liping 

 初学者:各位高人，帮帮忙！
     我用的at89c2051,其中p1.0~p1.3接mt8880的四根数据线，p1.4接mt8880的时钟，p1.5
接rs0
p1.6接r/w,p1.7接了一个二极管的负端，用作指示。p3.7接mt8880的cs.
程序如下，其功能主要为发送。现在不能发送。状态位没有变化。 
                  
                        ORG 0000H
                       AJMP ST
                       ORG 0003H
                       AJMP TT
                       ORG 0050H
                    ST:ACALL DL1
                       ACALL DL1
                       CLR P3.7     ;片选
                       MOV A,#30H
                       MOV P1,A
                       MOV P1,A      ;写CRA
                       MOV A,#38H
                       MOV P1,A
                       MOV A,#30H     ;写CRB
                       MOV P1,A
                       SETB EA
                       SETB EX0
                       SETB P1.7
                  LOOP:NOP
                       SJMP LOOP
                    TT:NOP
                       MOV A,#3DH    ;设为中断允许，允许信号输出
                        MOV P1,A
                       MOV A,#30H
                       MOV P1,A
                       MOV A,#18H     ;写发送寄存器，写#8
                       MOV P1,A
                       ACALL DL1
                       ACALL DL1
                       ACALL DL1
                       MOV A,#0FFH
                       MOV P1,A
                       CLR P1.7
                       SETB P1.5
                       SETB P1.6
                       SETB P1.4      ;读状态寄存器
                   LOO:MOV A,P1
                       JNB ACC.1,LOO   ;如果ACC.1为1，则发送成功，这里有问题，程
序在这里跳。
                       ACALL DL1
                       SETB P1.7

                       NOP
                       MOV A,#11H
                       MOV P1,A
                       ACALL DL1
                       SETB P1.5
                       SETB P1.6
                       SETB P1.4
                  LOO1:MOV A,P1
                       JNB ACC.1,LOO1
                       ACALL DL1
                       SETB P1.7  ;这一段发#1

                       NOP
                       CLR P1.7
                       MOV A,#13H
                       MOV P1,A
                       ACALL DL1
                       SETB P1.6
                       SETB P1.5
                       SETB P1.4
                  LOO2:MOV A,P1
                       JNB ACC.1,LOO2
                       ACALL DL1       ;这一段发#3，

                       SETB P1.7
                       RETI
                   DL1:MOV R2,#4H
                  DL11:MOV R3,#0FFH
                  DL12:MOV R4,#0FFH
                    DL:DJNZ R4,DL
                       DJNZ R3,DL12
                       DJNZ R2,DL11
                       RET
                       END

发表时间:2002年6月13日13:59:00