Read a character from serial port and send back

[Pavithra]

Hi Engineers Garage and all

 

I have a query regarding serial communication. I need to read a character from serial port and send them back. Ive written the code but not getting expected result. Please u experts help me.. I would be very happy :]

This is my assembly code

 

ORG 000H
MOV TMOD,#20H
MOV TH1,#0FDH
MOV SCON,#50H
SETB TR1

r:JNB RI,R
    MOV A,SBUF
    MOV P1,A
    CLR RI
    SJMP R

HERE:JNB TI,HERE
CLR TI
AGAIN:MOV P2,SBUF
SJMP AGAIN
END

 

PLease guys help me and suggest me wat m i doin wrong .   waiting for ur reply

[Savio]

Hey Pavithra,

 

I tried simulating your code and there are some points you should note.

 

1. Use ‘ ACALL r ‘ to make a recieve function and end it with ‘ RET ‘. In your code ‘SJMP r’ will loop forever in the ‘r’ subroutine and never execute the sending subroutine.

 

2. The data you are recieving is on ‘P1’ , but you are transmitting data from ‘P2’ .

 

3. If you are simulating, check that the clock is set to 11.0592MHz only.

 

This is your code which I made some changes to, hope it helps.

 

ORG 000H
MOV TMOD,#20H
MOV TH1,#0FDH
MOV SCON,#50H
SETB TR1
ACALL r
ACALL t

r:JNB RI,R
    MOV A,SBUF
    MOV P1,A
    CLR RI
    RET

t:    MOV P1, A
    MOV SBUF, A
w:    JNB TI,w
    CLR TI
    
    RET
END

 

Regards.

[Pavithra]

thank you so much for ur suggestions.. Im gonna try this out and hope so it would work ..

 

with regards.

[Pavithra]

Sorry to say this, this code dint work.

[umar farrok]

try this code 

SCON=0X50;

TMOD=0X20;

TL1=TH1=0XFD;

TR1=1;

 inside main

while(RI==0);

{

RI=0;

msg=SBUF;

SBUF=msg;

while(TI==0);

TI=0;

}

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