STM CircleOS forum / GPS intereference?

krheinwald · 2009-08-24 12:50:56

Today I connected a Navilock NL-507ETTL (based on the ublox Antaris chip) to get started with the GPS projects from the projects page.

In order to test the basic funtionality, I only connected GND on the extension connector and Vcc directly to the jumper used to connect the internal LiIon battery.

The GPS gets and holds a fix when the Primer is turned off, but once it is turned on by pressing the joystick, the fix is lost and hardly returns. The only explanation I can think of is noise emitted by the Primer, probably made worse as the extension area is directly belo the processor.

Did anyone else notice this and how did you solve it? How did the two projects dealing with GPS handle this?

Klaus

ShadowPhoenix · 2009-08-27 03:44:45

can you connect wires to outside of the chassis and try the GPS chip from there? Dangling outside the primer?

What's the voltage requirment? or just post a datasheet linky.

krheinwald · 2009-08-28 13:48:54

Extending the cables came to my mind as well. I'll try it once I'm home again.

Supply voltage is specified as 3V-5V in this document: http://www.navilock.de/download/Dokumen … Module/481

Klaus

ShadowPhoenix · 2009-08-30 05:01:54

Hmm on the second thought connect to extension connector (pin 1/2)
Check the primer 2 manual, section 2.8, and use those pins instead of the jumper one.

Then see how it works dangling outside.

krheinwald · 2009-09-03 08:31:47

A quick update on my progress:

I started by extending the wires by 30cm which brought only a small improvment. Moving GND from pin 2 to 20 improved it a little bit more. Soldering the wires directly to the battery leads improved it further. As I suspected the interference came across the wires, I ran the wires through a ferrite ring, which also helped.

All this was tested away from the case. When I put the unit back into the case, the fix was lost again.

As I received a second Primer last week, I switched over to that unit an - surprise! - the GPS works on short wires inside the case. Seems to be a problem with that specific Primer.

@Shadow: Pin 2 has only 2.8V, not enough to run the GPS.

Thanks for you help,
Klaus

# 1 2009-08-24 12:50:56 GPS intereference?

GPS intereference?

# 2 2009-08-27 03:44:45 GPS intereference?

Re: GPS intereference?

# 3 2009-08-28 13:48:54 GPS intereference?

Re: GPS intereference?

# 4 2009-08-30 05:01:54 GPS intereference?

Re: GPS intereference?

# 5 2009-09-03 08:31:47 GPS intereference?

Re: GPS intereference?

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