GPS-LPC2148

#include<lpc214x.h>
#include "stdio.h"
#include "lcd.h"
#include "uart.h"


/*  This function fetches a string from the serial port using UART_GetChar() function
** In case of GPS, the co-ordinate string starts with a character '$'
** And ends with a character '*' followed by CRC
*/
void GPS_string(unsigned char *temp)
{
 unsigned int i=0;
 do
 {
  temp[i] = uart0_receive();
 }
 while(temp[i++] != '*');    //while '*' character is not received, keep fetching the string
 temp[i] = '\0';       //add a NULL character at the end of the string
}


/* This function takes the latitude and longitude string pointers as the input parameters
** And displays them on the LCD in a proper fashion
*/
void GPS_display(unsigned char *lat, unsigned char *lon)
{
 unsigned int i;

 LCD_cmd(0x84);       //cursor on 1st line 5th position
 for(i=0;i<2;i++)
  LCD_data(*lat++);   //display degrees
 LCD_data('\'');     //degree symbol
 for(i=0;i<8;i++)    //display rest of the string
  LCD_data(*lat++);

 LCD_cmd(0xC4);     //cursor on 2nd line 5th position
 for(i=0;i<3;i++)
  LCD_data(*lon++);   //display degrees
 LCD_data('\'');     //degree icon
 for(i=0;i<8;i++)    //display rest of the string
  LCD_data(*lon++);   
}


/* In the main function, we will continuously keep checking the serial port for character '$'
** If the character '$' is received, fetch all the characters between '$' and '*'
** Extract the latitude and longitude details from the string and display it on the LCD
** Eg: $GPGGA,155635,3730.4379,N,02357.4137,E,1,04,5.6,3.8,M,34.5,M,,*41
*/
int main()
{
 unsigned char ch, temp[20],lat[10],lon[10];
 unsigned int i=0,j=0;
 PINSEL0=0x00000005;
 LCD_init();
 UartInit(9600);
 
 LCD_display(1,1,"GPS Program");   
 delay();
 LCD_cmd(0x01);       //Clear Display
 LCD_display(1,1,"LAT:");
 LCD_display(2,1,"LON:");
 while(1)
 {
  if((ch = uart0_receive()) == '$') //if '$' is received
  {
   GPS_string(temp);     //fetch all characters upto '*'
   if(temp[2] == 'G' && temp[3] == 'G' && temp[4] == 'A')
   {
    i=0;
    j=0;
    while(temp[i++] != ',');   //$GPGGA (ignore)
    while(temp[i++] != ',');  //Time Stamp (ignore)
    while(temp[i] != ',')   //Capture Latitude
     lat[j++] = temp[i++];
    while(temp[i++] != ',');  //North/South
    lat[j++] = temp[i++];
 
    j=0;
    while(temp[i++] != ',');
    while(temp[i] != ',')   //Capture Longitude
     lon[j++] = temp[i++];
    while(temp[i++] != ',');  //East/West
    lon[j++] = temp[i++];
            //(ignore the rest part of the string)
     GPS_display(lat,lon);   //display latitude and longitude on the LCD
   }
  }
 }
 return 0;
}