Vehicle Tracking System Problem

[jayanth.devarayanadurga]

I am doing a Vehicle Tracking System. My GPS works baudrate 4800 bps. I am using PIC18F46K22 at 20 MHz. I am just testing the receiving of GPS data. If I use ring buffer then it doesn't work. If I use just an ordinary buffer then I don'r get all the data. I am testing by echoing the data back to UART and watching the echo on PC. My GPS data frequency is 1 Hz. Please tell me how to receive GPS data properly and display it on PC?


If my ISR contains the below code it doesn't work but if I don't use ring buffer then it echos some part of the data.

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Code C - [expand]
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void Interrupt() {
          if(RC1IF_bit){
 
                 if(i > MAXBUFFSIZE)i = 0;
                 gpsData[i++] = RCREG1;
                 gpsData[i] = '\0';
 
          }
 
 
}

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[anishpsla]

Hope this will work. It's a Raspberry pi based code. But easy to port into MikroC .

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Code C - [expand]
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*
 *  Description: This skecth gets the GPS coordinates and sends it 
 *  through HTTP to a php script. For more information about the AT commands, 
 *  refer to the AT command manual.
 *
 *  Copyright (C) 2013 Libelium Comunicaciones Distribuidas S.L.
 *  [url]https://www.libelium.com[/url]
 *
 *  This program is free software: you can redistribute it and/or modify 
 *  it under the terms of the GNU General Public License as published by 
 *  the Free Software Foundation, either version 3 of the License, or 
 *  (at your option) any later version. 
 *  
 *  This program is distributed in the hope that it will be useful, 
 *  but WITHOUT ANY WARRANTY; without even the implied warranty of 
 *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the 
 *  GNU General Public License for more details. 
 *  
 *  You should have received a copy of the GNU General Public License 
 *  along with this program.  If not, see <http://www.gnu.org/licenses/>. 
 *
 *  Version 0.1
 *  Author: Alejandro Gallego 
 */
 
 
int8_t answer;
int onModulePin= 2;
 
char data[100];
int data_size;
 
char aux_str[30];
char aux;
int x = 0;
char N_S,W_E;
 
char url[] = "your ip address or your domain";
char frame[200];
 
char latitude[15];
char longitude[15];
char altitude[6];
char date[16];
char time[7];
char satellites[3];
char speedOTG[10];
char course[10];
 
 
void setup(){
 
    pinMode(onModulePin, OUTPUT);
    Serial.begin(115200);   
 
    Serial.println("Starting...");
    power_on();
 
    delay(3000);
 
    // sets the PIN code
    sendATcommand("AT+CPIN=****", "OK", 2000);
 
    delay(3000);
    
    // starts the GPS and waits for signal
    while ( start_GPS() == 0);  //Not used
    
    // registration status on GSM NW
    while (sendATcommand("AT+CREG?", "+CREG: 0,1", 2000) == 0);
 
    // sets APN , user name and password
    sendATcommand("AT+SAPBR=3,1,\"Contype\",\"GPRS\"", "OK", 2000);
    sendATcommand("AT+SAPBR=3,1,\"APN\",\"apn\"", "OK", 2000);
    sendATcommand("AT+SAPBR=3,1,\"USER\",\"user_name\"", "OK", 2000);
    sendATcommand("AT+SAPBR=3,1,\"PWD\",\"password\"", "OK", 2000);
 
    // gets the GPRS bearer
    while (sendATcommand("AT+SAPBR=1,1", "OK", 20000) == 0)
    {
        delay(5000);
    }
 
}
 
void loop(){
 
    // gets GPS data
    get_GPS();
    
    // sends GPS data to the script
    send_HTTP();
 
    delay(5000);
 
}
 
void power_on(){
 
    uint8_t answer=0;
 
    // checks if the module is started
    answer = sendATcommand("AT", "OK", 2000);
    if (answer == 0)
    {
        // power on pulse
        digitalWrite(onModulePin,HIGH);
        delay(3000);
        digitalWrite(onModulePin,LOW);
 
        // waits for an answer from the module
        while(answer == 0){  
            // Send AT every two seconds and wait for the answer   
            answer = sendATcommand("AT", "OK", 2000);    
        }
    }
 
}
 
int8_t start_GPS(){
 
    unsigned long previous;
 
    previous = millis();
    // starts the GPS
    sendATcommand("AT+CGPSPWR=1", "OK", 2000);
    sendATcommand("AT+CGPSRST=0", "OK", 2000);
 
    // waits for fix GPS
    while(( (sendATcommand("AT+CGPSSTATUS?", "2D Fix", 5000) || 
        sendATcommand("AT+CGPSSTATUS?", "3D Fix", 5000)) == 0 ) && 
        ((millis() - previous) < 90000));
 
    if ((millis() - previous) < 90000)
    {
        return 1;
    }
    else
    {
        return 0;    
    }
}
 
int8_t get_GPS(){
 
    int8_t counter, answer;
    long previous;
 
    // First get the NMEA string
    // Clean the input buffer
    while( Serial.available() > 0) Serial.read(); 
    // request Basic string
    sendATcommand("AT+CGPSINF=0", "AT+CGPSINF=0\r\n\r\n", 2000);
 
    counter = 0;
    answer = 0;
    memset(frame, '\0', 100);    // Initialize the string
    previous = millis();
    // this loop waits for the NMEA string
    do{
 
        if(Serial.available() != 0){    
            frame[counter] = Serial.read();
            counter++;
            // check if the desired answer is in the response of the module
            if (strstr(frame, "OK") != NULL)    
            {
                answer = 1;
            }
        }
        // Waits for the asnwer with time out
    }
    while((answer == 0) && ((millis() - previous) < 2000));  
 
    frame[counter-3] = '\0'; 
    
    // Parses the string 
    strtok(frame, ",");
    strcpy(longitude,strtok(NULL, ",")); // Gets longitude
    strcpy(latitude,strtok(NULL, ",")); // Gets latitude
    strcpy(altitude,strtok(NULL, ".")); // Gets altitude 
    strtok(NULL, ",");    
    strcpy(date,strtok(NULL, ".")); // Gets date
    strtok(NULL, ",");
    strtok(NULL, ",");  
    strcpy(satellites,strtok(NULL, ",")); // Gets satellites
    strcpy(speedOTG,strtok(NULL, ",")); // Gets speed over ground. Unit is knots.
    strcpy(course,strtok(NULL, "\r")); // Gets course
 
    convert2Degrees(latitude);
    convert2Degrees(longitude);
    
    return answer;
}
 
/* convert2Degrees ( input ) - performs the conversion from input 
 * parameters in  DD°MM.mmm’ notation to DD.dddddd° notation. 
 * 
 * Sign '+' is set for positive latitudes/longitudes (North, East)
 * Sign '-' is set for negative latitudes/longitudes (South, West)
 *  
 */
int8_t convert2Degrees(char* input){
 
    float deg;
    float minutes;
    boolean neg = false;    
 
    //auxiliar variable
    char aux[10];
 
    if (input[0] == '-')
    {
        neg = true;
        strcpy(aux, strtok(input+1, "."));
 
    }
    else
    {
        strcpy(aux, strtok(input, "."));
    }
 
    // convert string to integer and add it to final float variable
    deg = atof(aux);
 
    strcpy(aux, strtok(NULL, '\0'));
    minutes=atof(aux);
    minutes/=1000000;
    if (deg < 100)
    {
        minutes += deg;
        deg = 0;
    }
    else
    {
        minutes += int(deg) % 100;
        deg = int(deg) / 100;    
    }
 
    // add minutes to degrees 
    deg=deg+minutes/60;
 
 
    if (neg == true)
    {
        deg*=-1.0;
    }
 
    neg = false;
 
    if( deg < 0 ){
        neg = true;
        deg*=-1;
    }
    
    float numeroFloat=deg; 
    int parteEntera[10];
    int cifra; 
    long numero=(long)numeroFloat;  
    int size=0;
    
    while(1){
        size=size+1;
        cifra=numero%10;
        numero=numero/10;
        parteEntera[size-1]=cifra; 
        if (numero==0){
            break;
        }
    }
   
    int indice=0;
    if( neg ){
        indice++;
        input[0]='-';
    }
    for (int i=size-1; i >= 0; i--)
    {
        input[indice]=parteEntera[i]+'0'; 
        indice++;
    }
 
    input[indice]='.';
    indice++;
 
    numeroFloat=(numeroFloat-(int)numeroFloat);
    for (int i=1; i<=6 ; i++)
    {
        numeroFloat=numeroFloat*10;
        cifra= (long)numeroFloat;          
        numeroFloat=numeroFloat-cifra;
        input[indice]=char(cifra)+48;
        indice++;
    }
    input[indice]='\0';
 
 
}
 
void send_HTTP(){
    
    // Initializes HTTP service
    answer = sendATcommand("AT+HTTPINIT", "OK", 10000);
    if (answer == 1)
    {
        // Sets CID parameter
        answer = sendATcommand("AT+HTTPPARA=\"CID\",1", "OK", 5000);
        if (answer == 1)
        {
            // Sets url 
            sprintf(aux_str, "AT+HTTPPARA=\"URL\",\"http://%s/demo_sim908.php?", url);
            Serial.print(aux_str);
            sprintf(frame, "visor=false&latitude=%s&longitude=%s&altitude=%s&time=%s&satellites=%s&speedOTG=%s&course=%s",
            latitude, longitude, altitude, date, satellites, speedOTG, course);
            Serial.print(frame);
            answer = sendATcommand("\"", "OK", 5000);
            if (answer == 1)
            {
                // Starts GET action
                answer = sendATcommand("AT+HTTPACTION=0", "+HTTPACTION:0,200", 30000);
                if (answer == 1)
                {
 
                    Serial.println(F("Done!"));
                }
                else
                {
                    Serial.println(F("Error getting url"));
                }
 
            }
            else
            {
                Serial.println(F("Error setting the url"));
            }
        }
        else
        {
            Serial.println(F("Error setting the CID"));
        }    
    }
    else
    {
        Serial.println(F("Error initializating"));
    }
 
    sendATcommand("AT+HTTPTERM", "OK", 5000);
    
}
 
 
int8_t sendATcommand(char* ATcommand, char* expected_answer1, unsigned int timeout){
 
    uint8_t x=0,  answer=0;
    char response[100];
    unsigned long previous;
 
    memset(response, '\0', 100);    // Initialize the string
 
    delay(100);
 
    while( Serial.available() > 0) Serial.read();    // Clean the input buffer
 
    Serial.println(ATcommand);    // Send the AT command 
 
 
        x = 0;
    previous = millis();
 
    // this loop waits for the answer
    do{
        if(Serial.available() != 0){    
            response[x] = Serial.read();
            x++;
            // check if the desired answer is in the response of the module
            if (strstr(response, expected_answer1) != NULL)    
            {
                answer = 1;
            }
        }
        // Waits for the asnwer with time out
    }
    while((answer == 0) && ((millis() - previous) < timeout));    
 
    return answer;
}

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[jayanth.devarayanadurga]

I am attaching my mikroC Code. There is a string gpsData2 for testing. If it is used in the while(1) loop then I get the parsed data on Serial Terminal. The problem I am facing is if I use gpsData for parsing I don't get anything on the Serial Terminal. What might be the problem. My GPS module give data at 1 Hz. So, I have 1 sec time between receiving gps data and echoing it back to UART. The echoing is not working. I am echoing just for testing to see that all the GPS data is received serially. Please give some advice.