越限报警.txt

单片机c51实验 越限报警

 	CODE SEGMENT
      	     ASSUME CS:CODE
 	ORG 100H
 START: MOV DX,04A0H
	MOV AL,00H
 	OUT DX,AL
	MOV DX,04B0H ;	简单I/O口74LS244
 TEST:  IN  AL,DX
	AND AL,01H
	JZ  TEST
	MOV DX,04A0H
	IN  AL,DX
	MOV AH,AL
        CMP AH,0FEH;上限
	JA  BRAN1
 L1:	CMP AH,0F0H;上复限
	JNB DONE
        MOV DX,04C0H
	MOV AL,00H
	OUT DX,AL

        CMP AH,01H;下限
	JB  BRAN2
 L2:    CMP AH,10H; 下复限
	JNA DONE
        MOV DX,04C0H
     	MOV AL,00H
	OUT DX,AL
        JMP DONE
        
 BRAN1: MOV DX,04C0H ; 74LS273
	MOV AL,01H;
	OUT DX,AL
	JMP L1
 BRAN2: MOV DX,04C0H
	MOV AL,10H
	OUT DX,AL
	JMP L2 
 DONE:  JMP START
	CODE ENDS
	END START