SIM908 GPS not working

[Mithun_K_Das]

I'm using SIM908 module to gate the GPS data. But there is no data from the module.

I tried with all the commands it may required to get the data. But...

AT+CGPSPWR=1

OK
AT+CGPSRST=1

OK

AT+CGPSINF=0

0,0.000000,0.000000,0.000000,20101010000127.000,0,0,0.000000,0.000000
OK

there is all zero... I'm using a Active antenna of 3-5V and 1575.42MHz. And I checked the module pin GPS_VANT, its 3.8V what is sufficient for this active antenna I think. But there is no output. First I tried with RF jack to connect the antenna with the module. but guessing it is faulty, I soldered the antenna directly. But unfortunately it is still not responding....

What may be the error?

 

[milan.rajik]

You should place the GPS antenna outside. Indoor it will not work.

 

[Mithun_K_Das]

[Moved]GPS is always 00000 with SIM908 module

I was working with GPS with SIM908 module for last few weeks. Also posted before that my GPS is not working in another thread (https://www.edaboard.com/threads/327397/#post1398892). As friends suggested, I placed the GPS antena outside. But there is no result. Here is my code what I was trying...

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Code C - [expand]
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/*******************************************************************************
*                   Program for 'GPS Position Tracker for Car accident'        *
*                          Compiler: MicroC Pro for PIC v.5.6.1                *
*                         Program Written by Engr. Mithun K. Das               *
*                        e-mail: [email]mithun060@gmail.com[/email]; 01722448270              *
*                          MCU: PIC16F690; X-Tal:8MHz(internal)                *
*                                     16-Dec,2014                              *
*******************************************************************************/
 
/*
 
$GPGGA,025526.000,0653.409140,N,07954.150015,E,1,7 ,1.08,22.013,M,-96.608,M,,*4D
$GPGLL,0653.409140,N,07954.150015,E,025526.000,A,A *58
$GPGSA,A,3,21,29,18,24,22,25,15,,,,,,1.98,1.08,1.6 7*0F
$GPGSV,4,1,14,21,58,020,36,14,56,246,25,29,38,173, 36,18,32,354,36*7E
$GPGSV,4,2,14,24,30,071,49,22,25,317,34,06,19,304, 20,25,11,157,33*7E
$GPGSV,4,3,14,15,06,035,32,03,04,310,,31,03,205,,3 0,00,240,*78
$GPGSV,4,4,14,42,,,39,50,,,39*7F
$GPRMC,025526.000,A,0653.409140,N,07954.150015,E,0 .000,115.0,260313,,,A*6F
$GPVTG,115.0,T,,M,0.000,N,0.000,K,A*08
$GPZDA,025526.000,26,03,2013,,*57
 
*/
 
unsigned char text[64];
char *string;
int i = 0, latitude, longitude;
unsigned short ready;
short checkGPS=0;
 
 
 
void UART_Write_CText(const char *cptr)
{
    char chr;
    for ( ; chr = *cptr ; ++cptr ) UART1_Write(chr);
}
 
void GPS_Int(void);
void SMS_Int(void);
 
void interrupt() 
{
    if(INTF_bit)
    {
       checkGPS = 1;
       INTF_bit = 0;//clear flag
    }
    
    if (RCIF_bit == 1)
    {       // If interrupt is generated by RCIF
            text[i] = UART1_Read(); // Read data and store it to txrt string
            i++;             // Increment string index
            if (i >= 64)
            {                // If index = 768,
               i = 0;        //   set it to zero
               ready = 1;    // Ready for parsing GPS data
            }
            RCIF_bit = 0;    // Set RCIF to 0
    }
}
 
void main() 
{
  ANSEL = 0x00;
  ANSELH = 0x00;//all digital
  ADCON0 = 0x00;
  ADCON1 = 0x07;//all digital
  
  TRISA2_bit = 1;//set as input
  
  UART1_Init(9600);//initialize UART at br 9600 bps
  Delay_ms(15000);// leave some time for UART
  
  RCIE_bit = 1; // Enable USART Receiver interrupt
  GIE_bit = 1; // Enable Global interrupt
  PEIE_bit = 1; // Enable Peripheral interrupt
  RCIF_bit = 0;//clear flag
  
  INTE_bit = 1;//enbalbe INT
  INTEDG_bit = 0;//falling edge
  INTF_bit = 0;// clear flag
  
  
  UART_Write_CText("ATE0\r");//Eco OFF
  UART1_Write((char)13);
  UART1_Write((char)10);
 
  SMS_Int(void);
  UART_Write_CText("GPS is ready to get data. Press the key to check GPS...");// ask for GPS
  Delay_ms(1000);
  UART1_Write((char)26);//send Ctrl+Z
  ready = 0;
 while(1)
 {
    //OERR_bit = 0;// clear Overrun Error bit
    //FERR_bit = 0;//clear Farming Error bit
 
   // Note: If I unmask these two Error bits, result become funny characters. So it is kept masked. 
 
    
    if(checkGPS==1)
    {
          GPS_Int(void);
          Delay_ms(3000);
          RCIE_bit = 1; // Enable USART Receiver interrupt
          RCIF_bit = 0;    // Set RCIF to 0
          i = 0;
          ready = 0;
          UART_Write_CText("AT+CGPSINF=0\r");// ask for GPS
          Delay_ms(3000);
          if(ready == 1)
          {               // If the data in text array is ready do:
              ready = 0;
              RCIE_bit = 0; // Disable USART Receiver interrupt
              SMS_Int(void);
              UART_Write_CText("GPS response:");
              for(i=0;i<64;i++)
              {
                  UART1_Write(text[i]);//Write each character one by one
                  Delay_ms(10);
              }
              UART1_Write_Text("\r");// leave an enter
              UART_Write_CText("Note: Press the button again if you wish to take another data now.");// ask for GPS
              Delay_ms(1000);
              UART1_Write((char)26);//send Ctrl+Z
 
              checkGPS = 0;
          }
     }
 
 }//while(1)
}//void main
 
void GPS_Int(void)
{
    UART_Write_CText("AT+CGPSPWR=1\r");//send AT+CGPSPWR=1 and Enter
    Delay_ms(500);
    UART_Write_CText("AT+CGPSRST=0\r");//select GPS mode, 1 = Autonomous, 0 = Cold
    UART_Write_CText("AT+CGPSOUT=0\r");//Disable nema data format
    Delay_ms(3000);//leave 3sec to GPS setup
}
 
void SMS_Int(void)
{
     UART_Write_CText("AT+cmgf=1\r");
     Delay_ms(500);
     UART_Write_CText("AT+cmgs=");
     UART1_Write((char)'"');
     UART_Write_CText("01722448270");
     UART1_Write((char)'"');
     UART1_Write((char)13);
     UART1_Write((char)10);
     Delay_ms(500);
}
//end of the program

---

Program Explanation:

The program will start with a initial delay of 15sec leaving some time for GPS and GSM network. Then it will send a SMS to my cell phone so that I understand the device is ready to get a GPS data. Then I press the button, and it start searching GPS and after getting a data, it sends a SMS to me with the result. If I press the button again, it will again search a result and SMS to me.



Check list of what I've already tried:

a. I checked the antenna voltage, its 3.8V.

b. I tried with nema mode with all the formats. Same result but only "$GPRMC,..." responds some data but not in format.

c. I checked the commands with PC COM port with AT commands... same result.

d. I connected the GPS antenna with proper jack in the antenna point, but same 0000000, so I directly soldered the antenna with the PCB. Some image is given below...

Here is the image:

Now, I'm asking for help who are experienced with the related topics. I'm still on it too and trying to find the error. Thanks in advance.

 

[Mithun_K_Das]

Another important point is, I'm using a battery of 8V then a LM1705 Regulator shunted with Tip122 for current boosting as the power source of the module. Also I tried with a 5V/16A Power supply, And a Li-ion Battery too. But all same result. 00000