89spi.asm

来自「at89x52 spi 编程工具」· 汇编 代码 · 共 71 行

/***************************************************************
    spi.asm
***************************************************************/


RS232_R1                 EQU    30H
RS232_R2                 EQU    31H
RS232_W1                 EQU    32H
RS232_W2                 EQU    33H

RECEIVED                 BIT    10H

       ORG         0000H
       AJMP        INIT
       ORG         0023H
       LJMP        RECEIVE
       ORG         30H

INIT:  
	MOV		SP,	#60H
	MOV     SCON,  #40H
	MOV     TMOD,  #20H
	MOV     PCON,  #0
	MOV     TH1,   #0FDH
	MOV     TL1,   #0FDH

	SETB    REN
	SETB    TR1
	SETB    ES
	SETB    EA
	CLR     A
    SJMP    LOOP

LOOP:   NOP
        JNB     RECEIVED,   LOOP    ;JNB表示直接寻址位为零转移
REC:    
	CLR     RECEIVED
	MOV		R1,#0FH
	
LL:	SETB	P3.7
	SETB	P3.6
	MOV		P0,R1
	CLR		P3.7
	MOV		A,P0
	SETB	P3.7
	MOV		RS232_W1,A
	LCALL	SEND232
	
	DJNZ	R1,LL
	SJMP	LOOP
SEND232:
	MOV     A,    RS232_W1
	MOV     SBUF,  A
	JNB     TI,    $
	CLR     TI
	RETI
RECEIVE:
	PUSH    ACC
	PUSH    PSW
	JNB     RI,   UU
	MOV     A,    SBUF
	CLR     RI
	MOV     RS232_R1,    A
	SETB    RECEIVED
UU:
	POP     PSW
	POP     ACC
	RETI
END