GPS Module problem

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GPS Module problem

Postby Herath » Sun Dec 26, 2010 5:34 pm

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Re: GPS Module problem

Postby Neo » Mon Dec 27, 2010 7:07 am

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Re: GPS Module problem

Postby Herath » Mon Dec 27, 2010 9:08 am

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Re: GPS Module problem

Postby Neo » Mon Dec 27, 2010 9:43 am

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Re: GPS Module problem

Postby Herath » Mon Dec 27, 2010 9:47 am

When I checked with SiRFDemo, it is enabled. I disabled it. Seems like when disabled, module does not get a fix for a very long time. But that's only in NMEA mode. If I switch to SiRF mode and use it with SiRFdemo everything works fine.
I could read heading value, velocity updates properly, location updates properly etc. But in NMEA mode, i could not get them. I guess that there is something wrong with the NMEA processing in the module. :(
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Re: GPS Module problem

Postby Neo » Mon Dec 27, 2010 1:38 pm

I'm not sure what's going on with NMEA on your chip. Are you sure the baud rate is set correctly on the module ?

In some forums, I found some information that may be related to your issue.

First, try to disable "Synchronise Protocol and baud rate" on SirfDemo.

Second thing is to use baud rate 38400. I think this is the baud rate of GPS chip. Try baud rate 4800 as it is the standard baud rate for NMEA.

Thirdly, when NMEA isn't working over SirfDemo, it is required to detach the batteries and do a hard reset. Since yours is USB powered, I don't think this is relevant. But it could be helpful if you remove it from power and keep it a day until all condenser charges are gone.
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Re: GPS Module problem

Postby Herath » Mon Dec 27, 2010 1:51 pm

The default baud rate is 4800bps. I will try using 38400bps. And NMEA does not work over SiRFDemo( I can only see NMEA sentences in debug view, but software does not show any information), only SiRF Binary work. The module has an internal battery. I guess that I will have to remove that too. Although the module is battery backed up, every setting is lost as soon as I remove power to the module. I did not check the battery to see if it is soldered to the board since I need to remove insulation to check it.

I collected more data in the evening. The track made using the GPS points does not seem to be the way I went. It is wrong(impossible points ) at some points.

I also suspect if there are any problem with the connection. But, I receive data without errors, and I can send commands to it properly. the cable I am using can handle 115200bps easily. I tried enabling debug messages but the module does not respond to that command.

I will try to get NMEA working. Since it is easy to work with than SiRF Binary.

Thanks.

----------------------------------------------------------------
Edit:
I desoldered the button battery on the board. It still does not respond to VTG enable.Anyway, I will leave it that way for about a day and check again.
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Re: GPS Module problem

Postby Herath » Fri Dec 31, 2010 6:51 pm

Resoldered the battery. Can't enable the VTG still. But I get heading value when I pass 1.4m/s velocity limit. :D. Traveling in bus cause the module to update the location at 1Hz. If I turn off static navigation, values gets really crazy. So, static navigation should be there for greater good. :)

[behind cover story]
Connected the module to laptop, installed Bluesoleil to get Serial Port Profile on my laptop. Then wrote a little app using .NET to read from GPS serial port and write to Bluetooth Serial port. Then I made a huge hardly portable Bluetooth GPS reciever.  :mrgreen:
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Re: GPS Module problem

Postby Neo » Sat Jan 01, 2011 8:10 pm

Cool... Good to see some progress with this now even in the hard way.
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