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Topic: 2 months with the same problem GPS give rubbish with Arduino Uno. (Read 6900 times) previous topic - next topic


Well so far we do not have a link to the data sheet for the device, we do not have an adequate unambiguous description, photograph, or diagram of the interconnections, and we do not have a copy of all of the code.  Otherwise we have everything we need to provide an intelligent response to his questions.



There is a small mistake of } on the last message I posted... pls disregard.

Why don't to fix it? There is a "modify"-button to edit previous posts.

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Note to self: "Damn! Why don't you just fix it!!!"


You should connect the GPS to pins other than 0 and 1 - so connect them to pins 2 and 3 and use newSoftSerial to talk to the GPS.  From a quick google search it looks like you should be using 9600 as the rate.

Also, the Serial function is so you can talk to the IDE via the debugger and you can't overlap it with the GPS.  You need Serial to talk to the debugger and NewSoftSerial to talk to the GPS.

So you need two serial functions like so:

Code: [Select]
#include <NewSoftSerial.h>

NewSoftSerial nss(2,3);

void setup()
  lcd.begin(16, 4);           
  pinMode(rxPin, INPUT);
  Serial.begin(9600);         // for the debugger
  nss.begin(9600);           // for the GPS on pins 2 and 3


I tracked down a copy of the SkyTraq S1315F (FLASH version of the S1315R ROM version)

It says 9600 baud.
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thanks for you replies,

Daneel, I will try what you said and update you as soon as it is finished


Well, Daneel it still give rubbish. I order a new arduino... since I played a lot with this one I wander if I have not damaged it... or something.... I will check with the new one and give some updates...


Hello guys, as posted at the start I get rubbish from the GPS S1315R the I have. I try all the code that I could find online with the same result: rubbish.
I went through the datasheet again

I am using the max232 that give TTL.

is there any possibility that the problem might come from a non matching device?

thank you


I am using the max232 that give TTL.

That sounds like a mismatch right there. a max232 is designed to convert from RS-232 voltages (+/- 3 to 15vdc) to TTL digital. But what it also does is do a logic inversion on the data line. As your device is already outputting a 3.3vdc LVTTL level, that logic inversion (going through the max232) is flipping the serial data upside down. You should just wire the GPS ground to arduino ground and the 3.3v serial output pin to your arduino digital input and try and read the data, it should work unconverted (and unmolested).



Lefty... you are really what I call ENGINEER...

in fact I the max232 inverted incoming data... so rubbish was outputed all the time no matter the code.

thank you ever so much and very a lot


in fact I the max232 inverted incoming data

Pointed out in reply #12.

EDIT: Also, I notice, pointed out in reply #2!
"Pete, it's a fool looks for logic in the chambers of the human heart." Ulysses Everett McGill.
Do not send technical questions via personal messaging - they will be ignored.
I speak for myself, not Arduino.


Imagine how much faster he might have solved this if he had responded to #15.



It appears that you are looking at a data sheet for a different GPS module than the Skytraq S1315F. The S1315F does speak NMEA but it is best used in the Skytraq binary format. Which I am sure is what you are seeing.

You can get very accurate position fixes with the S1315F but you either need access to a nearby base station's data or you need two receivers, one stationary, one moving..and realtime calculation of your position using both is such a heavily CPU-intensive task that Arduinos can't do. However, lots of other CPUs can.

However, if you download Skytraq's GPSviewer software you should be able to easily switch it to NMEA and write the configuration to flash- then you will have a very nice GPS chip capable of 20 Hz updates. The serial port speed can vary from 4800 baud to 115200. Its configurable.

For how to use the binary data, see http://gpspp.sakura.ne.jp/rtklib/


Friend will2is,

Did you solve the problem ?
Did you get the position's coordinates ?
I wanna use a gps S1315R with arduino. Could you give the way step by step?

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