recently I've purchased this (adafruit ultimate GPS v3), and I've tried to interface it with PIC18f4550 to display longitude & latitude on an LCD.
the problem is that I only get the information clearly once, then when the code is repeating itself I got some undefined data and then It stop showing anything until I push the PIC18 reset button.
this is the code that I'm using
Code: Select all
// Last Modified: 27/04/2014
#include<p18f4550.h>
#include<delays.h>
#define FREQ 12000000 // this is crystal value
#define baud 9600 // baud rate that supported by GPS
#define spbrg_value (((FREQ/64)/baud)-1)
#pragma config PLLDIV = 3
#pragma config CPUDIV = OSC1_PLL2
#pragma config FOSC = HS
#pragma config MCLRE = ON
#pragma config WDT = OFF, DEBUG = OFF
#pragma config LVP = OFF
#pragma config PWRT = OFF
#pragma config PBADEN = OFF
#pragma config ICPRT = OFF
// defining LCD PORT
//---------------------------------
#define ldata PORTD
#define rs PORTCbits.RC0
#define rw PORTCbits.RC1
#define en PORTCbits.RC2
//Defining the LCD commands
//------------------------------------------
void lcdcmd(unsigned char value)
{
ldata = value;
rs = 0;
rw = 0;
en = 1;
Delay100TCYx( 30 );
en = 0;
}
//Defining the LCD display
//------------------------------------------
void lcddata(unsigned char value)
{
ldata = value;
rs = 1;
rw = 0;
en = 1;
Delay100TCYx( 30 );
en = 0;
}
// LCD initialization
// ------------------------------
void lcd_ini()
{
lcdcmd(0x38); //LCD matrix
Delay10KTCYx( 75 );
lcdcmd(0x0E); //Blink curser
Delay10KTCYx( 4 );
lcdcmd(0x01); //Clear LCD
Delay10KTCYx( 4 );
lcdcmd(0x06); //increment curser
Delay10KTCYx( 4 );
lcdcmd(0x80); //start at firs line, first position
Delay10KTCYx( 4 );
}
receiving data from GPS
//---------------------------------------
unsigned char rx_data(void)
{
while(PIR1bits.RCIF==0); // Wait until RCIF gets low
return RCREG; // Store data in Reception register
}
// ** THE MAIN FUNCTION **
void main()
{
TRISD = 0; //Set it output for the LCD
TRISCbits.RC0 = 0; //Set it output for RS
TRISCbits.RC1 = 0; //Set it output for RW
TRISCbits.RC2 = 0; //Set it output for en
TRISCbits.RC7 = 1; //RX pin set as input
SPBRG=spbrg_value; //Fill SPBRG register to set the baud rate
RCSTAbits.SPEN=1; // To activate serial port (Tx and Rx pins)
RCSTAbits.CREN=1; // To enable continuous reception
while(1)
{
unsigned char ch;
unsigned char utc[10]= {0};
unsigned char lat[9]= {0};
char NS,EW;
unsigned char longt[10]= {0};
int i,j,k;
again:
lcd_ini(); //initialize the LCD
ch= rx_data();
if (ch=='$')
{
ch= rx_data();
if (ch=='G')
{
ch= rx_data();
if (ch=='P')
{
ch= rx_data();
if (ch=='G')
{
ch= rx_data();
if (ch=='G')
{
ch= rx_data();
if (ch=='A')
{
ch=rx_data();
if (ch==',')
{
for(i=1;i<11;i++)
{
utc[i]=rx_data();
}
rx_data();// , get the caracter ',' but it just to get the caracter. Just to separate utc[10] and lat[9]
for(j=1;j<10;j++)
{
lat[j]=rx_data();
}
rx_data(); // , get the caracter ',' but it just to get the caracter. Just to separate lat[9] and NS
NS=rx_data(); // is it North or South
rx_data(); // , get the caracter ',' but it just to get the caracter. Just to separate NS and longt[10]
for(k=1;k<11;k++)
{
longt[k]=rx_data();
}
rx_data(); // ,
EW=rx_data();//is it east or west
}
} else goto again;
} else goto again;
} else goto again;
}
}
}
//display Latitude & Longitude
lcdcmd(0x80);
for(j=1;j<10;j++)
{
lcddata(lat[j]);
}
lcddata(',');
lcddata(NS);
lcdcmd(0xC0);
for(k=1;k<11;k++)
{
lcddata(longt[k]);
}
lcddata(',');
lcddata(EW);
Delay10KTCYx( 250); // some delay (1000ms)
Delay10KTCYx( 250);
lcdcmd(0x01); //CLEAR DISPLAY AND DDRAM CONTENT
Delay10KTCYx( 250);
}
}- this is when the code start running
- DSC_0415 (640x360).jpg (183.97 KiB) Viewed 427 times
- this is when the code is repeating
- DSC_0416 (640x360).jpg (184.43 KiB) Viewed 427 times
