ad.asm

来自「采用C51语言完成基于74HC595的串口键盘与LED指示灯单元设计」· 汇编 代码 · 共 39 行

PUBLIC	AD
DE	SEGMENT CODE
RSEG	DE

AD:   
	CLR	P1.6	;/CS
	JNB	P3.2,$	;DOUT

	MOV	R2,#04H
	MOV A,#00H
	CLR C
HIGH_4BIT:  	
	SETB P1.7	;SCLK
	NOP
	CLR	P1.7
    NOP
    MOV	C,P3.2
    RLC	A
    DJNZ R2,HIGH_4BIT
    MOV R6,A	;return high 4bit

    MOV	A,#00H
    MOV	R2,#08H
	CLR	C	 //
LOW_8BIT:
    SETB P1.7
    NOP
    CLR	P1.7
    NOP
    MOV	C,P3.2
    RLC	A
    DJNZ R2,LOW_8BIT
    MOV	R7,A    ;return low byte
    SETB P1.7
    NOP
    CLR	P1.7
    SETB P1.6
    RET
    END