ex8-5a.asm

《增强型8051单片机实用开发技术》例程代码

$INCLUDE (STC12C5A.INC) ;包含STC12C5A60S2单片机寄存器定义文件
BITTEST	DATA	20H
S2TIbit	BIT		01H
S2RIbit	BIT		00H
ORG		0000H
		LJMP	MAIN
		ORG		0043H
		LJMP	UART2_ISR
		ORG		0100H
MAIN:	MOV		SP,#60H			;设置堆栈
		MOV		S2CON,#50H		;01010000 8位可变波特率，无奇偶校验位,允许接收
		MOV		BRT,#0FDH
		MOV		AUXR,#11H     	;BRTR = 1(启动BRT), S1BRS = 1
		MOV    IE2, #01H      	;允许串口2中断,ES2=1
		SETB 	EA
		SJMP	$
UART2_ISR:
		MOV 	BITTEST,S2CON	;将S2CON保存到20H单元以便位寻址
    	JBC 	S2RIbit,RDATA	;若是接收中断，则将S2RI清零
		CLR		S2TIbit			;否则就是发送中断，将S2TI清零
		LJMP	RETURN
RDATA:	MOV		A,S2BUF		;读取收到的数据
		CPL		A
		MOV		S2BUF ,A		;将收到的数据发送回去
RETURN:MOV	S2CON,BITTEST 		;该语句可以起到中断标志清零的作用
		RETI
		END