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Weird baud rate

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Thanks Horsa. I'll send the SN information.

Posting the following information would also be very useful for further investigations:

* a screen shot of the module running at 24400 bps
* data log (using mini GPS tool) of the module running at 24400 bps
* Which method was used to power cycle the module? Was it through enable pin or by cutting the power to VCC?
* schematics to the main-board connected to GlobalTop GPS module
* a picture of the main-board
* check that the Vcc ripple is controlled under 50 mVpp
 - Horsa


Almost 2 year later.
I found those GPS modules inside a drawer and decided to play with then again, since i'll need a gps in another project.
Still (even after 2 years disconnected) running at 24400bps.
So, I decided that it is a faulty module. replacing with the other module that i have (same batch, never used).
It is too at 24400bps. I just turned on my hardware and it started to receive nmea messages at 24400bps.
So, I don't think it's hardware.
Being a firmware problem, does anyone managed to solve it? I've tried to send messages to the module but it seems to ignore all of them no matter which baud rate.

Thanks, Mauricio

I found a solution for the problem.
If you power up those modules with the 3D-fix output connected to a LED attached to VCC, instead of GND (I wanted the LED On when there is a Fix) the module will start running at 24400bps.
No idea why this happens, but it does. After changing the LED from VCC to GND the module started to output messages @ 38400bps. Now I'll try to send packets to configure it.
Hope it can help other people too.

Thank you for your perseverance. We eventually got it.

This issue is described in "GPS Module Application Notes".

The 3D-Fix pin can affect the internal crystal oscillator (not the TCXO). If the 3D-Fix pin is connected directly to Vcc like you did, the MediaTek chip sets the internal crystal oscillator frequency to 20 MHz instead of the regular 32.768 MHz. This is why your baud rate changed to 24400 b/s instead of your expected 38400 b/s:

* 24400 / 20000  ~=  1,2
* 38400 / 32768  ~=  1,1


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