Hi Mikal. I’m using a GPS simulator that outputs GGA strings. The fix in the GGA sentence is 1. But gps.encode just returns 0… Do i nid RMC strings for it to work too? All i wanted was to retrieve the lat/lon frm the GGA.

Thnx for the reply Mikal. Here u go.

$GPGGA,090000.00,0117.81300741,N,10348.09117993,E,1,05,2.87,160.00,M,-21.3213,M,,*7B
$GPGGA,090000.05,0117.81300741,N,10348.09117993,E,1,05,2.87,160.00,M,-21.3213,M,,*7E
$GPGGA,090000.10,0117.81300741,N,10348.09117993,E,1,05,2.87,160.00,M,-21.3213,M,,*7A
$GPGGA,090000.15,0117.81300741,N,10348.09117993,E,1,05,2.87,160.00,M,-21.3213,M,,*7F
$GPGGA,090000.20,0117.81300741,N,10348.09117993,E,1,05,2.87,160.00,M,-21.3213,M,,*79
$GPGGA,090000.25,0117.81300741,N,10348.09117993,E,1,05,2.87,160.00,M,-21.3213,M,,*7C
$GPGGA,090000.30,0117.81300741,N,10348.09117993,E,1,05,2.87,160.00,M,-21.3213,M,,*78

I’ve pasted the first 2 lines above into the GGA string in the static test. Checksum seems fine and flat/flon was returned quite accurately. Hw’d i knw if there’s CR or LF at the end of each sentence? Thnx again!

i’m usin a copy of Free SatGen NMEA software from: http://www.labsat.co.uk
output frm the software is then passed thru a FTDI breakout board to the arduino.

so i’m supposed to add the line “bool success = gps.encode(‘\r’);” into the data simulated?

THANKS for the help!!

why my arduino ide uno cannot receive any data from gps when serialmonitor . but i can get data when using mini gps . ?

Hi, am using a GPS shield with the arduino uno. I uploaded the code above but all I get is strange characters in my serial monitor. what could be the reason?

Hi ,
I am using this with the mediatek v12 from diydrones.
I have managed to get the baud and pins right and I am getting data in serial when running, test_with_gps_device.
My problem is that I am getting a checksum fail on every new line of data,

this is a typical line from the serial
5 138 42.89535 -8.52799 873 00/00/2000 19:26:23 879 315.80 ****** ***** *** 1147 30.51 NNE 4568 31 32

I am inside with poor coverage, but this doesnt change when outside, I also have no date returned, although the time is correct.

Do you have any idea what is going on ?
thanks for the ace library

Hey Mikal, I really love your library! I have a question about it, however. It usually takes about 1 second to actually encode the data coming from the GPS. This is, unfortunately, much too long for my needs. I need to be able to receive at least 5 GPS points per second, preferably more. The code I’m using is simple enough, so I’m not really sure where it’s hanging up. Any help would be greatly appreciated. I am using an Arduino Mega2560 with a Seeedstudio uBlox GPS Bee connected on Serial1 at a baud rate of 9600.

void loop()
{
while(Serial1.available())
{
if(gps.encode(Serial1.read()))
{
getCurrentPoint(gps);
}
}
}

void getCurrentPoint(TinyGPS &gps)
{
gps.f_get_position(&lat, &lon);
gps.get_datetime(&date, &time, &age);
}

Mikal, I am new to Arduino and programming in general. I am having great difficulty using TinyGPS. I am able to connect my GPS to my Arduino and get NEMA sentences to display on my IDE Serial Monitor using my own basic code. However, I have been unsuccessful at parsing the information using TinyGPS. Can you, or anyone here, provide a full sample code for displaying the basics (position, date, time, altitude, speed and course)? My goal is to output this info to an LCD.

Oh wow, I can’t believe I never considered that as an option. Thanks so much for your help!

Mikal, I am using a Ublox LEA-5M-0-002 but am getting a strange reading. I have included a sample of the NEMA sentences that I am seeing. I personally can’t determine what is going on but it does not seem correct at all. I may try another module as I have access to dozens. Any help would be appreciated.

$GPGGA,002552.00,4426.03219,N,09308.79763,W1,06,1.69,303.7,M,-31.0,M,,*6D
$GPRMC,002552.00,A,4426.03219,N,09308.79763,W,0.264,115.07,100713,,,A*79

Hi Mikal,
love your TinyGPS

I have it working on Maple and Flymaple now.
Only one change to your library is required to make it compatible with both Arduino and Maple:

In TinyGPS.cpp Add:

#include <stdlib.h>

before

#include "TinyGPS.h"

else get a compile error concerning atoi()

I have tested this change on both Maple and Arduino. It is necessary for Maple and innocuous for Arduino.

Can you add it to future release?

Cheers.

Thanks for sharing your library. It is feeding my enjoyment of learning to use various sensors.

I’m curious why I get different lat/long reads from the same $GPGGA sentences whether I am using your TinyGPS library or just the Arduino RX pin. Without your library, there is an offset of several miles from my true location. Though, the DOP’s and satellites accessed are the same (and date and time differ in only the seconds that it takes to upload the sketches). The altitude is fairly close, but at my desk in the SF Bay Area, the read varies from 10 meters under to 20 meters high, regardless of the sketch (possibly influenced by economic factors).

At least, I am getting consistent numbers from multiple fixes and do not think that the difference is in the serials. Rather, I think that the differences is in the offset values that the SKM53 does not transmit ($GPDTM).

Since the GPS module does not receive data from the Arduino, I am assuming that you are using a different correction for the values. Can you tell me what you are using? Is it a constant?

Thanks again for all of your work!!

Hi Mikal!
How can I check if the GPRMC reports a correct status “A” or incorrect “V”?. Thanks so much and Regards!

HI Mikal, There is protocol calls SiRF. What is the different between SiRF, UART, . could I use your library to send NMEA 0183 stranded commands via SiRF protocol. I will be glad to hear from you. Thank You Very Much.

Is this library compatible with all the gps modules/shields??

Hi,

I try to put the code in my Arduino, and get the GPS data, but this is actually what I get:

Ň`zI|1Aˆ

Is there any way to get latitude/longitude seconds precision to 2 decimal places via this library?
I’ve tried both gps.f_get_position and gps.get_position but both of them omit last digit. It basically returns coordinate like this: 41N 12′ 48.3″ instead of 41N 12′ 48.32″
In other words gps.get_position returns 7 digit number instead of 8 digit number for &lat, &lon…

Thanks! :)

Hi Mikal,

How can we add the GPRMB sentence to the library ?
I would like to use the L and R information for my rudder project.

Thanks,
Ben

@Mikal,
Hi, I am interested by tinyGPS++, where can we find it?
Thanks !

Hi Mikal, first of all thanks for the wonderful TinyGPS library.
I have one problem getting the altitude. It shows as 1000000. I am using the seeeduino stalker, with xbee GPS. I get the altitude and save in the SD card.
Below follows the code, anyone have some clue about what is happening?

float altitude_float = gps.f_altitude();

char altitude_char[25];
dtostrf(altitude_float,1,2,altitude_char);
String my_altitude_as_string = String(altitude_char);

Then I save “my_altitude_as_string” in my SD card.

I do the same for latitude and longitude, and the data is coming with no problem. Any hint would help.
Thank you!

Thank you for your response Mikal,

After some tests I could realize that the problem is in the NMEA that my GPS is creating.

Below follows one example of a NMEA generated (I do not have my arduino here to get more NMEA examples):

$GPVTG,,T,,M,0.064,N,0.1K581N9147,1098.AA451222476235.,,20$G,,$GPRMC,020231.00,A,4458.82317,N,09311.14624,W,0.034,,100913,,,D*65

I realized something weird. When I turn on the arduino with the GPS, in the first 30 seconds it shows $GPGGA, and after starting to get valid fixes, it does not show $GPGGA anymore, just a NMEA like the one above.

To get the NMEA above I used the code example you posted.

I also tested the same code with another seeeduino stalker and another GPS. But the same thing happened.

What is really weird is that once the NMEA was with the GPGGA rightly and after restarting the arduino I could not see it anymore. I got it just once, even after several tests. =(

Have you ever experienced something like this before?

Thank you!

Thank you for your fast response.
I changed my strategy and I am not using the SD card anymore. I got my arduino again and have just performed a new test:

I connected my GPS bee directly in the ports 2 and 3 of my arduino, and then I am using SoftwareSerial library. Then, I use the arduino serial to print in the serial monitor (I did this because my arduino uses the port 0 and 1 to connect in the xbee socket, and when I use the socket I cannot print in the Serial at the same time because they share the same ports).
Below follows my code:

#include
#include “TinyGPS.h”
TinyGPS gps;

#define RXPIN 2
#define TXPIN 3

SoftwareSerial nss(RXPIN, TXPIN);

void setup() {
Serial.begin(57600);
nss.begin(9600);
}

void loop()
{
unsigned short sentences = 0, failed = 0;
unsigned long chars = 0;

gps.stats(&chars, &sentences, &failed);

while (nss.available())
{
char input = nss.read();
Serial.print(input);
if (gps.encode(input))
{
float lat, lon;
unsigned long age;
gps.f_get_position(&lat, &lon, &age);

Serial.print(“\nLatitude.: “);
Serial.println(lat);
Serial.print(“Longitude: “);
Serial.println(lon);
Serial.print(“Altitude.: “);
Serial.println(gps.f_altitude());
Serial.print(“Satellites: “);
Serial.println(gps.satellites());
Serial.print(“Age……: “);
Serial.println(age);

Serial.print(“Chars….: “);
Serial.println(chars);
Serial.print(“Sentences: “);
Serial.println(sentences);
Serial.print(“Failed…: “);
Serial.println(failed);

}
}
}

And below is part of the content of the serial monitor. Note that after I get valid fixes, the NMEA changes and shows just $GPVTG and $GPRMC:

$GPVTG,,,,,,,,,N*30
$GPGGA,042115.00,,,,,0,00,99.9,,6
A,,,,,9999993
P,155,1,91,,,37$GV,02,*BGG,,410V
$GPRMC,042116.00,V,,,,,,,100913,,,N*77
$GPVTG,,,,,,,,,N*30
$GPGGA,042116.00,,,,,0,00,99.9,,*
SA,,,,,99999*
GV,01,,,32,32,7
PS2,,,57$PL,01.,
$GPRMC,042117.00,V,,,,,,,100913,,,N*76
$GPVTG,,,,,,,,,N*30
$GPGGA,042117.00,,,,,0,00,99.,,,
$,1,,,,9,.,9*0$G2,,,16,,,42,4
$S,262,2,4A
PL,01,N
$GPRMC,042118.00,V,,,,,,,100913,,,N*79
$GPVTG,,,,,,,,,N*30
$GPGGA,042118.00,,,,,0,00,99.9,,6
SA,,,,9999993
PV155,,,11,,,37
PV,02,68$G,,410V

[snip]

PV,02,*
$G,,420V
$GPRMC,042121.00,V,,,,,,,100913,,,N*73
$GPVTG,,,,,,,,,N*30
$GPGGA,042121.00,,,,,0,00,99.9,,*
SA,,,,,99999*
GV,01,,,32,62,7
PS,,,,47$PL,01.,E$GPRMC,042122.00,V,,,,,,,100913,,,N*70
$GPVTG,,,,,,,,,N*30
$GPGGA,042122.00,,,,,0,00,99.9,,6
S,,,,,9999993
P,155,1,81,,,37
PV,02,*A$G,,420V
$GPRMC,042123.00,V,,,,,,,100913,,,N*71
$GPVTG,,,,,,,,,N*30
$GPGGA,042123.00,,,,,0,00,99.9,,6$A,,,,,9999990$P,15,21,9132,3A$G,202,*
GG,,420V
$GPRMC,042124.00,V,,,,,,,100913,,,N*76
$GPVTG,,,,,,,,,N*30
$GPGGA,042124.00,,,,,0,00,99.9,,6
S,,,,,,999993
PV,55,,,91,,,,7
PV,0,,68$G,,02.,
$GPRMC,042125.00,V,,,,,,,100913,,,N*77
$GPVTG,,,,,,,,,N*30
$GPGGA,042125.00,,,,,0,00,99.9,,6
A,,,,,9999993
P,155,1,91,,,37$GV,02,*9$G,,420V
$GPRMC,042126.00,V,,,,,,,100913,,,N*74
$GPVTG,,,,,,,,,N*30
$GPGGA,042126.00,,,,,0,00,99.9,,6
SA,,,,9999993
PV,05,,,39,,,,7
PV,02,24,*
$L,,40,4$GPRMC,042127.00,A,4458.79572,N,09311.14975,W,0.881,,100913,,,A*6C
Latitude.: 44.98
Longitude: -93.19
Altitude.: 1000000.00
Satellites: 255
Age……: 145
Chars….: 7642
Sentences: 0
Failed…: 58

[snip]

Hi MIkal, I am interested in reading the definitions of the functions in the TinyGPS library. Can you help me with this? Nice work by the way, thanks a lot for your great work.

Hi,
I am working with Leica DGPS Receivers that give accurate results in the cm range. The NMEA sequences are the same as usual, but GGA and RMC have more digits, like

$GPGGA,102644.00,4813.7943164,N,01621.5693035,E,2,05,2.3,215.472,M,,,0.00,0000*2B

TinyGPS++ can parse the sequences OK, but the transformation to floats is not accurate to the last significant digit:

4813.7943164 (NMEA) should Output 48.229905273 (degree)

TinyGPS++ converts the Latitude to 48.229904174
I think this Comes with the Int/float conversion that is internally done in TinyGPS++

The error does not occur with plain vanilla GPS Receivers that are limited in their accuracy anyway.
Do you have any idea how this could be solved? Unfortunately C/C++ is not my first language so I am more or less at a loss when trying to change the conversion Routines

Thanks!
Bernhard