Adafruit Ultimate GPS Logger Sheild.

I am so tired of trying to figure out what is wrong. After countless cups of coffee and not knowing, I've decided to post here.
Hello All,

I have this GPS Sheild. (Overview | Adafruit Ultimate GPS Logger Shield | Adafruit Learning System)

Attached to an Arduino Uno R3.

When I upload and run this code on my board with the shield attached with the switch to 'Direct' I get Raw data and works fine.
void setup() {}
void loop() {}

But when I try to run the code they have to parse the data in order to get in all neat and print it out. It doesn't work. Even after changing to SoftwareSerial mySerial(8, 7);. All its printing out is TOP_SÎÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿ¨©Ò??¤DÃ\Füÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿ

I tried writing my own code to parse it, and ran into some issues there, but a different topic for a different day. I just feel like the code provided by adafruit for its product should work. I hope i'm not asking a lot. I posted something on this earlier. All i got was a sassy reply. Hope this time its more helpful.

Post your code. It looks like you are reading data when there is none to read.

Hey, so I got it to work. It works and gives me that data from the

This is what the code looks like:

// Test code for Adafruit GPS modules using MTK3329/MTK3339 driver
// This code shows how to listen to the GPS module in an interrupt
// which allows the program to have more 'freedom' - just parse
// when a new NMEA sentence is available! Then access data when
// desired.
// Tested and works great with the Adafruit Ultimate GPS module
// using MTK33x9 chipset
//    ------>
// Pick one up today at the Adafruit electronics shop 
// and help support open source hardware & software! -ada

#include <Adafruit_GPS.h>
#include <SoftwareSerial.h>

// If you're using a GPS module:
// Connect the GPS Power pin to 5V
// Connect the GPS Ground pin to ground
// If using software serial (sketch example default):
//   Connect the GPS TX (transmit) pin to Digital 3
//   Connect the GPS RX (receive) pin to Digital 2
// If using hardware serial (e.g. Arduino Mega):
//   Connect the GPS TX (transmit) pin to Arduino RX1, RX2 or RX3
//   Connect the GPS RX (receive) pin to matching TX1, TX2 or TX3

// If you're using the Adafruit GPS shield, change 
// SoftwareSerial mySerial(3, 2); -> SoftwareSerial mySerial(8, 7);
// and make sure the switch is set to SoftSerial

// If using software serial, keep these lines enabled
// (you can change the pin numbers to match your wiring):
SoftwareSerial mySerial(8, 7);

Adafruit_GPS GPS(&mySerial);
// If using hardware serial (e.g. Arduino Mega), comment
// out the above six lines and enable this line instead:
//Adafruit_GPS GPS(&Serial1);

// Set GPSECHO to 'false' to turn off echoing the GPS data to the Serial console
// Set to 'true' if you want to debug and listen to the raw GPS sentences. THIS IS SET TO FALSE TO REMOVE THE RAW DATA
#define GPSECHO  false

// this keeps track of whether we're using the interrupt
// off by default!
boolean usingInterrupt = false;
void useInterrupt(boolean); // Func prototype keeps Arduino 0023 happy

void setup()  
  // connect at 115200 so we can read the GPS fast enough and echo without dropping chars
  // also spit it out
  Serial.println("Adafruit GPS library basic test!");

  // 9600 NMEA is the default baud rate for Adafruit MTK GPS's- some use 4800
  // uncomment this line to turn on RMC (recommended minimum) and GGA (fix data) including altitude
  // uncomment this line to turn on only the "minimum recommended" data
  // For parsing data, we don't suggest using anything but either RMC only or RMC+GGA since
  // the parser doesn't care about other sentences at this time
  // Set the update rate
  GPS.sendCommand(PMTK_SET_NMEA_UPDATE_1HZ);   // 1 Hz update rate
  // For the parsing code to work nicely and have time to sort thru the data, and
  // print it out we don't suggest using anything higher than 1 Hz

  // Request updates on antenna status, comment out to keep quiet

  // the nice thing about this code is you can have a timer0 interrupt go off
  // every 1 millisecond, and read data from the GPS for you. that makes the
  // loop code a heck of a lot easier!

  // Ask for firmware version

// Interrupt is called once a millisecond, looks for any new GPS data, and stores it
  char c =;
  // if you want to debug, this is a good time to do it!
#ifdef UDR0
  if (GPSECHO)
    if (c) UDR0 = c;  
    // writing direct to UDR0 is much much faster than Serial.print 
    // but only one character can be written at a time. 

void useInterrupt(boolean v) {
  if (v) {
    // Timer0 is already used for millis() - we'll just interrupt somewhere
    // in the middle and call the "Compare A" function above
    OCR0A = 0xAF;
    TIMSK0 |= _BV(OCIE0A);
    usingInterrupt = true;
  } else {
    // do not call the interrupt function COMPA anymore
    TIMSK0 &= ~_BV(OCIE0A);
    usingInterrupt = false;

uint32_t timer = millis();
void loop()                     // run over and over again
  // in case you are not using the interrupt above, you'll
  // need to 'hand query' the GPS, not suggested :(
  if (! usingInterrupt) {
    // read data from the GPS in the 'main loop'
    char c =;
    // if you want to debug, this is a good time to do it!
    if (GPSECHO)
      if (c) Serial.print(c);
  // if a sentence is received, we can check the checksum, parse it...
  if (GPS.newNMEAreceived()) {
    // a tricky thing here is if we print the NMEA sentence, or data
    // we end up not listening and catching other sentences! 
    // so be very wary if using OUTPUT_ALLDATA and trytng to print out data
    //Serial.println(GPS.lastNMEA());   // this also sets the newNMEAreceived() flag to false
    if (!GPS.parse(GPS.lastNMEA()))   // this also sets the newNMEAreceived() flag to false
      return;  // we can fail to parse a sentence in which case we should just wait for another

  // if millis() or timer wraps around, we'll just reset it
  if (timer > millis())  timer = millis();

  // approximately every 2 seconds or so, print out the current stats
  if (millis() - timer > 2000) { 
    timer = millis(); // reset the timer
    Serial.print("\nTime: ");
    Serial.print(GPS.hour, DEC); Serial.print(':');
    Serial.print(GPS.minute, DEC); Serial.print(':');
    Serial.print(GPS.seconds, DEC); Serial.print('.');
    Serial.print("Date: ");
    Serial.print(, DEC); Serial.print('/');
    Serial.print(GPS.month, DEC); Serial.print("/20");
    Serial.println(GPS.year, DEC);
    Serial.print("Fix: "); Serial.print((int)GPS.fix);
    Serial.print(" quality: "); Serial.println((int)GPS.fixquality); 
    if (GPS.fix) {
      Serial.print("Location: ");
      Serial.print(GPS.latitude, 4); Serial.print(;
      Serial.print(", "); 
      Serial.print(GPS.longitude, 4); Serial.println(GPS.lon);
      Serial.print("Speed (knots): "); Serial.println(GPS.speed);
      Serial.print("Angle: "); Serial.println(GPS.angle);
      Serial.print("Altitude: "); Serial.println(GPS.altitude);
      Serial.print("Satellites: "); Serial.println((int)GPS.satellites);

I'm seeking some straightforward answers if possible. What would I have to do, to only get the speed and transmit it through the Xbee wifi sheild. And all the other data just being logged onto the SD card. :sweat_smile: :roll_eyes:

So after a lot of cups of coffee, I figured it out. I'm successfully sending BMS data through CAN shield and GPS data through GPS shield all connected to an Uno wirelessly using a X-Bee WiFi module to another Uno connected a computer. Yay!!

What I would like to know:

can a GPS shield log and transmit data simultaneously, and i have no background in lab-view. And i want to use lab-view to display my real time data. Can you guys point me to a direction where I can make that happen? Viewing real time data in labview. Especially, the speed and bms values.

And the bms values received are in ascii hex. is there a way to convert them in lab view to values I can understand.

Help will be greatly appreciated!

Why isn't anyone helping? =( =( =( =(

No they can not do both simultaneously. Oh, and here is an other library, TinyGPS++ | Arduiniana, and tutorial, Finding Your Way with GPS - Make:, for that GPS. It can perform more advanced functions but is easier to use.

Yo how did you solve initial problem? Im having same issue. Works when i upload empty sketch but then when i upload the parsing sketch change sketch to 8,7 and everything i just get question marks on the serial monster. I believe the issue is that my gps isn't finding a fix but I waited like 45mins and then just gave up. How did you fix yours. For anyone else that has questions for me Im following the steps for the gps logger shield on the adafruit website

Try NeoGPS and NeoSWSerial:

#include <NMEAGPS.h>

NMEAGPS  gps; // This parses the GPS characters
gps_fix  fix; // This holds on to the latest values

//   BEST: For a Mega, Leonardo or Due, use the extra hardware serial port
//#define gpsPort Serial1

//   2nd BEST:  For other devices, use AltSoftSerial on the required pins 
//                 (8&9 for an UNO)
// #include <AltSoftSerial.h>
// AltSoftSerial gpsPort;

//   3rd BEST:  If you can't use those specific pins (are you sure?), 
//                 use NeoSWSerial on any two pins @ 9600, 19200 or 38400
#include <NeoSWSerial.h>
NeoSWSerial gpsPort( 8, 7 ); // Arduino RX pin (to GPS TX pin), Arduino TX pin (to GPS RX pin)

//   WORST:  SoftwareSerial is NOT RECOMMENDED


void setup()
  while (!Serial)
  Serial.print( F("NMEAsimple.INO: started\n") );



void loop()
  while (gps.available( gpsPort )) {
    fix =;

    Serial.print( F("Location: ") );
    if (fix.valid.location)
      Serial.print( fix.latitude(), 6 ); // floating-point display
    Serial.print( ',' );
    if (fix.valid.location)
      Serial.print( fix.longitude(), 6 ); // floating-point display

    Serial.print( F(", Altitude: ") );
    if (fix.valid.altitude)
      Serial.print( fix.altitude() );


The above sketch is really the NeoGPS example NMEAsimple.ino.

Make sure the GPS TX pin is connected to Arduino pin 8 (the NeoSWSerial receiving pin), and the GPS RX pin is connected to Arduino pin 7 (the NeoSWSerial transmitting pin). The silkscreen on the shield is misleading...

It would be even better to use pins 8 & 9 with AltSoftSerial, but you would have to cut the traces to the "Soft Serial/Direct" switch. Then solder or jumper a wire from GPS TX to Arduino 8, and GPS RX to Arduino 9. SoftwareSerial is very inefficient, because it disables interrupts for long periods of time. This will interfere with other parts of your sketch.

If you want to try it, NeoGPS is available from the Arduino IDE Library Manager, under the menu Sketch -> Include Library -> Manage Libraries. NeoSWSerial from the link above.


Thanks! NeoSWSerial is not showing up though when i search for it