GSM Message Read Problem

arunbharathi.arasu · Jan 3, 2017

Dear all,

I facing problem while read message.

when i read msg some letters are missing.

+CMGR:"REC UNREAD","+918754449444","",""17/08/17,15:48:23"
Hi, this is message

The above is the message format and message what i get from GSM.
shows in Terminal.

but when i read this i got

+CMGR:"REC UNREAD","+918754449444","",""17/08/17,154823"
Hthi is mssg

Like this. letters are missing form time..
body of the message also missing.

I have checked by sending the data what i received.

Raj Gunaseelan · Jan 4, 2017

Hello Arun,

I understand that the GSM module works as expected. But it is on the microcontroller side that you are missing some characters.
1. Assuming you are using a microcontroller, what microcontroller are you using?
2. How are you handling UART receive? via. interrupt or by polling?
3. How do you handle the received characters? That is, can you explain how you receive the characters and buffer it to your array?

Regards,
Raj Gunaseelan James

arunbharathi.arasu · Jan 4, 2017

Dear Raj Gunaseelan ,

problem solved. thanks.

- - - Updated - - -

hi,

Now i can read first message properly.

But i cannot read second message.

- - - Updated - - -
main program inside while

Code:

while(1)    {
    if(msgflag==1)
    {
     MSG_READ();
     count=0;
    delay(1000);
    msgflag=0;
    }
}

My interrupt code is

Code:

unsigned char *ok="OK",*error="ERROR",*newmsg="+CMTI: "SM",1";

Code:

void interrupt uart_ISR()
{      
    if(RCIF==1)
    {
       Rx_data=RCREG;
       RCIF=0;
       if(Rx_data!= 0x0A)
       {
         Arraydata[count]= Rx_data; 
         count++;
       }
       else
       {
        Arraydata[count]=0;
        if(flag);
        else
        count=0;
       }
       
       arrayptr=Arraydata;
       if(flag)
           data=Arraydata;
       if(strstr(arrayptr,ok))
       {
           RC_BIT_Flag=1;
       }
       else if(strstr(arrayptr,error))
       {
           RC_BIT_Flag=0;   
       
       }
       else if(strstr(arrayptr,newmsg))
       {
          msgflag=1;
       }
    }
  
}

please let me if any error..

I can read ok,error,and first message but if i am reading secound message i cannot.

once i read message i will delete the message

Code:

void MSG_READ()
{   
    flag=1;
    trans_string("AT+CMGR=1\r"); 
    delay(500);
    flag=0;
    trans_string("AT+CMGD=1\r");
    delay(100);
}

here i used flag. because after message i received "ok".
so im using flag to stop "count=0" in interrupt.

Thanks in advance..

GSM Message Read Problem

arunbharathi.arasu

Full Member level 2

Raj Gunaseelan

Member level 1

arunbharathi.arasu

Full Member level 2

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