GPS, Adafruit ver 3.0, Serial Interface

GPS modules are great in that the moment you turn them on, they'll start spitting out data, and trying to get a 'fix' (location verification). Like pretty much every GPS in existence, the Adafruit Ultimate GPS uses TTL serial output to send data so the best way to first test the GPS is to wire it directly to the computer via the TTL serial to USB converter on an Arduino. You can also use an FTDI Friend or other TTL adapter but for this demonstration we'll use a classic Arduino.

Quick Spec

• 165 dBm sensitivity, 10 Hz updates, 66 channels
• 5V friendly design and only 20mA current draw
• Breadboard friendly + two mounting holes
• RTC battery-compatible
• Built-in datalogging
• PPS output on fix
• 25Km altitude
• Internal patch antenna + u.FL connector for external active antenna
• Fix status LED

Resources

• Adafruit GPS Library
• Tutorial from Adafruit
• Download tutorial in Pdf
• Mini GPS tool (windows only)
• Utilities and more downloads

Code Example

#include "Wire.h"
#include "SD.h"
#include "SoftwareSerial.h"
#include "TinyGPS.h"
#include "RTClib.h"

const int chipSelect = 10;
RTC_Millis RTC;
File dataFile;

TinyGPS gps;
SoftwareSerial ss(3, 4);

void setup() 
{
  Serial.begin(115200);
  Serial.print("Initializing SD card...");
  ss.begin(9600);
  pinMode(chipSelect, OUTPUT);
  RTC.adjust(DateTime(__DATE__, __TIME__));
 
  // see if the card is present and can be initialized:
  if (!SD.begin(chipSelect)) {
    Serial.println("Card failed, or not present");
    // don't do anything more:
    while (1) ;
  }
  Serial.println("card initialized.");
 
  // Open up the file we're going to log to!
  dataFile = SD.open("GPStest.txt", FILE_WRITE);
  if (! dataFile) {
    Serial.println("error opening GPStest.txt");
    // Wait forever since we cant write data
    while (1) ;
  } 
}

void loop()                  
{
  DateTime now = RTC.now();
  bool newData = false;

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;
    int year;
    byte month, day, hour, minute, second, hundredths;
    gps.f_get_position(&flat, &flon, &age);
    gps.crack_datetime(&year, &month, &day, &hour, &minute, &second, &hundredths, &age);
        char sz[32];
    sprintf(sz, "%02d/%02d/%02d, %02d:%02d:%02d,  ",
     month, day, year, hour, minute, second);
   
    Serial.print("");
    Serial.print(flon == TinyGPS::GPS_INVALID_F_ANGLE ? 0.0 : flon, 6);
    Serial.print(", ");
    Serial.print(flat == TinyGPS::GPS_INVALID_F_ANGLE ? 0.0 : flat, 6);
    Serial.print(", ");
    Serial.println(now.unixtime());

    dataFile.print("");
    dataFile.print(flon == TinyGPS::GPS_INVALID_F_ANGLE ? 0.0 : flon, 6);
    dataFile.print(", ");
    dataFile.print(flat == TinyGPS::GPS_INVALID_F_ANGLE ? 0.0 : flat, 6);
    dataFile.print(", ");
    dataFile.println(now.unixtime());
  }

  dataFile.flush();
  delay(500);
}

Shipping List

• 1 x GPS, Adafruit ver 3.0, Serial Interface