yashsingh1/xdaforums huggingface dataset:
[G Tablet General] fosser2:
I did find pics of the z-tab but I'm guessing that they are not what you want...But here you go anyways. I'm hoping you can pull some type of info from them.

zTab Pics.
[G Tablet General] twistedrotors:
Yeah, I saw those. And they just raise more questions! Lol! Everyone says the Ztab and Gtab are identical but obviously they aren't. It looks like the same GPS module would be used but the layout of the board is different. Oh well, no worries, we'll figure it out. :D

-John
[G Tablet General] fosser2:
I messaged roebeet again this morning. Heres what I said.

He replied.

If he does put the script back into the new version of Brilliant Corners, we might be able to properly get it enabled if it is truly software effecting the proper initiation of the pins.
[G Tablet General] fosser2:
I do have one other question, I want to make sure that I hooked up my antenna connector the proper way. All three of the circled contacts in the picture below go to ground. Does the antenna connecter have to be soldiered to all 3 of these pins as well as the antenna in line, or could a person just solder the antenna connector to one of the ground pins and one point to the hot.

Here is what the bottom of the antenna connector looks like.

The top pin is what connects to the antenna in line is what I got out of it. Correct me if I'm wrong. The other 3 "grounds" possibly get soldiered to the 3 ground pins.
[G Tablet General] twistedrotors:
As long as one ground pin of the connector is soldered to one ground pin on the pcb and the center antenna pin is soldered correctly (make sure it's not touching ground) then it should work just fine.

-John
[G Tablet General] twistedrotors:
Hey, how about replacing the cable with a longer one? Could try soldering on one of these. http://search.digikey.com/scripts/DkSearch/dksus.dll?Detail&name=J10037-ND

-John
[G Tablet General] fosser2:
give me a few mins, i'll post a few "possible" positions that the antenna could fit without extending the cord.

Pictures:
[G Tablet General] rajeevvp:
Excellent! Splendid! Most satisfactory. Because, if you look inside /system/lib/libgps.so, which is what, I think, the Java apps are ultimately using to get the location, we see:

$ strings /system/lib/libgps.so

[I]lots of crud[/I]

/dev/ttyHS3

[I]more crud[/I]

/dev/input/ [I]Hmm, close. Should have been /dev/input/event3[/I]

[I]more junk[/I]

/sys/devices/platform/gps_control/enable

[I]junk[/I]

Looks like we'll have to keep an eye on /dev/ttyHS3 from now on.

John, can you (re)attach the GPS module to your PC or Arduino board and send me the data that it spits out, along with the exact serial port settings--baud rate, stop bits, parity, etc? I want to have a look at the data and try a few tests here. The more GPS data you can send me, the better.

OK, this is not germane to the thread, but, since you guys have opened up your tablets...

Can you tell me what type of card the internal SD card is? Mine seems to be an MMC-type SD card. Another user I was talking to on the board had a kernel output which seemed to suggest that the user had an SDHC-type card.

I'm trying to find out if Viewsonic ships a device called the gTablet, but has slightly different hardware inside each. So, can you guys do a fresh reboot of the tablet and then send me the output of the "dmesg" command? I want to compare the kernel messages.

$ dmesg > /mnt/sdcard/dmesg.txt

or

adb shell dmesg > dmesg.txt

Thanks.
[G Tablet General] fosser2:
I'll post what I get when I get home in 3/4 hrs. I'll edit this post. Thanks for the software update!

Here's what I got. Just download the text file.

Hope this is what you're looking for!
[G Tablet General] twistedrotors:
Not a problem at all. I'm really glad you're on board with this project! Will send file through PM. GPS comms are 9600, 8, N, 1.

The chip on the back of my board is a Samsung KLMAG4EEHM-B101. According to this site it's a http://www.samsung.com/global/business/semiconductor/products/fusionmemory/Products_MoviNAND.html a MMC type chip and a "customer sample". Lol!

dmesg.txt file sent through PM.

-John
[G Tablet General] twistedrotors:
That antenna looks like it will fit well in the case. It's smaller than I thought it would be. I really think you could swap out that cable for a longer one but if it works well in one of those other locations then I guess you really wouldn't need to.

-John
[G Tablet General] rajeevvp:
Do you have any info re: the communication protocol used with the GPS module? Do you have to, for instance, send a command string to get it to start or stop sending the GPS co-ords? Or does it just keep spitting the stuff out as soon as it is enabled electrically? What's the frequency of the co-ordinate update?

That looks like the same chip I have, according to the kernel messages, but, another board member here has a different internal SD card type: a SE16G 14.8 GiB, instead of the standard, MAG4EM 14.9 GiB.
[G Tablet General] twistedrotors:
The module spits out GPS data as soon as it gets 3.3vdc. The data is sent out on its UART I/O port every 1 second. No start or stop command is necessary. There is both a TX and RX pin. TX has the GPS output data on it and RX can be used for config settings and firmware upgrades. I have not needed to change any settings (baud rate, etc.) so my RX pin is not hooked up. The data output is in NMEA output protocol V.3.00 (I'm not sure what this means, I just pulled it from the data sheet).

I am using an Arduino (with the microcontroller removed) as a serial UART->USB adapter and power supply for the module.

My module is pretty similar to Fossers, the big exception is that mine has an integrated antenna. The output data and voltage levels all appear to be virtually identical between our two modules.

This is fun! :D

-John

P.S. - Here's the link to the module I have, if anyone finds this interesting. http://www.cutedigi.com/product_info.php?cPath=248&products_id=4289
[G Tablet General] rajeevvp:
Thanks, that's helpful information.

About that internal SD card: was it soldered onto the board as a chip, or was it in a slot as a removable microSDHC card?
[G Tablet General] rajeevvp:
Decided to turn in for the night, but, then got up to check this, and... isn't this interesting:

John, do you have this pin connected to the board too? And, does it power on or off the GPS module when you toggle the GPS GPIO pins using the echo command?
[G Tablet General] twistedrotors:
For my setup I wanted the GPS module to always be on and always spitting out GPS data so that I wouldn't have to worry if the module was enabled or not. I went ahead and tied it to ground permanently (the green wire in the picture of my GPS module). But your question did get me thinking....

In my previous testing I noticed that U28 (the main power supply for the onboard GPS module) was always getting 5vdc on it's input. Normally this would mean that the GPS module would always be powered and draining our battery. But U28 also has an enable pin.

So after a little more poking around with my multimeter I figured out that when gps_control enable=1 then the enable pin of U28 receives 1.8v, a high. And when gps_control enable=0 then the enable pin is grounded. A quick check of the U28 datasheet and this looks good. A high on it's enable pin will in fact turn U28 on and a low will turn it off.

So, Fosser, did you happen to purchase a U28 when you ordered your GPS module from Digikey? :D

-John
[G Tablet General] fosser2:
Well the rest of the parts came today. Here is what I have done.

I have tested all pins and it is all soldered in correctly. I guess its just down to getting it enabled now...

The other 2 parts that I bought and haven't used are:

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

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

Is one of these the chip that you need John?

Looking back through the datasheet it does in fact look like I have this chip on hand! hooray! :p tell me where to put it in and I'll get it soldered.
[G Tablet General] fosser2:
Another thing that I have discovered. Pin 17 on my chip is a VOUT. It is supposed to provide the antenna with 2.85V Linear regulator power output. Even while my tablet is powered on, I am getting no voltage out of this pin. The active antenna needs this voltage to function.
[G Tablet General] fosser2:
I got antsy and decided to put the U28 in where I thought it went. Heres the pic.

John, let me know what you want me to try with it in.
[G Tablet General] fosser2:
sorry for all these different posts, but I feel like I should be posting new posts other than doing an edit. I was able to get my chip to power on. I was reading back through the gps datasheet and totally forgot to attach a power source to the VBACKUP. This is needed to be connected to run. My VOUT is now producing the proper voltage to power the antenna. Using the multimeter it is tough to determine if the chip has locked any satellites via the lock indicator pin. One of you guys with more knowledge than me should let me know what you think.
[G Tablet General] twistedrotors:
The progress continues!

U28 is the 5 pin regulator. Digikey part #NCP551SN33T1GOSCT-ND (http://search.digikey.com/scripts/DkSearch/dksus.dll?Detail&name=NCP551SN33T1GOSCT-ND).

If you have it soldered in then you need to remove that blue wire. What you have with it connected are two different regulators feeding voltage to the same pin. It's not the end of the world but it's not good for the electronics.

Where did you get your voltage for Vbackup?

Also, did you miss my previous post about the additional missing electronics? U34 (on the underside of the mainboard) is a voltage level translator and without it installed the data from the GPS module will never reach the main CPU. Page 5 has the info I discovered for U34.

-John
[G Tablet General] fosser2:
I'll pop that blue wire off right now and tell you whats up in a second. I pulled Vbackup from the pcie pin again :p (that again) and yes I did just read the post about the U34. About 15 min ago i ordered TXS0102DCTR and TXS0102DCUR. What chip do I have to use?
[G Tablet General] Zaphod-Beeblebrox:
I just want to tell you guys that I've been glued to this thread like you were announcing the winning lottery numbers on my ticket :)

If you guys get this figured out with a concise parts list and instructions, I will be very excited.

One quick question: I'm comfortable with using a soldering iron for some things, but haven't done a lot with PCB sized components. How difficult will it be for me to do the actualy chip ... did I read that it's BGA? I'm guessing I'll need to learn how to do that. That's done with flux and heat? not soldering each pin, etc?
[G Tablet General] fosser2:
JOHN YOU WERE TOTALLY RIGHT ABOUT THE BLUE WIRE!!! I pulled it off. I started up my tablet. No power to the gps. I enabled the chip via the echo command and presto! power to the chip!!! thanks a lot.
[G Tablet General] twistedrotors:
Cool! :D

Is 3.3v present on the PCIe pin even when the device is off? If so, should be fine. If not, you could just jumper across U22 like below. The yellow indicates what pins you would connect.

I've been looking at the TXS0102 datasheet and both DCTR and DCUR should work fine. I ordered both as well and Fedex says they'll be here tomorrow!

-John
[G Tablet General] twistedrotors:
Glad to have you here! So it looks like we have about 2 people following this thread now. ;)

The trick to soldering surface mount devices successfully is, in my opinion, practice. I've done a lot of SMD soldering and learning on a Gtab is not something I'd recommend. It isn't rocket science, really with practice I think anyone can do it, but burning up a Gtab is a real possibility here.

If you've never soldered SMD stuff before then check out this link and see if it helps put it in perspective. I love Sparkfun.com! :D

http://www.sparkfun.com/tutorials/36

-John
[G Tablet General] fosser2:
You are right the PCIe pin does not have power when turned off. I will jumper the U22 pin. I don't know when my FedEx parts are coming. I selected overnight shipping and the parts are coming tomm. Actually one of them got backordered so I will be recieving part TXS0102DCUR tomm. I'm hoping this is the one that we need for this project...
[G Tablet General] superchaos:
You guys have more than 2 peeps. I have been following also. Seems every non 3g tablet is missing something. Missing just one feature that would make a really cool tablet. Some are missing the camera or gps or wifi or have a crappy touch screen or slow processor. GPS would make this tab completely usable for me as wifi isn't necessary for mapping. Right now I can only use this thing for internet when a wifi is available. Nothing it can really do (by itself) from one location (home) to another (work).
[G Tablet General] fosser2:
Jumper pics:
[G Tablet General] bmasephol:
I have a feeling there are a lot of us lurkers waiting to see the what you guys are all able to figure out. I'd get involved but just don't have the time available at night to try anything out. Keep up the good work, I look forward to reading the thread updates!
[G Tablet General] dhanifin:
I've been following since the first post also. I'm a hardware guy and love seeing the progress and the synergy produced by a few motivated people with different strenghts.

Now that Roebeet left I don't read XDA nearly as much as I used to... So this thread is just about the reason I have to drop in.

Keep up the good work guys!
[G Tablet General] mike_ekim:
Another lurker

I guess I'm the type to read lots and seldom post, so just a FIY that I'm following and if you can pull this off I plan to do the same.
[G Tablet General] fosser2:
I soldered in TXS0102DCTR and got nothing...I'm pretty sure that I soldered it in right. I'm hoping it is in backwards...John let me know how yours goes.

EDIT: I possibly missed a pin after rechecking with the multimeter. I went back and re-soldered all pins. Here is a picture, John let me know if the orientation is correct.

I also need to know how long the gps takes to acquire satellites.
[G Tablet General] twistedrotors:
Cool, I'm glad people are enjoying this thread! I sure hope we get this working. :)

Fosser, looks good, that is the correct orientation. I just soldered in my TXS0102 as well and I'm about to test it out. Fingers are crossed!

The module can take up to 15 minutes if it has to download almanac data. Should take around 3-5 mins from a cold boot. Make sure it's got a REAL good view of the sky. My module is different but if it's not near a window then it takes a VERY long time to get a lock.

-John
[G Tablet General] fosser2:
well, mine looks like a no-go... I need another thought to get this train rolling again. It must be something small that I messed up, or something that we overlooked in the software side of things. :(
[G Tablet General] twistedrotors:
Got it! And apparently I'm in China! :D The light blue dot in southern China is where Maps says I am, the star over Houston is one of my saved locations. Now to figure out what's up with the miss-location. Maps must use NMEA data in a different format or something.

Nyingchi, Tibet, China....apparently. Lol!

To get you going Fosser, you need to jumper R302. It's located directly above U34. Apparently U34 also has an enable pin. Lol, took me a while to figure out what was wrong. Here's a pretty high-res pic of the U34 location. I have not jumpered R302 yet in this pic. BE VERY CAREFUL WHEN SOLDERING THERE! Too much heat and the pads will pull off the board! Good luck!

-John
[G Tablet General] fosser2:
AHHHH I can't wait to get back home and do this! Just gotta make it through this 90 question electricity final first... damn college :p

John - can you quick do me a favor and show me exactly what to jumper, I need to make sure I jumper the right location. Thanks a ton!
[G Tablet General] twistedrotors:
Good luck on your final! My last one was Wednesday, now I have 3 weeks of freedom!

So I did a little poking around and the coordinates that my GPS spits out for me are: 29.449877, 095.227816

If I search for 29.449877, -95.227816 in Google Maps it gives my general location. But if I put 29.449877, 95.227816 in then it shows me in China, just like my tab is doing. Fosser, I'm really curious what your location is going to be. I'm going to read up on NMEA sentences and see if there's a way to make my module spit out the right format.

-John
[G Tablet General] twistedrotors:
Done. No problem! Red indicates the two pins you should connect. You can use a piece of wire (I did) but if you happen to have a 1k ohm resistor that'll fit there then that would be the "proper" solution. Not that we've been too worried about what's the "proper" way to do anything for this project. Lol!
[G Tablet General] fosser2:
Well I jumpered those pins. Right now Maps still says location unavailable, navigation just sits at finding location also...I tried CoPilot Live Pro. In the location it did detect a satellite. But did nothing more from there. We're so close but I feel like I'm missing something. I am wondering if it has to do with the ferrite bead. I guess I hope that I'm using the right one.

Scratch that: It's doing something now that I rotated the antenna. I'll report back in just a bit.

-Right now I am pulling a latitude of 44.871322 (it is varying a bit)/Longitude of 91.921773E (it is varying a bit)
[G Tablet General] manikin13:
:cool:

Holy Cow!!!! I hope to follow in your footsteps closely, as I liked your solution of the antennae overs foss's.

Congratulations on making the gtab even a better value than it already was. I was using a bluetooth GPS, No need now.

THANKS for the hard work.
[G Tablet General] twistedrotors:
You are VERY close. If it found a satellite then that means the module is working and it may just be an issue with your antenna at this point. Double check your solder joints, make sure there are no shorts to ground. I'm heading out to dinner right now, but I'll keep thinking.

You wouldn't happen to have a spare LED laying around would you? You could tie one end of it to GND and touch the other to the LCKIND (pin 7) on your module and see what it does. LED's are directional, so if it doesn't light up one way, swap the pins. :p

From the datasheet: The Lock Indicator line outputs a series of 100mS pulses with a 50% duty cycle when the module is searching for a fix. Once the receiver acquires a solution, theline outputs a single 100mS pulse every second. This line can be connected to a microcontroller to monitor the state of the module or connected to an LED as a visual indicator.
[G Tablet General] fosser2:
my gps is pulling a location right outside of Mongolia. It has been consistently there. I even formatted user data and started from scratch.
[G Tablet General] scyld:
Just FYI to you all, I'm following your progress as well. Thank you all for working on this.

My experience in soldering is limited to big, bulky components like individual resistors and capacitors, where you just need a big old soldering iron, and ugly large blobs of solder often are good enough (I personally try to make things clean if I can).

I'll try to go over things from the beginning to see if I can get a coherent flow to the development process sorted in my head, but soldering SMD's look terrifying though feasible. I think I might stick with an external Bluetooth GPS receiver if I have to, though it sucks the company couldn't just chip in a little more money to increase their product's desirability 10x.
[G Tablet General] twistedrotors:
Well we're not out of the woods yet, but we're gettin' close!!

Outstanding! This has got to be some sort of config issue now. Where's our resident software guru!?!?! Rajeevvp we need you!! :D

It's definitely not a mod for the faint of heart. Some serious damage could be done to the tablet if you're not careful. Not trying to discourage anybody, just throwin' that out there. :p

-John
[G Tablet General] fosser2:
Please, Please come back! lol totally second this!
[G Tablet General] twistedrotors:
Looks like the Notion Ink Adam has the same issue.

http://xdaforums.com/showthread.php?t=932887

I tried making my own gps.conf file with the info from that thread and sticking it in /system/etc but it didn't change anything. Longitude is still inverted.

-John

Edit: Correct location is shown using a modified version of Maverick for the Notion Ink Adam, available here. http://notioninkhacks.com/forums/viewtopic.php?f=18&t=470 Search continues.
[G Tablet General] jmdearras:
On the reasonable assumption this can be fixed, is there a definitive parts list available for others (me!) to order and install. I am not concerned about smd soldering, been doing it for decades.

Thanks,

Jim
[G Tablet General] fosser2:
I will put together a list for you quick. Give me just a sec.

Part List:

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

http://search.digikey.com/scripts/DkSearch/dksus.dll?Detail&name=H9161CT-ND

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

http://search.digikey.com/scripts/DkSearch/dksus.dll?lang=en&site=US&KeyWords=RXM-GPS-SG-B&x=0&y=0

http://search.digikey.com/scripts/DkSearch/dksus.dll?Detail&name=445-2171-1-ND (still may be issues w/ this but is dirt cheap so w/e)

http://focus.ti.com/docs/prod/folders/print/txs0102.html

That about sums it up. The last product you can get for free and also have free overnight shipping :p

I assume if you only need a part list you have been following this thread for awhile and you know whats going. I hope this helps you out.
[G Tablet General] fosser2:
I feel like this is needed to be said at the point that we're at.

I WILL BE MAKING A TUTORIAL ON HOW TO DO THIS

. We are not yet finished with this project yet but are making headway. Please don't ask for a tutorial just yet. If you have been following this thread there is enough information to get to the point that we are at right now.

Yes the program of Maverick is properly working! it pulled my location perfectly!

(I really wish I had a camera and not a buncha cell phones :p)
[G Tablet General] Vlad_z:
Guys, who got gps working but with inverted Longitude.

Can you do hexdump of your gps data (as you have tried before ). Let's see what's raw NMEA protocol looks like.

As far as I remember the command are :

# hexdump -C /dev/input/event3
[G Tablet General] fosser2:
I'd do it right now but i dont have time...gotta hit some grad parties :p I'll try and check on this thread later.
[G Tablet General] manikin13:
With adb you can do actual screen prints using ddms.
[G Tablet General] jmdearras:
I bet they are ignoring the E/W and N/S indicators in the NEMA stream. Anyone south of the equator in a position to verify this?

Jim
[G Tablet General] jmdearras:
I'm just trying to get my parts together with reasonable shipping costs. I might be able to help, even, I have several patents on hand held embedded systems.
[G Tablet General] jmdearras:
GLL – Geographic Position – Latitude / Longitude

The table below contains the values for the following example:

$GPGLL,2503.6319,N,12136.0099,E,053740.000,A,A*52

Name Example Units Description

Message ID $GPGLL GLL protocol header

Latitude 2503.6319 ddmm.mmmm

N/S indicator N N=north or S=south

Longitude 12136.0099 dddmm.mmmm

E/W indicator E E=east or W=west

UTC Time 053740 hhmmss.sss

Status A A=data valid or V=data not valid

Mode A A=autonomous, D=DGPS

Checksum *52

<CR> <LF> End of message terminator
[G Tablet General] superchaos:
Does it matter what ROM is installed?

I have VEGAn 5.1.1 Not sure if the Maverick Pro apk will work or if the rom will pick up the GPS hardware. Will it matter? What ROM are the founders using?