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Gms-U1lp always hang up

Started by JNeumann, May 12, 2011, 11:30:14 PM

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I got a problem with the Gms-U1lp GPS Receiver. As Horsa is in Holiday, maybe someone else have a Idea to try / help.
The main problem is, that the Receiver will hang up / take a time out during driving in my Car, but the Time is always beeing updatet.
I use it @10Hz with 115200 Baud.

For example: I have to Stop on a red Traffic Light. After the Car is standing still, the GPS-Speed will go down to zero (very slow, even if the Car is still standing for a few seconds, the showed Speed goes down from e.g. 30km/h.

If the traffic light get´s green and I go on, the Speed shows 0 km/h. Sometimes a few seconds, sometimes more than 1 minute.

I checked my Hardware and Software with an Fastrax UP501B, nothing else changed, and this works fine.
So I think it´s not related to my Programm or my Hardware Setup, as both Receivers use the MT3329 Chipset.
But the Fastrax Receiver is too big and I need the one-sentences output and Geofencing, so I want the Gms-U1lp Receiver to work good.

The Receiver is connected regarding the Datasheet. The VPP ripple is at ~18mV.
For the Power I use an MP2357 switching regulator, even with a Linear regulator @3.3V the problem still exists.
The Receiver is soldered on a big Ground Plate, 86mm x 52mm, together with an SD Card Holder.
The Electronic is inside an ABS-Plastic Case. I test everything behind my Cars Frontwindow (NO Sunprotected Glass).

The Firmware is AXN-1.50

Does anyone have an Idea about that problem ?



Dear JNeumann,

some weeks ago we sent you two golden (= known good) firmware restore files. One for 1 Hz update rate (factory default) and one for 10 Hz.
Please let us know the results of your tests for these reference firmware settings.

- Horsa


Dear Horsa,

I was a long time away for my Company and be back right now.
I had checked the 10Hz Firmware you send me. The firsts test looking good, much better than before.
I hope I can do a long test next week and let you know the Result asap.