按键控制p0口产生pwm.txt

模拟烘手机具有电机控制信号方式控制电机通过硬件检测

      PWMH  EQU  60H
	  PWMT  EQU  61H
	  COUNT EQU  63H
	  PWM   BIT  P0.0

	  ORG  0000H
	  AJMP  MAIN
	  ORG  000BH
	  LJMP  TIME0
	  ORG  0030H
MAIN: MOV  PWMT,#100              ;设PWM信号一个周期的总长度为100
      MOV  COUNT,#1
      MOV  TCON,#01H
	  SETB  EA
	  SETB  ET0
	  MOV  TH0,#0FFH
	  MOV  TL0,#12H
JIANCE:JB  P1.0,ZHONGSU            ;低速键按下,则附PWMH=10,即PWM信号的高电平数为10          
       MOV  PWMH,#10
  	   SETB  TR0
ZHONGSU: JB  P1.1,GAOSU            ;中速键按下,则附PWMH=50,即PWM信号的高电平数为50
       MOV  PWMH,#50                 
	   SETB  TR0
GAOSU: JB  P1.2,TINGZHI            ;高速键按下,则附PWMH=90,即PWM信号的高电平数为90  
       MOV  PWMH,#90
  	   SETB  TR0
TINGZHI:JB  P1.3,JIANCE            ;停止键按下,则置PWM信号为低电平
        CLR  TR0
        CLR  PWM
		AJMP  JIANCE
TIME0: INC  COUNT
       MOV  A,COUNT
	   CJNE A,PWMH,PANGDUAN         ;维持PWM信号的高电平到高电平的设定值
	   CLR  PWM                     ;到设定植后,PWM信号置低电平
PANGDUAN:CJNE  A,PWMT,EXIT          ;保持低电平信号,直到PWM信号周期的总长度后再置高电平
         SETB  PWM
		 MOV  COUNT,#1
   EXIT: MOV  TH0,#0FFH
         MOV  TL0,#12H
		 RETI
		 END