MOD-GPS problem

[yuribit]

Hi everybody,

I've just bought a MOD-GPS with MT3329 MEDIATEK chip but I'm having some troubles when I try to connect it with my Olimexino STM32.

I've connected the GPS module using a USB-UART converter and it works fine.

I've discovered that the Olimex board is not giving enough power to the GPS module.
Did anybody have the same problem?

Thanks,
Yuri

[LubOlimex]

Hey Yuri,

Have you tried to connect the GPS module (MOD-GPS) on the UEXT connector of Olimexino STM32? There is a ready example for such a connection (though I'm not sure which chip was in the MOD-GPS back then, it might need a slight adjusting): https://www.olimex.com/Products/Duino/STM32/OLIMEXINO-STM32/resources/OLIMEXINO-STM32+MOD-GPS_v.1.0.zip.

If you power the board from the USB only, please try on another USB port/USB hub or another computer (some computer USB ports get damaged easy or might provide lower voltage than needed). Have you tried with external power supply?

Have you measured if there are 3.3V on the UEXT of OLIMEXINO STM32?

Best regards,
Lub/OLIMEX

[yuribit]

Hi LubOlimex,

The first thing I've tried is to connect the Olimexino with the MOD-GPS using the UEXT connector and then I run the example you suggested me. The MOD-GPS red led didn't blink and I didn't receive any information from it, the serial monitor remained blank waiting for data.

Then I've tried changing USB port also with different computers or using a 3.7V battery fully charged but nothing changes.

I've misured the power on UEXT connector of my three Olimexino STM32 and it is 3.28V while the power misured on USB-UART (where the MOD-GPS works) is 3.3V.

Do you have any suggestion?

If I give the power to the MOD-GPS from the battery and connect only the tx pin of the UEXT connector it works but this is not a good solution.

[LubOlimex]

Unfortunately, it is possible that there is little less than 3.3V on the UEXT and the new MOD-GPS requires a little bit more than 3.3V (3.32 in my observations).

The bad thing is there is not much that can be done on hardware level of the OLIMEXINO-STM32 - since there is an IC that handles the power (VR2 MCP1700T-3302E/MB that is).

The only solution so far is the one mentioned by you, and I know that is not good but there is no better at the moment. We are looking for other options.

Best regards,
Lub/OLIMEX

[yuribit]

This is the solution I adopted. It isn't nice but I think that there aren't other solutions.
I bring the 5V from the C20 condenser.

Hope this can be useful to someone in future (obviously a different board is the best choice)