GSM remote control and PDU format

Hello all,
I managed to build an sms controller using text mode but now I m trying to build one that uses sms in pdu format (because is harder and harder for me to find phones that use text mode)
I need to decode the message because the configuration of phone to which the messages are send back is configured by sms.
I also need to encode in pdu format because I send messages with data from sensor.
For the moment I haven't managed to find how to decode pdu format using the libs I managed to find.
Did anyone managed to work with pdu format?

PS:
Here are some of my projects with GSM controller:

This page might help you...
http://www.smartposition.nl/resources/sms_pdu.html
consider using 7-bit ascii only for simplicity of implementation.

This page might help you...
http://www.smartposition.nl/resources/sms_pdu.html
consider using 7-bit ascii only for simplicity of implementation.

Ajay Bhargav

This is what I get from my phone (Sony Ericsson T230)

+CMGL: 1,1,,24
07910447946400F0240B910447165231F600003130910220148005537A584E07
OK

I suppose that the best solution is to detect in to my string the sequence +CMGL and after that to put in an array the piece that contains the message and after that I will decode it

decoding is the hardest part. You need to first store in array and then convert ascii to hex and finally get the sms out of PDU bytes. I suggest you to use CMGR command instead of CMGL as CMGL will have longer list of sms whereas CMGR will give you only the sms you request to read.

Ok I will start working on this and I will inform you how it works

Hi.
Good news.I've managed to create some C code that I tested for the moment in VisualStudio and it seems to work.
I will start the implementation on the MCU
Here is the code for decoding :

#include "stdafx.h"
#include<iostream>

#include <string.h>

#include <conio.h>

using namespace std;

//-------------------------------------------------------------------------------------------------------------------------------------------------
void IntToHexString(short int len, char *slen)
{
  char hexchar[]={'0','1','2','3','4','5','6','7','8','9',
                  'A','B','C','D','E','F'};
  sprintf(slen, "%c%c",hexchar[(len & 0xF0)>
>
4],hexchar[len & 0x0F]);
}


void HexStrToInt(char *str, int * result)
{
  //char HexChars[]={'0','1','2','3','4','5','6','7','8','9','A','B','C','D','E','F'};
  int high=0;
  int low=0;
  if ((str[0]>
='0') && (str[0]<='9')) high=str[0]-'0';
  if ((str[0]>
='A') && (str[0]<='F')) high=str[0]-'A'+10;
  if ((str[0]>
='a') && (str[0]<='f')) high=str[0]-'a'+10;
  if ((str[1]>
='0') && (str[1]<='9')) low=str[1]-'0';
  if ((str[1]>
='A') && (str[1]<='F')) low=str[1]-'A'+10;
  if ((str[1]>
='a') && (str[1]<='f')) low=str[1]-'a'+10;
   *result=high*16+low;
}


void EncodePDU7BitData(char* input, char*output)
{
  int pos=0;
  int c1, c2, r, temp;
  int i;
  int inputlen;
  inputlen=strlen(input);
  IntToHexString(inputlen, output+pos);
  pos+=2;
  for (i=0;i<inputlen;i++)
  {
	if (i==inputlen)
	  c2=0;
	else
	  c2=input[i+1] & 0x7F;
	c1=input[i] & 0x7F;
	r=(i+1) % 8;
	if (r!=0)
	{
	  temp=((c1 >
>
 (r - 1)) | (c2 << (8-r)))& 0xFF;
	  IntToHexString(temp, output+pos);
	  pos+=2;
	}
  }
}
void DecodePDU7BitData(char* input, char*output)
{
  int len, temp;
  char tempstr1[3], tempstr2[3];
  unsigned int tempval,i, j, pos;
  int temp1, temp2;
  int inputlen;

  inputlen=0;
  while ((input[inputlen]!=10)&&(input[inputlen]!=13)) inputlen++;
  
  
  pos=0;
  HexStrToInt(input, &len);
  j=2;
  for (i=1;i<=((inputlen-2) /2);i++)
  {
	if ((i %7)==1)
	{
	  HexStrToInt(input+j, &temp);
	  output[pos]=(temp & 0x7F);
	  //if (output[pos]==0) output[pos]=' ';
	  pos++;
	}
	else if ((i % 7) ==0)
	{
	  tempstr1[0]=input[j];tempstr1[1]=input[j+1];tempstr1[2]=0;
	  tempstr2[0]=input[j-2];tempstr2[1]=input[j-1];tempstr2[2]=0;
	  HexStrToInt(tempstr1, &temp1);
	  HexStrToInt(tempstr2, &temp2);
	  tempval=temp1*0x100+temp2;
	  output[pos]=(tempval>
>
2)& 0x7F;
	  //if (output[pos]==0) output[pos]=' ';
	  pos++;

	  output[pos]=(tempval>
>
9)&0x7F;
	  //if (output[pos]==0) output[pos]=' ';
	  pos++;
	}
	else
	{
	  tempstr1[0]=input[j];tempstr1[1]=input[j+1];tempstr1[2]=0;
	  tempstr2[0]=input[j-2];tempstr2[1]=input[j-1];tempstr2[2]=0;
	  HexStrToInt(tempstr1, &temp1);
	  HexStrToInt(tempstr2, &temp2);
	  tempval=temp1*0x100+temp2;

	  output[pos]=(tempval >
>
 (9 - (i % 7))) & 0x7F;
	  //if (output[pos]==0) output[pos]=' ';
	  pos++;
	}
	j+=2;
  }
  output[len]=0;
}
//-------------------------------------------------------------------------------------------------------------------------------------------------



int _tmain(int argc, _TCHAR* argv[])
{
	char *string_position = 0;
	char str_res_hour[100];	
	char upper[100];	
//	char ReadBuffer[100] = "05537A584E07";
	int i = 0;
	//char ReadBuffer[100] = "+CMGL: 1,1,,24 07910447946400F0240B910447165231F600003130910220148005537A584E07";
/*	if (strstr(ReadBuffer, "+CMGL") != 0)
	{

				string_position = strstr(ReadBuffer, "+CMGL");
				strncpy(str_res_hour, string_position + 69,20);
				str_res_hour[21] = '\0';
	}
*/

	DecodePDU7BitData("08737A584E8FC966",str_res_hour);
	//_strupr(str_res_hour);
	while (str_res_hour[i])
	{
		upper[i]=toupper(str_res_hour[i]);
		i++;
	}
	upper[i]='\0';
	puts(upper);
	_getch();

	return 0;
}

I've got a new question it is possible to send a SMS without adding SMSC number in the PDU package?

I've the answer myself

"It is possible to tell the GSM/GPRS modem or mobile phone to use the SMSC number specified by the AT command +CSCA (command name in text: Service Centre Address) for sending SMS messages. Just assign the value 0x00 to the first sub-field and omit the second and third sub-fields, i.e. the SMSC part becomes:"

haha.. congrats first of all for progress you've made. Do share your updates with us If you want I will host your project on this website. It will be helpful for many others..