89keya.asm

单片机开发资料光盘-双龙-686M.zip

cs	bit	p2.4
clk	bit	p2.3
dat	bit	p2.2
key	bit     p2.1

temp	  data	30h
cnt	  data	31h
send_buf  data	32h
rec_buf   data  33h
delayr	  data  34h

	org	0000h
	ajmp	reset
	org	80h
reset:
	mov	sp,	#10h                 ;设堆栈
	setb	cs                           ;初始化
	setb	key
	clr	clk
        mov	send_buf,#0a4h               ;清屏
	call	send
	setb	cs
wait:
	jb	key,	wait
main:
	mov	send_buf,#15h                ;接收键盘键值
	call	send
	call	receive
	setb	cs
	call	delay50u
	mov	send_buf,#0cfh               ;送键值显示
	call	send
	mov	send_buf,rec_buf
	call	send
	setb	cs
wait1:
	jnb	key,	wait1
	ajmp	wait

send:                               ;发送子程序
	mov	cnt,	#8
	clr	cs
	call	delay50u
send1:
	mov     a,	send_buf
	rlc	a
	mov	send_buf,a
	mov	dat,	c
	nop
 	nop
	setb	clk
	call	delay10u
	clr	clk
	call    delay10u 
	djnz	cnt,	send1
	clr	dat
	ret
receive:                                ;接收子程序 
	mov	cnt,	#8
	setb	dat
	call	delay50u
receive1:
	setb	clk
	call	delay10u
	mov	c,	dat
        mov	a,	rec_buf
	rlc	a
	mov	rec_buf,a
	nop
	nop
	nop
	clr	clk
	call	delay10u
	djnz	cnt,	receive1
	clr	dat
	ret
	
delay50u:                             ;延时子程序
	mov	delayr, #200
	djnz	delayr, $
	ret				
delay10u:
	mov	delayr, #40
	djnz	delayr, $
	ret
end