[G Tablet General] fosser2:
UPDATE 5/26/2011

: I have put together a tutorial and will keep it updated. It can be found at this link. http://xdaforums.com/showpost.php?p=14111386&postcount=207 The project is not fully completed but working! Keep following us as we progress through this thread.

Ok, I’ve been digging around recently and have been getting nowhere. From a bunch of emails and PM’s that took me a long time to write, I have gotten nothing back. So I am starting a new thread here.

I am in the process of finding info on the internal GPS module that the G-Pad is capable of having installed. I am willing to use my tablet as a demo to see if I can get it working! If it works, I will make a detailed thread on how to go about installing a GPS module into the G-Tablet. So speak up if you know your electronics please!!! :p

What I have compiled so far

A member from XDA forums literally bought a kit (eBay Post) that enabled GPS use. He posted that the chip that he installed was a RXM-GPS-SG-B found at this link (http://search.digikey.com/scripts/DkSearch/dksus.dll?lang=en&site=US&KeyWords=RXM-GPS-SG-B&x=0&y=0). After looking at the data sheet for this chip I’m pretty sure that this chip will work on the G-tablet board. All of the pins line up properly and everything. In the XDA post that I read, after the install of the chip he posted “I now have power to the chip and its working. When I click on the place app now it no longer just says wait but comes up with aps where to go.” This is a good sign in that it is already enabled in the VS bootloader kernel. Basically if you can get it soldered in and enabled it should work. The problem is that he claimed that pin 12 (vcc) did not have power and he had to power it from another source. He claimed that he tapped into the USB +5v power. That would have worked ok if the GPS chip needed 5v power. The chip itself needs 3.3v of power. This user was overvolting his GPS chip from the get-go. He had reported some issues with it and I think that this overvolting was part of the problem.

Here is a picture of the installed chip via the XDA forums. Sorry for the smallness it was as big as I could find. http://xdaforums.com/attachment.php?attachmentid=585865&stc=1&d=1304460793

My theory is that you can tap into the 3.3v pin that is located on the mini PCI e headers and use this for power. This will provide the correct voltage. Here is a picture of the empty spots on the board. http://xdaforums.com/attachment.php?attachmentid=585866&d=1304460792

As you can see in the picture above there is an “empty” power circuit located below where the GPS chip would reside. I read a post on XDA that claimed that if properly hooked up correctly it would probably produce the 3.3v output needed for the GPS chip also. The items that the user claimed could possible make it work were as follows.

http://search.digikey.com/scripts/DkSearch/dksus.dll?Detail&name=NCP51460SN33T1GOSCT-ND Part# NCP51460SN33T1G

http://search.digikey.com/scripts/DkSearch/dksus.dll?Detail&name=NCP551SN33T1GOSCT-ND Part# NCP551SN33T1G

I do not have enough knowledge about IC’s to know how these are used. If anyone has an idea let me know. They go in the power circuit somehow.

The next part is the antenna connector. This would get installed in the empty “ANT2” connector. This should be an easy mount and is exactly how “ANT1” the wifi antenna is connected. http://xdaforums.com/attachment.php?attachmentid=585863&d=1304460740

http://search.digikey.com/scripts/DkSearch/dksus.dll?Detail&name=H9161CT-ND Part# U.FL-R-SMT(10)

Finally onto the antenna itself. Although I have read that a passive antenna can be hooked up to this chip, an active antenna seems like it would get much better reception. The antenna that I have read a lot about is the following.

http://search.digikey.com/scripts/D...&lang=en&site=us&keywords=931-1014-ND&x=0&y=0 Part# ALA.01.07.0095A

This antenna would literally just snap onto the antenna 2 connector and it should work. Now to run an active antenna the GPS data sheet says that a 300ohm ferrite bead needs to be installed. This is the part where the member at XDA also messed up. He wired an antenna with a 300ohm resistor thinking it worked the same as a ferrite bead. A ferrite bead basically reduces any interference coming from the antenna going to the chip. Here is a link to the proper ferrite bead.

http://search.digikey.com/scripts/DkSearch/dksus.dll?Detail&name=445-6406-1-ND Part# MMZ1608D220C

The ferrite bead is also where I have run into problems. I do not know how to properly install one of these and I have no idea if there is even a spot on the board to do so. Any help in this area would also be appreciated. http://xdaforums.com/attachment.php?attachmentid=585873&stc=1&d=1304461146

The antenna should be able to fit in the plastic up at the top of the case while also providing ample reception.

After all of this is installed hopefully the GPS chip will work. Although this sounds like a complicated project there is not actually that much soldering to do. The main GPS chip is actually most of the soldering. I am hoping that someone reads and appreciates that work that I have compiled/done so far. Any help on this project would be greatly appreciated.

Also please do not post “why don’t you just use an external Bluetooth module.” I get that these work great, but I just want to see if the internal GPS will function.

Attached below is everything I could possibly obtain after browsing through the entire internet looking for any type of documentation on this project :p Thanks for taking time to read through this post.

Last Thoughts

Here is a more in depth picture that shows the GPS connection and GPS schematic from the datasheet. It is very helpful. http://xdaforums.com/attachment.php?attachmentid=585868&d=1304460792

I posted datasheets as attachments for the GPS Module and the Antenna I hope this helps out. http://xdaforums.com/attachment.php?attachmentid=585875&stc=1&d=1304461367

Here is the entire system board for those who need a complete picture. http://xdaforums.com/attachment.php?attachmentid=585867&d=1304460792

References

Thanks to the following people from XDA

mystkrh

6.055chevy

vsc

also to anyone I missed sorry