[SOLVED] GPS Communication to pic

[Mani Yuvan]

when i connect gps with micro it works and display the letter but it shows
" $GPRMC,123519.09 " but i want extract the $GPGGA data.so how to i extract these data from gps

- - - Updated - - -

here below the code i attached. when i run this code in hardware the lcd display incorrectly.I also include the output pic also. please see and give the suggestion to me.

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Code C - [expand]
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#include<p18f452.h>
#include"H:\RECovery RObot\header files\lcd.h"
#include"H:\RECovery RObot\header files\delay.h"
#include"H:\RECovery RObot\header files\motor.h"
#pragma config OSC=HS, OSCS=OFF
#pragma config DEBUG=OFF, LVP=OFF, STVR=OFF
#pragma config WDT=OFF
#pragma config BOR=OFF, PWRT=ON
unsigned char rx_data(void);
unsigned char longi_data[12];
unsigned char lati_data[12];
unsigned char data;
void main()
{
unsigned char a[]={0X38,0X01,0X0c,0X06,0X80},i;
TRISD=0;
ADCON1=0X07;
TRISEbits.TRISE0=0;
TRISEbits.TRISE1=0;
TRISEbits.TRISE2=0;
//TRISC=0;
en=0;
for(i=0;i<5;i++)
{
lcdcmd(a[i]);
Msdelay(2);
}
RCSTA=0X90;
SPBRG=129; // Fill SPBRG register to set the baud rate
TXSTAbits.TXEN=1;
RCSTAbits.SPEN=1; 
while(1)
{
data=rx_data(); // Check the string '$GPGGA,'
if(data=='$')
{
data=rx_data();
if(data=='G')
{
data=rx_data();
if(data=='P');
{
data=rx_data();
if(data=='G');
{
data=rx_data();
if(data=='G')
{
data=rx_data();
if(data=='A')
{
data=rx_data();
if(data==',')
{
data=rx_data();
while(data!=',')
data=rx_data();
if(data==',')
{
for(i=0;data!='N';i++)
{
data=rx_data();
lati_data[i]=data; // Store the Latitude data
}
}
data=rx_data();
if(data==',')
{
for(i=0;data!='E';i++)
{
data=rx_data();
longi_data[i]=data; // Store the Longitude data
}
}
i=0;
while(i<11)
{
lcddata(lati_data[i]); // Print the Latitude data
Msdelay(2);
i++;
}
i=0;
lcdcmd(0xc0);
while(i<12)
{
lcddata(longi_data[i]); // Print the Longitude data
Msdelay(2);
i++;
}
}
}
}
}
}
}
}
}
Msdelay(1000);
for(i=0;i<12;i++)
{
data=0;
lati_data[i]=0;
longi_data[i]=0;
}
 
}
unsigned char rx_data(void)
{
while(PIR1bits.RCIF==0); // Wait until RCIF gets low
return RCREG; // Store data in Reception register
}#include<p18f452.h>
#include"H:\RECovery RObot\header files\lcd.h"
#include"H:\RECovery RObot\header files\delay.h"
#include"H:\RECovery RObot\header files\motor.h"
#pragma config OSC=HS, OSCS=OFF
#pragma config DEBUG=OFF, LVP=OFF, STVR=OFF
#pragma config WDT=OFF
#pragma config BOR=OFF, PWRT=ON
unsigned char rx_data(void);
unsigned char longi_data[12];
unsigned char lati_data[12];
unsigned char data;
void main()
{
unsigned char a[]={0X38,0X01,0X0c,0X06,0X80},i;
TRISD=0;
ADCON1=0X07;
TRISEbits.TRISE0=0;
TRISEbits.TRISE1=0;
TRISEbits.TRISE2=0;
//TRISC=0;
en=0;
for(i=0;i<5;i++)
{
lcdcmd(a[i]);
Msdelay(2);
}
RCSTA=0X90;
SPBRG=129; // Fill SPBRG register to set the baud rate
TXSTAbits.TXEN=1;
RCSTAbits.SPEN=1; 
while(1)
{
data=rx_data(); // Check the string '$GPGGA,'
if(data=='$')
{
data=rx_data();
if(data=='G')
{
data=rx_data();
if(data=='P');
{
data=rx_data();
if(data=='G');
{
data=rx_data();
if(data=='G')
{
data=rx_data();
if(data=='A')
{
data=rx_data();
if(data==',')
{
data=rx_data();
while(data!=',')
data=rx_data();
if(data==',')
{
for(i=0;data!='N';i++)
{
data=rx_data();
lati_data[i]=data; // Store the Latitude data
}
}
data=rx_data();
if(data==',')
{
for(i=0;data!='E';i++)
{
data=rx_data();
longi_data[i]=data; // Store the Longitude data
}
}
i=0;
while(i<11)
{
lcddata(lati_data[i]); // Print the Latitude data
Msdelay(2);
i++;
}
i=0;
lcdcmd(0xc0);
while(i<12)
{
lcddata(longi_data[i]); // Print the Longitude data
Msdelay(2);
i++;
}
}
}
}
}
}
}
}
}
Msdelay(1000);
for(i=0;i<12;i++)
{
data=0;
lati_data[i]=0;
longi_data[i]=0;
}
 
}
unsigned char rx_data(void)
{
while(PIR1bits.RCIF==0); // Wait until RCIF gets low
return RCREG; // Store data in Reception register
}

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[Simao.Berkof]

Sometimes you have to program the gps module to send you the sentence you need. Look up the gps datasheet and verify which command is required to enable GGA sentence, you may also disable the sentences you don´t need.
Hope it helps.

Simao

 

[betwixt]

That is horribly convoluted code with at least 9 nested 'if' statements. A FAR better method is to capture everything starting with '$' into a character buffer and then use a string compare instruction to check if it contains the prefix you are looking for. From there is it easy to copy the remainder of the buffer to the LCD.

Brian.