GPS module (part 28146) communication problem
jruthroff
Posts: 38
Hello all,
I'm attempting to run the demo program for the GPS module (part 28146) on a Stamps in Class board (USB version, revision D) with a BS2 stamp and PBasic language 2.5. The demo program (GPS DemoV1.1.BS2) I've downloaded from Parallax.
The connections seem pretty straighforward, the GND termial on the GPS goes to Vss on the board, the VCC terminal on the GPS goes to Vdd on the board, and SIO on the GPS unit goes to pin 15.
When I power-up the board, the DOWNLOAD PROGRESS window appears, and after scanning the ports I get a "COMMUNICATIONS ERROR...No BASIC Stamps found" error.
When I disconnect the either the ground or VCC jumper (i.e., when I take power off the GPS module), and rerun the program, the program downloads successfully. Of course it doesn't work since the GPS module has no power, but it does at least download and try to run (it reports, not surprisingly, "no respones from GPS receiver".
I'm probably misssing something very basic here, but any help would be appreciated.
Thanks,
John
I'm attempting to run the demo program for the GPS module (part 28146) on a Stamps in Class board (USB version, revision D) with a BS2 stamp and PBasic language 2.5. The demo program (GPS DemoV1.1.BS2) I've downloaded from Parallax.
The connections seem pretty straighforward, the GND termial on the GPS goes to Vss on the board, the VCC terminal on the GPS goes to Vdd on the board, and SIO on the GPS unit goes to pin 15.
When I power-up the board, the DOWNLOAD PROGRESS window appears, and after scanning the ports I get a "COMMUNICATIONS ERROR...No BASIC Stamps found" error.
When I disconnect the either the ground or VCC jumper (i.e., when I take power off the GPS module), and rerun the program, the program downloads successfully. Of course it doesn't work since the GPS module has no power, but it does at least download and try to run (it reports, not surprisingly, "no respones from GPS receiver".
I'm probably misssing something very basic here, but any help would be appreciated.
Thanks,
John
Comments
What's happening is that, when the GPS module is powered, the current demand becomes maybe 150mA. The AC supply can't provide that much and its output voltage drops. When the output voltage drops below around 5.5V, the regulator stops regulating. When the supply voltage drops below around 4.5V, the Stamp detects this and stops working (goes into reset).
Regards,
John
Using
Ardiuno 2009 with the parallax GPS Module 28146.
Where are you when this is happening? If you are inside, standing close to a building, under dense trees, these things can block some of your signal from the satellites. If you haven't already, try standing outdoors, in a clear area, with a clear view of the sky to the North (assuming you are in the Northern Hemisphere). This is usually the best condition for GPS satellite reception. If you still need 20 minutes to lock in a position from there, you could have other issues. If you have access to a method of reading the NMEA sentences from your GPS unit, check for the $GPGSV sentences. In most cases, if you are in North America, and following the directions above, your unit should display three lines of $GPGSV together each time it sends them. These three lines should probably display information for 10-12 satellites - some may have good signal strength, and others may not. If you go on the Internet and get a good description of this NMEA sentence, you can learn to decode the information your unit is getting from each satellite that it sees. Once you learn to read this code, you will have more information about how well your unit is receiving data, how many satellites it 'sees', etc. Maybe some of that will help you figure out how well it is actually receiving.