I just brought GPS module "Global-Top GMS-U1LP". I want to setup it for its UART configuration. In data-sheet there are 4 different ground but I am not able to trace which ground corresponds to which power input or for data. Gms-u1lp dtatsheet So with lot of doubt in mind I made following setup.

Is this configuration correct?enter image description here

original setup according to data-sheet is as below: enter image description here

Does anybody know how to setup this GPS receiver IC?

  • 1
    \$\begingroup\$ your diagram looks correct, but i would connect all gnd pins to ground, and also connect a backup battery to keep the RTC going. all the pin connections start on page 11 of the datasheet you linked... it looks like a lot of pins need to be left floating (not connected).....other then that it looks good :) \$\endgroup\$
    – jsolarski
    Feb 3, 2011 at 9:10

1 Answer 1


All four pins are Ground, and all four pins should be connected to your circuit ground.

It may work if you leave some of the ground connections floating, but you may have reliability issues.

That GPS module does not have separate ground domains. Basically, to reduce the impedance of the ground connection, and possibly for reliability issues, they are using multiple connections from the same ground.

It is in-fact likely that if you use an ohmmeter to measure the resistance between she separate ground connections, you will find they are coupled together within the GPS module as well. You should still ground them all, however.


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