Gps.encode(); never returning true

Using Arduino Sensors
1

Hi! I've recently been trying to use a gps component with the tinygps library. I tried to use its examples, but I have found that the conditional gps.encode() never returns true. I keep the gps outside in an open area, and it used to work with the Adafruit gps library. I am using the ultimate breakout v3 GPS, and I have my RX pin connected to 7 and my TX pin to 8. How can I fix this?

This is my full sketch(the simple_test example with a few changes):

#include <SoftwareSerial.h>

#include <TinyGPS.h>

/* This sample code demonstrates the normal use of a TinyGPS object.
   It requires the use of SoftwareSerial, and assumes that you have a
   4800-baud serial GPS device hooked up on pins 4(rx) and 3(tx).
*/

TinyGPS gps;
SoftwareSerial ss(8, 7);

void setup()
{
  Serial.begin(115200);
  ss.begin(4800);
  
  Serial.print("Simple TinyGPS library v. "); Serial.println(TinyGPS::library_version());
  Serial.println("by Mikal Hart");
  Serial.println();
}

void loop()
{
  bool newData = false;
  unsigned long chars;
  unsigned short sentences, failed;

  // For one second we parse GPS data and report some key values
  for (unsigned long start = millis(); millis() - start < 1000;)
  {
    while (ss.available())
    {
      char c = ss.read();
      // Serial.write(c); // uncomment this line if you want to see the GPS data flowing
      if (gps.encode(c)) // Did a new valid sentence come in?
        newData = true;
    }
  }

  //if (newData)
  //{
    
    float flat, flon;
    unsigned long age;
    gps.f_get_position(&flat, &flon, &age);
    Serial.print("LAT=");
    Serial.print(flat == TinyGPS::GPS_INVALID_F_ANGLE ? 0.0 : flat, 6);
    Serial.print(" LON=");
    Serial.print(flon == TinyGPS::GPS_INVALID_F_ANGLE ? 0.0 : flon, 6);
    Serial.print(" SAT=");
    Serial.print(gps.satellites() == TinyGPS::GPS_INVALID_SATELLITES ? 0 : gps.satellites());
    Serial.print(" PREC=");
    Serial.print(gps.hdop() == TinyGPS::GPS_INVALID_HDOP ? 0 : gps.hdop());
 // }
  
  gps.stats(&chars, &sentences, &failed);
  Serial.print(" CHARS=");
  Serial.print(chars);
  Serial.print(" SENTENCES=");
  Serial.print(sentences);
  Serial.print(" CSUM ERR=");
  Serial.print(failed);
  Serial.print(" ");
  Serial.println(ss.available());
  char c = ss.read();
  Serial.print(" ");
  Serial.println(ss.encode(c));
  if (chars == 0)
    Serial.println("** No characters received from GPS: check wiring **");
}
2

Are you absolutely certain that this Baud rate is correct? Post a link to the product page for the GPS module.

  ss.begin(4800);

I have my RX pin connected to 7 and my TX pin to 8

Please explain what that means. The SoftwareSerial connections are defined the other way around in the line below:

SoftwareSerial ss(8, 7);

Test the GPS outdoors, just printing the raw NMEA data. If it does not have a satellite fix, that will be immediately obvious.

This echo program will do:

#include <SoftwareSerial.h>

SoftwareSerial mySerial(8, 7); //GPS (RX, TX) check correct pin assignments and baud rate

void setup() {
  mySerial.begin(9600); //CHECK
  Serial.begin(115200); 
  Serial.println("GPS start");
}

void loop() {
  while (mySerial.available()) {
    Serial.write(mySerial.read());
  }
}
3

This program returns this(after about a minute of printing):
(picture that I removed as to not reveal my location)

4

That looks good. Which Baud rate and connections are you now using?

5

I am using the ones used in your echo program(reading the serial at 115200).

6

Then you had the wrong Baud rate in your original program.

1 Like
7

I am testing it again with the correct one. By the way, should I remove the image of the gps data that I sent? Would it reveal any information?

8

The GPS data tells us your current location, to within a few meters.

1 Like
9

Ok. It works! Thanks a lot!

10

If gps.encode() returns false it means there are no valid NMEA sentences to read or the baud rate is wrong.

Even if the GPS is indoors, in a cave and has no antenna, it should still produce NMEA sentences, but there will be no fix data.

11

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