[GUIDE] How to install Internal GPS Module

jmdearras said:

I have been over the specs on the GPS and the regulator. as far as I can see, it should not have caused any trouble. If you installed the 1uf caps backwards, that would have been a problem, and quite possibly running the regulator without it's filter caps could have caused it to oscillate. Or the part could have been damaged.

But from the specs on the GPS chip, it's not really needed. I will install my regulator first, and test for correct operation, to verify all this. Parts arrive Friday.

Jim

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Honestly, maybe it was a faulty part? i have no idea. If everyone says that it should work than maybe it does? Let me know when you get your parts.

Jim[/QUOTE]

manikin13 said:

Fosser2,
You mentioned using the gps for a trip around town. Was it a long enough test to determine battery life effect?

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Ha, no sorry I was not watching the battery life. From what I've seen during testing the battery holds up surprisingly well. Imo, I would say that when you are out and about with the tablet you are not connected to wi-fi. Meaning you are really now wasting any more battery. I would say that the tablet wi-fi = gps. So you would get the same hrs of use if you were to use your tablet constantly with the screen on and wi-fi. This is just a guess

Official Tutorial

Ok, here is the tutorial that people have been waiting for. It is not a complete finished work of art and will have changes made to is as discoveries are made.

Disclaimer: Please do not attempt this project unless you really understand the risks of soldering onto a circuit board. This could end up frying your G-Tablet if you are not careful and I take no responsibility if anything bad happens to your tablet.

That said, this has been a very enjoyable project and greatly improves the usability of the G-Tablet. If you have the balls to do this, I think this mod is very useful.

Parts List: (thanks to twistedrotors)
*U28 GPS Module - RXM-GPS-SG-B-ND http://search.digikey.com/scripts/D...g=en&site=us&keywords=RXM-GPS-SG-B-ND&x=0&y=0

*U29 5vdc VCC Reg - NCP551SN33T1GOSCT-ND http://search.digikey.com/scripts/DkSearch/dksus.dll?Detail&name=NCP551SN33T1GOSCT-ND
C348 - U29 In to GND (0.1 uf 0402) - 445-3445-1-ND http://search.digikey.com/scripts/DkSearch/dksus.dll?Detail&name=445-3445-1-ND
C349 - U29 Out to GND (1.0 uf 0402) - 445-4978-1-ND http://search.digikey.com/scripts/DkSearch/dksus.dll?Detail&name=445-4978-1-ND

̶U̶2̶2̶ ̶3̶.̶3̶v̶d̶c̶ ̶B̶k̶p̶b̶a̶t̶t̶ ̶R̶e̶g̶ - ̶M̶C̶P̶1̶7̶0̶0̶T̶1̶8̶0̶2̶E̶T̶T̶C̶T̶-̶N̶D̶ http://search.digikey.com/scripts/DkSearch/dksus.dll?Detail&name=MCP1700T1802ETTCT-ND (This part does not work. I have tried in 2 tablets now and it just makes the tablet not boot. Just jumper this location.)
C347 - U22 Out to GND (1.0 uf 0402) - 445-4978-1-ND http://search.digikey.com/scripts/DkSearch/dksus.dll?Detail&name=445-4978-1-ND
C355 - U22 In to GND (1.0 uf 0402) - 445-4978-1-ND http://search.digikey.com/scripts/DkSearch/dksus.dll?Detail&name=445-4978-1-ND

*L11 Ferrite Bead - 445-2171-1-ND http://search.digikey.com/scripts/DkSearch/dksus.dll?Detail&name=445-2171-1-ND
(This ferrite bead is the one that I am using. There have been a few different ones recommended in this post including this one also (240-2391-1-ND. Mine seems to function the proper way.)

*U34 Voltage Level Translator - 296-21978-1-ND http://search.digikey.com/scripts/DkSearch/dksus.dll?Detail&name=296-21978-1-ND
R302 – (1k ohm 0201) - P1.0KAGCT-ND http://search.digikey.com/scripts/DkSearch/dksus.dll?Detail&name=P1.0KAGCT-ND
C273 – (0.1 uf 0201) - 445-4711-1-ND http://search.digikey.com/scripts/DkSearch/dksus.dll?Detail&name=445-4711-1-ND
C272 – (0.1 uf 0201) - 445-4711-1-ND http://search.digikey.com/scripts/DkSearch/dksus.dll?Detail&name=445-4711-1-ND

*ANT2 Antenna Connector U.FL - H9161CT-ND http://search.digikey.com/scripts/DkSearch/dksus.dll?Detail&name=H9161CT-ND

*ANT Antenna (Active) - 931-1014-ND http://search.digikey.com/scripts/D...&lang=en&site=us&keywords=931-1014-ND&x=0&y=0

Parts that are needed have an "*" in front of them. Most of the capacitors and resistors are not needed but "should" be there because thats how the company intended. I personally, have not used any of them .

Non-Digi-Key Supplies:
Flux: http://www.radioshack.com/product/index.jsp?productId=2049774
LED: http://www.radioshack.com/product/index.jsp?productId=3496417
Multimeter: http://www.amazon.com/Equus-3310-Ha...EXWA/ref=sr_1_6?ie=UTF8&qid=1306286612&sr=8-6

Step 0: Please remember where things go while you take apart your tablet. This is not a tutorial explaining to take out specific screws and put them back. Common sense is needed in doing this mod.

(ok, onto the good stuff )
Step 1: Remove tablet backing.
This is done by using a small screwdriver to pry out the 4 rubber pads on the backside of the tablet. If done properly they should not scuff or make marks. After these are out 4 screws will be exposed, remove those with a phillips head screwdriver. Next near the dock connector (bottom of the tablet) slide a credit card in the slot where the plastic on the tablet comes together. There are 3 clips holding the plastic backing per side so, sliding the credit card around the tablet should pop them out of place. Do this with your tablet face down. If done sucessfully, the tablet should pop apart. You should see something like the following.
With just the tablet backing off, you should be able to solder most components just like this (excluding the chip on the backside).

Step 2: Pre-solder the pads.
This is how I started off my project. UNPLUG THE BATTERY BEFORE SOLDERING. When soldering components onto the board it was nice to have pre-solder already layed on the board. If there is a better way to do this let me know, but this method is what I used. For starters use a pencil eraser to clean off the pads that you will be soldering. This makes the surface as clean as possible to solder on. Next each pad has to be soldered. To do this flux the areas that will have solder applied to them. Then put solder on the tip of your iron. Quickly touch the points that components will be soldered to (do not overheat). You will notice solder flow from the tip of the iron onto the pad. Do not put too much solder on the pads. Below is a picture of the board and the blue areas are where "pre-solder" should be applied.

Step 3: Solder on GPS Chip (RXM-GPS-SG-B-ND)
I figure since this is the biggie of the project why not start with it Take the GPS chip and align it in the proper orientation. Here is how the chip should sit.
Once you have the chip alligned, flux one side of the chip and apply some more flux on the board. Put more solder on the tip of your iron and quickly run it along one edge of your chip. If done properly, the pre-solder should "flow" onto the chip. The added solder on your gun should ensure a secure connection. If the solder does not flow perfectly touch off on each pin to ensure they are connected to the board properly. After you finish one side do the same to the other side of the chip. After all 22 solder points have been secured to the board, pull out your handy-dandy multimeter and switch it to the ohm setting. Verify that all points are properly connected.

Step 4: Solder on Antenna Connector (H9161CT-ND)
Below is the orientation that this connector should be soldered on. It is a pretty self-explanatory. As for the soldering it is done pretty much the same way as the GPS Chip. Flux the edges of the antenna connector and re-flux the area where the antenna goes. With a bit of solder on the end of the iron, tap each point and watch the solder flow onto the connector. After done, verify that points are connected with your multimeter. All three of the blue points are ground and the yellow is hot.

Step 5: Solder on Ferrite Bead (445-2171-1-ND - Or whatever ferrite bead you choose)
So what exactly is a ferrite bead? This small component blocks any "bad" signals coming back from the antenna due to the antenna being powered. This part is tougher to solder on because it is ridiculously small. Again like the other solder points, re-flux the points being solder. Using a tweezers (trust me, you need them) hold the chip in place and solder down one end quickly. After the end is soldered down push down on the top of the chip with the tweezers and solder the other end. If all goes well, this should stick fine. In the picture below the yellow represents where the chip will be sitting once solder in. It is in location (L11). Once the chip is in, use your multimeter to test the chip. On the picture touch your multimeter to the two blue dots. If you have a connection with no resistance (or very little) you should be fine. If you do not have a connection, go back and re-solder.

Step 6: Solder in 5vdc VCC Regulator (NCP551SN33T1GOSCT-ND)
This chip directly controls the GPS turning on and off when you enter a program like "Google Maps" or "Google Navigation" on your tablet. This chip will save the battery life greatly, by shutting off the gps when you are not using it (very helpful ) Again, flux the area to be solder and flux the pins on the chip. Using tweezers set the chip in the correct location on the board (pretty hard to mess this up). Solder down 1 pin per side to hold the chip down the proceed to solder the last 3 pins. The 5 pins that need to be soldered down are marked in yellow.
Minus the jumper here is what yours should look like so far:

Step 7:̶ ̶S̶o̶l̶d̶e̶r̶ ̶i̶n̶ ̶3̶.̶3̶v̶d̶c̶ ̶B̶k̶p̶b̶a̶t̶t̶ ̶R̶e̶g̶u̶l̶a̶t̶o̶r̶ ̶(̶M̶C̶P̶1̶7̶0̶0̶T̶1̶8̶0̶2̶E̶T̶T̶C̶T̶-̶N̶D̶)̶
This chip provides power to pin 11 of the GPS chip. It is used for a "Backup Battery" power supply. Apparently there is no battery but for the chip to work, this still needs power. Now this component is not required. Proper function of VBACKUP can be achieved by just using a jumper. As seen in the above picture I am using a jumper. The picture below on the left shows the 3 points to solder to put the chip in. The picture below on the right shows the location to jumper. Just use a small piece of wire to complete jumper circuit. On a side note: I did try to put in this chip but for some reason my tablet would not start up when I had it soldered in. I have no idea why (possibly a faulty chip?) Other people have looked over the chip datasheet and say it should work though so that's why I kept it in this tutorial.
EDIT Just use the jumper in this step. I have tried 2 different 3.3vdc chips in 2 different tablets now. It causes the tablet not to boot at all. Just jumper this location.

Step 8: Flip the mainboard over
I am not going to go into detail about how to do this because it's not too hard. I figure if you are inside of the tablet already you probably have an idea of how to do this Disconnect all wires from mainboard and unscrew all screws. There should be about 8 of them (screws). Once you do that pull the board out and set it on a level surface. Make sure you have yourself grounded because of static electricity. Once the board is out, flip it over and it should look somewhat like this.

Step 9: Locate and pre-solder last chip location
Just like you did on the front side, last chip location and presolder the 8 points for the chip and the 2 points for the jumper/resistor.

Step 10: Solder in Voltage Level Translator (296-21978-1-ND)
This chip is used to pass serial data from the GPS chip to the Tegra2 processor. If it is not in, the GPS will NOT be detected by the tablet. Using a tweezers put the chip in the correct orientation. (There should be writing on this chip, if you look at the chip directly below this location (U32) the writing should be in the same orientation [should line up]) Solder this chip in as you have the last few. At location R302 a jumper or resistor (P1.0KAGCT-ND) has to be added. This location is power for the "enable" pin on this chip. Use a wire for a jumper or the resistor. Test locations with multimeter to ensure proper connection (and so you do not have to remove your board again ) Here's what it should look like.
(ya ya ya, I know this soldering job looks like crap but it works right? )

Step 11: Optional LED Indicator Light
If you have been reading through this thread you will know that I installed an LED indicator light to show then my GPS chip had obtained a signal lock. This is easy to install. From pin 7 on the GPS chip run a wire and connect is to the positive lead on an LED. Attach the negative lead either to a ground location on the board, or even easier, just attach it under a screw on the case. Take a look at my picture to see how I hooked mine up. After the LED is in place drill a small hole through the top of your case so you can see it blinking even with the case backing on.

Step 12: Reassemble the tablet
At this point in the tutorial choose whether or not you want to use the antenna tutorial. If yes, jump to that tutorial if not...Reverse all steps for breaking down tablet. Put it back together and cross fingers while pushing power button (I would recommend making this antenna modification; the signal is much better)

Step 13: Go to the bottom of this page and read the portion entitled "Software Installation." It will give you the steps needed to get things working software side.


Official Antenna Tutorial:

The antenna is a critical component of this project because it is tough to sometimes get a satellite lock with the back case on. For those of you who have been following this project the other location for the antenna works but not as well. I would recommend this spot if you are installing this into your system.

Step 0: Please remember where things came from, screws, wires, etc. It will make your life much easier. Not all of my pictures will be able to explain where things are supposed to go back to.

Step 1: Take motherboard and battery completely out of tablet.
After this is done, your table should look like the following. (for some reason my tablet looked a bit different when opened up, but you get the gist)

Step 2: Remove metal bracket
This part is easy, just make sure the cords are out of the way. Just remove approx. 8 screws from the frame and it just lifts right off. Here is a pic of what it should then look like.

Step 3: This is where things get interesting.
At the top of the bottom section there is a screw hole which has to be removed. You can use any method of removal that you want but here is what I did. First take a screwdriver and pry the metal "screw thread" out of the plastic housing around it. Next use a pair of needle nose pliers to pull up as much plastic that was holding the "screw thread" in as possible. To finish it off use a razor blade to cut flush, the rest of where the "screw thread" was located. It's kinda hard to put this in words but pictures should do this justice.
(This is the completed image)

Step 4: Modify metal bracket.
This part is actually pretty easy and may not even be required. I only did it to gain as much space for the antenna to do its job as possible. I would recommend doing this. As you can see in the "before and after" pictures below a tab on the bracket needs to be ground off. This tab was not screwed into my tablet in any such way, so it's not like it mattered. To remove the tab get creative . I used a grinding wheel, but I'm sure that you could use a hacksaw or any other method. Take a look at the below pics and you'll understand better

Before:

After:

Step 5: Put the GPS antenna in.
Put the GPS antenna in the location that you just cleared out. You will have to remove a corner of the foam that is holding the camera down (not really a big deal). Put the chip in and if you choose you can secure an edge using any method of your choosing (just so it doesn't move) I used a tiny piece of sticky tack. Look at a few of the images below to figure out antenna orientation. It is pretty easy to see.

Step 6: Put it back together.
Reverse everything that you just did taking it apart. If you did it properly, you should have an antenna mounted as pictured below. It gets better reception and is probably the best location in the tablet for this antenna.

I hope that this helps out those who are having trouble finding a "good" location for their antennas. Post any questions that you have about this. I would be glad to help you out.

Battery Use:

• The tablet gets about 8 hours and 5 minutes of battery life while in a GPS application (pretty solid time!). The entire time the screen was on and the satellites were locked. I did turn wi-fi off during this test. Since this will be used during driving I did not feel like wi-fi was necessary to be turned on. If someone else wants to post results with wi-fi enabled, be my guest. I will update accordingly.

Data Connection:

• This is kind of a bummer when it comes to this tablet. Since the G-Tablet does not have a 3G card built into it, programs like "Google Maps" and "Google Navigation" have issues working. These programs need an Active Data Connection and since the G-Tablet only has WI-FI these programs do not operate like they should. The good news is that there are other programs out there that do not need an active data connection to operate. I am currently using a program called CoPilot Live 8. This program relies on pre-stored maps in the tablet to run. It works very well and I would recommend it for use on the G-Tablet. Here is a link to the software page. http://www.alk.com/copilot/

ROMS Tested

• GPS is now fully functional in all latest Android distributions (Froyo, Gingerbread & Honeycomb)
• VEGAn-Tab 5.1.1 (1.1 based ROM) - Works
• GtabComb - Works
• Flashback - Works
• CyanogenMod 7.1.x - Works
• All of the above I personally tried
• Brillant Corners 1.2.1 (1.2 based ROM) - Works
• MrGuy over at TabletRoms re-coded and released source code for "libgps.so" which is now "gps.harmony.so" in Gingerbread and Honeycomb. Rajeevvp took his latest file and ported it to the G-Tablet. If you are on Honeycomb and want to mess around with it here is the installer link to get GPS working on HC. (This method is more for developers that want source code to see how things work) If anyone wants to dig deeper into how the Honeycomb GPS works here is a link to the source code that MrGuy released. For the average user just stick to the following post on how to install GPS normally.

Software Installation

• Rajeevvp put together an "update.zip" for all firmware distributions. To use visit the following page and select the firmware version that you have (froyo, gingerbread or honeycomb). Install the "update.zip" via ClockworkMod like you would install any other updates. The "update.zip patches your current install files to enable GPS functionality. After install reboot your tablet and enjoy native GPS. If rajeevvp posts any updated versions of installers, he will always add the new ones to the above post.

Thanks: Special thanks for the following users twistedrotors and rajeevvp. Without their help this project would not be close to finished.

jmdearras said:

Oh, and add to step 1, UNPLUG THE BATTERY!

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Haha totally good call, I was totally gonna do this and I forgot.

clemsyn said:

Wish I had soldering skills like you guys

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haha, honestly I don't have much for soldering skills. I knew very little before attempting this project

tgruendler said:

Congratz on getting on Engadget with your writeup!!!!!!

http://www.engadget.com/2011/05/25/add-gps-to-your-viewsonic-g-tablet-and-test-your-soldering-skill/

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I'm pumped that we made Engadget!!!!

-+Bert+- said:

Great job guys! Do you plan to restore the mini PCI slot?

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Ha, most likely not on this one. I guess there are not that many devices that support a slot like this aside from a 3G card. I do not want to pay monthly fees for my tablet so I'm skipping the whole 3G thing.

dzasta said:

wow i totally forgot about this thread until I found it on engadget!

i have to give you credit fosser2 for diving in head first. glad there were no bga's to install. this is certainly something I will do in the future.

a couple of things: all of the "optional" caps you mention should be put down. the 0.1uf and 1.0uf caps are all decoupling caps used to regulate voltages and reduce noise. who knows, maybe Gmaps and Gearth will work?

as for the 1K resistor you shorted out, it can be one of 3 things. a series resistor to limit current, a pull up resistor, or a pull down resistor. Chances are its one of the later two. Its not the end of the world to short an I/O pin to Vcc or GND but it is not common practice and tends to lead to long term chip reliability issues.

after all of soldering youve done, whats a couple more 0402 placements? (OK the 0201's aren't going to be fun but still).

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Google maps works fine, I have not tried google earth but I'm sure that works fine too. As for that resistor I'll look into it. Thanks for the heads up.

Darth Bagel said:

I suggest a current limiting resistor in series with your lock indicator LED.

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The output of the lock line is outputting a very small voltage, why is a resistor necessary here? Sorry, I'm just wondering.