Pages: [1]   Go Down
Author Topic: GPS returns "yyy.."  (Read 741 times)
0 Members and 1 Guest are viewing this topic.
Offline Offline
Full Member
***
Karma: 0
Posts: 174
View Profile
 Bigger Bigger  Smaller Smaller  Reset Reset

Hi there!

I guess my problem is somehow obvious to solve, but I can't see it. I'm using a Fastrax UP-501 GPS Device and an Arduino Duemilanove.

Datasheet of the GPS: http://dlnmh9ip6v2uc.cloudfront.net/datasheets/Sensors/GPS/UP501.pdf

The GPS is powered via the Arduino 3V3 and GND pins. I connected RXD and TXD to digital pins 2 and 3.

The Code:

Code:
#include <SoftwareSerial.h>
SoftwareSerial GPS = SoftwareSerial(2,3);

void setup(){

  Serial.begin(9600); 
  GPS.begin(9600);
}

void loop(){

GPS.listen();
  Serial.write(GPS.read());

}


The only return I get on the Serial Monitor are some weirdlooking y's.

Thanks!
Logged

Canada
Offline Offline
Jr. Member
**
Karma: 1
Posts: 81
Frequently Befuddled
View Profile
WWW
 Bigger Bigger  Smaller Smaller  Reset Reset

It sounds like a baud rate problem to me.

Despite the datasheet saying 9600 baud, for some reason I seem to recall using 4800 with the UP501.

Try setting your GPS.begin to 4800 and see if that helps?

Cheers!
Logged

Miramar Beach, Florida
Online Online
Faraday Member
**
Karma: 138
Posts: 5840
View Profile
 Bigger Bigger  Smaller Smaller  Reset Reset

The "funny y" is ascii character 255. That is also signed -1, meaning "no characters available yet". You must wait until it sends something. I would try something like this

if(GPS.available()) {
  Serial.write(GPS.read());
}

Logged

Offline Offline
Full Member
***
Karma: 0
Posts: 174
View Profile
 Bigger Bigger  Smaller Smaller  Reset Reset

Thank you for your answers.

Unfortunately both did not help. Since I added the if available part, I just receive nothing.
Logged

Offline Offline
Full Member
***
Karma: 0
Posts: 174
View Profile
 Bigger Bigger  Smaller Smaller  Reset Reset

Since no data seems to be available, I'm wonderig if my wiring is faulty. (I had the same result with my Mega)

As you can see in the datasheet the GPS has 6 pins. The PPS and backup VDD are not in use in my wiring.

I hooked the RXD to RX (as defined in the SoftwareSerial) and the TXD to TX. VDD goes to 3V3 and GND to GND. Is there anything I could measure to test? (there is power on the GPS)
« Last Edit: August 15, 2012, 01:41:44 pm by GoingForGold » Logged

Offline Offline
Full Member
***
Karma: 0
Posts: 174
View Profile
 Bigger Bigger  Smaller Smaller  Reset Reset

Nevermind, I got it!

First, I did not read that you have to connect the backup power too, and second, I did not realize that RX and TX are each of "their" view, so you have to switch them.

But now, one other question: I can talk to my GPS to set some settings. How do I do this? Just by GPS.write(...)?

Thanks again!
Logged

0
Offline Offline
Faraday Member
**
Karma: 8
Posts: 2526
View Profile
 Bigger Bigger  Smaller Smaller  Reset Reset

You're lucky you haven't killed it.  Dataasheet says:

Quote
Input voltage on any input connection  +3.6V

TX on the arduino is 5V.

-j
Logged

Seattle, WA USA
Offline Offline
Brattain Member
*****
Karma: 601
Posts: 48543
Seattle, WA USA
View Profile
 Bigger Bigger  Smaller Smaller  Reset Reset

Quote
But now, one other question: I can talk to my GPS to set some settings. How do I do this? Just by GPS.write(...)?
Or GPS.print(), depending on what you are trying to send it. Most likely, GPS.print() will work better. It will call GPS.write() to actually send any formatted data.
Logged

Pages: [1]   Go Up
Jump to: