I am trying to get GPS data from my GY-NEO6MV2, but the results are not readable with SoftwareSerial or other libraries. I have used the following code that has worked for others on the net, but I don't get any results from it. The GPS data appears perfectly in the serial monitor, but the interfaces such as SoftwareSerial fail to receive it. Instead, I receive a bunch of -1s. Here is the code:
#include "SoftwareSerial.h"
// Constants
#define txPin 1 //tx pin in GPS connection
#define rxPin 2 //rx pin in GPS connection
// Set up the GPS serial port
SoftwareSerial gps = SoftwareSerial(rxPin, txPin);
// Variables
byte byteGPS = 0;
int i = 0;
int state = 0;
char dataGPG[100] = "";
char *pch;
char *GGA[15];
int sat = 0;
void setup() {
//setup for Serial Port
Serial.begin(9600);
Serial.flush();
//setup for GPS Serial Port
pinMode(rxPin, INPUT);
pinMode(txPin, OUTPUT);
gps.begin(4800);
gps.flush();
//setup satellites signal
pinMode(13, OUTPUT);
digitalWrite(13, LOW);
// Turn off the led until a satellite signal
}
void loop() {
gps.flush();
Serial.flush();
Serial.println("Waiting GPS data...");
// Prepare all for reading GPS Serial Port
memset(dataGPG, 0, sizeof(dataGPG)); // Remove previous readings
byteGPS = 0; // Remove data
byteGPS = gps.read(); // Read the byte that is in the GPS serial port
delay(1000);
// Find the desired string
while (byteGPS != '$') {
byteGPS = gps.read();
/******* Here I just get -1 *************/
}
// Save the string in an array
i = 1;
dataGPG[0] = '$';
while (byteGPS != '*' ) {
byteGPS = gps.read();
dataGPG[i] = byteGPS;
i++;
}
dataGPG[i] = '\0';
string(); // Call to the function that manipulates our string
}
/*
This function will allow us to identify the data we need to get the longitude, latitude ...
*/
void string() {
i = 0;
memset(GGA, 0, sizeof(GGA)); // Remove previous readings
pch = strtok (dataGPG, ",");
// Analyze the saved interval in pch to see if it the needed string
if (strcmp(pch, "$GPGGA") == 0) {
while (pch != NULL) {
pch = strtok (NULL, ",");
GGA[i] = pch;
i++;
}
plot(GGA, "$GPGGA");
// Call to the function that is going to display the data
}
}
/*
This function organize the gps data received for printing in the serial monitor.
*/
void plot(char **GGAPrint, char *trama) {
state = atoi(GGAPrint[5]);
sat = atoi(GGAPrint[6]);
if (trama == "$GPGGA" && state == 1) {
digitalWrite(13, HIGH);
// Then there are satellites, the LED switch ON
Serial.println("");
Serial.println("----------------------------------------------");
Serial.print("UTC Hour -> ");
Serial.println(GGAPrint[0]);
Serial.print("Latitude -> ");
Serial.print(GGAPrint[1]);
Serial.println(GGAPrint[2]);
Serial.print("Longitude -> ");
Serial.print(GGAPrint[3]);
Serial.println(GGAPrint[4]);
Serial.print("GPS quality: 0=null; 1=GPS fixed -> ");
Serial.println(GGAPrint[5]);
Serial.print("Number of satellites -> ");
Serial.println(sat);
Serial.print("Horizontal Dilution of Precision -> ");
Serial.println(GGAPrint[7]);
Serial.print("Antenna altitude -> ");
Serial.print(GGAPrint[8]);
Serial.println(GGAPrint[9]);
Serial.print("Geoid Separation -> ");
Serial.print(GGAPrint[10]);
Serial.println(GGAPrint[11]);
Serial.println("----------------------------------------------");
Serial.println("");
} else {
// If no satellite connection
digitalWrite(13, LOW); // Turn off the LED
Serial.println("");
Serial.println("-----------------------------");
Serial.print("|--- Satellites Used -->");
Serial.print(sat);
Serial.println(" |");
Serial.println("|----Waiting location----|");
Serial.println("-----------------------------");
Serial.println("");
}
}
The result wasn't correct and I only saw this sentence:
Waiting GPS data...
I updated the code by adding gps.available() and delay(2) before every gps.read() and it worked. I still don't know why, but this worked:
#include "SoftwareSerial.h"
// Constants
#define txPin 2 //tx pin in GPS connection
#define rxPin 3 //rx pin in GPS connection
char gps_data[200];
SoftwareSerial gps = SoftwareSerial(rxPin, txPin);
char byteGPS = 0;
void setup() {
Serial.begin(9600);
pinMode(rxPin, INPUT);
pinMode(txPin, OUTPUT);
gps.begin(9600);
}
void loop() {
byteGPS = '0'; // Remove data
memset(gps_data, '\0', 200);
while (gps.available())
{
while (gps.available())
{
byteGPS = gps.read(); // Read the char that is in the GPS serial port
if (byteGPS == '$') break;
}
int i=0;
while (gps.available()) // Available3
{
delay(1);
gps_data[i++] = byteGPS;
byteGPS = gps.read();
if ((byteGPS == '\n')) break;
}
if (i > 1)
{
delay(1);
parse_gps_data();
}
}
}
The code in parse_gps_data() parses the data from gps. It works fine.
gps.flush(). If you clear the input buffer that is receiving the GPS data every second or so its possible you will loose data.