH, 4CH
       	INT  21H              		;返回DOS
INTK: 	MOV  DX, PORT3
       	IN   AL, DX         		;读开关状态
       	TEST  AL, 01H
       	JNZ K0
       	TEST  AL, 02H
       	JNZ K1
      	TEST  AL, 04H
      	JNZ K2
       	TEST  AL, 08H
       	JNZ  K3
       	TEST  AL, 10H
       	JNZ  K4
       	TEST  AL, 20H
       	JNZ  K5
       	JMP   LLL
K0:   	MOV  BUF1, 0400H
       	MOV  BUF2, 0330H     		;置延时常数
DELAY:	MOV  CX, BUF1
DELAY1:	
	LOOP DELAY1
 	MOV  AL, 0FFH
     	MOV  DX, PORT1
     	OUT  DX, AL         		;D/A 输出5V
     	MOV  CX, BUF2
DELAY2:		
LOOP  DELAY2
      	JMP  LLL
K1:    MOV  BUF1, 0400H
        MOV  BUF2, 0400H
        JMP  DELAY
K2:   	MOV  BUF1, 0400H
      	MOV  BUF2, 0500H
       	JMP        DELAY
K3:    MOV      BUF1, 0400H
    	MOV  BUF2, 0600H
K4:   	MOV  BUF1, 0400H
      	MOV  BUF2, 0700H
      	JMP  DELAY
K5:   	MOV  BUF1, 0400H
       	MOV  BUF2, 0800H
      	JMP  DELAY
CODE   ENDS
        END  START