Controller board for capacitive touch panel

[hQamonky]

Hi there,

I'm new to the forum so sorry if I misplaced this thread.

I own an Android tablet which is broken, but the LCD screen and touch panel are unharmed.
I would like to use those to build a touch monitor for my PC or Android phone. I managed to find an LCD controller which should work for the LCD panel, but I don't know how to get the touch panel to input signal through USB.
I searched on google with lots of different keywords I could think of but I didn't find anything with the correct connector for the touch panel (in fact I don't even know if it exists).


Does annyone how I can plug a device to this touch panel by USB ?

 

[d123]

Hi.
Without seeing it, guessing that you may mean a transparent orange ribbon cable type of connection, maybe what you mean is an FPC connector. I'm no expert, but that sounds pretty hard to convert to USB thinking of the number of contacts/pins needed, which doesn't mean to say there isn't an adapter cable in existance.

If you want to, try these links to see if it's the connector you're referring to by the images and the catalogue section:

https://www.bing.com/images/search?q=fpc+connector&qpvt=fpc+connector&qpvt=fpc+connector&FORM=IGRE

https://uk.rs-online.com/web/c/connectors/pcb-connectors/fpc-connectors/?searchTerm=LCD+TFT+connector

- - - Updated - - -

...more links, in case they are of use to you in finding what you're looking for:

Image 4 shows the whole set-up...
https://proto-pic.co.uk/40-pin-tft-friend-fpc-breakout-with-led-backlight-driver/

A breakout board if you want to figure out the interface wiring and solder the connector...
https://proto-pic.co.uk/50-pin-0-5mm-pitch-fpc-adapter/

LVDS is another type of connector used for LCDs...
https://uk.rs-online.com/web/c/connectors/pcb-connectors/lvds-connectors/?searchTerm=lcd+cable

This cable appears to be for a computer, so not much use, but perhaps there is something similar for LCD touch displays...
https://www.memory4less.com/m4l_itemdetail.aspx?itemid=1475453578&partno=V000949060&rid=26

...couldn't find any solid image or link to a product/device of a USB to FPC LCT TFT adapter cable whilst searching, except for the Toshiba FPC to USB motherboard cable. Mobile phone, industrial monitor or e.g. car GPS component suppliers/manufacturers may have something or some practical advice. The Adafruit "40-pin TFT Friend - FPC Breakout with LED Backlight Driver" was the best thing I found for your Arduino, but it's not USB, so best of luck.

 

[d123]

Again, not USB, but it is for Arduino and "display modules", so if this one is no help due to incompatibility issues a version may/should/must exist for whatever brand your LCD TFT is:

"The 4D Arduino Adaptor Shield (4Display-AdaptorShield) is a simple Arduino Shield designed to provide a convenient interface to attach 4D Systems display modules to the Arduino platform, without having to use jumper wires on the Arduino headers."

https://www.4dsystems.com.au/product/4D_Arduino_Adaptor_Shield_II/

 

[hQamonky]

Thanks for your answer,

I was actually thinking of a board which converts the touch into USB (like an Analog-to-Digital-Converter) rather than a simple cable. Like you said, it is an FPC cable and there are a lot more pins than in USB.
The links you send me seem to be going towards the right solution but I was hoping to find a board which is already built and programed, and just plug-and-play...
I don't think the adafruit adapter will work though because my FPC cable oddly seperates in two and I need to plug it into two seperate FPC connectors. Another problem is that I do not know how many pins my FPC cable has.
So if such a board doesn't exist, what I should do is: buy two right FPC connectors for my FPC cable, weld them to a board, connect it to an Arduino and find or create a program wich translates the signal transmited through the FPC cable and send it to the PC by USB ?
I have no idea if this is the way it works...

 

[d123]

I have no idea if this is the way it works...

- that's my honest answer too...!

Erm..., if it's not too much trouble, imagining you've already taken the tablet apart, could you post a photo of the double fpc cable and connectors where they connect to on the tablet (and the LCD end if you think it would help), and it's a good idea to say the model tablet/LCD, or failing the model tablet any identifying reference on the tablet main board and ideally the LCD or something similar if they have any, if you want to, otherwise it's just guessing rather than actually trying to give as informed an opinion as possible. For one reason, some-one here might spot a device on the board that will help to narrow down how to go about it.

Also, I don't want to bombard you with useless questions, but does the/do the fpc cables have numbers at each side next to the connector or anywhere along the cable, e.g. "1 40"? Is it possible to count the strips (or connector pins) to know how many contacts/cables are actually used?

To be honest with you, I hate to sound negative, I don't want to at all as your project sounds really fun and worthwhile, and surely is worth trying, but also it sounds very hard to do without locating the actual hardwares' datasheets/product info., etc. and in that way being able to put together what you want to with some idea of how this stuff works (before damaging the LCD, for example, which could happen if I tried to do this by guessing and connecting things anyway), unless you already know most of how these things work.

No idea if a touch to USB board exists, seems odd there aren't a few appearing in seach engine results as it is a fairly obvious need/handy device for more than a few people.

By weld I'm understanding you mean solder!

Sorry to ask, just "brainstorming" with you here - but do you reckon the "a board which is already built and programed" for plug-and-play may not be a definite option as perhaps this board and LCD were designed in-house to be very application specific for Android devices or for a board just for whoever manufactures the tablet?

I'm sorry I can't offer any practical advice, but do recommend posting a photo or two. Your idea described at the end could work, as I think you are clearly more versed in programming and these devices than I am (I only learnt the day before yesterday what apt-get means, and that was a big leap forward for me). By all means, if you know how to analyse the signals and translate them to appropriate signals for USB, then as you suggested get the connectors and solder them to a bit of pcb, but if it were me I think I'd do a bit more research first into the make and model of LCD and try to get hold of the manufacturer's datasheet.

Sorry, but don't forget the photos if you can upload a couple.

To end on a positive note, awwww - your screen is capacitative, mine is resistive, yours is supposedly better and more durable than mine

 

[hQamonky]

Yes solder is what I meant! (sorry I'm french).
I am an IT student so I have some programming knowledge and I've done a little bit of Arduino 2 years ago. I don't really know much in electronics and I don't know how to analyse and translate the signal, but I think I could manage if I have to (I have some idea how to do it).

I'll try to post as much information as possible :
- The tablet isn't really a tablet, it is the dock for Asus' "new padfone infinity (A86)": https://www.asus.com/Phone/The_new_PadFone_Infinity_A86/
The phone is broken so I'm left with the dock.
Yes this screen is very nice, it is 1920*1200 10.1 inch LCD and the touch panel has 10 touch points.

- This is what I'm trying to work with (13AT0031AP0501): **broken link removed**
I think I can connect and controle the LCD with this board: https://www.ebay.com/itm/M-NT68676-2A-HDMI-DVI-VGA-Audio-LCD-LED-Screen-Controller-Board-Diy-Monitor-Kit-/110977522562

- This is what I'm trying to connect and convert to USB(5363N FPC-1): https://www.alibaba.com/product-detail/10-1-for-Asus-PadFone-3_60136341501.html?spm=a2700.7724857.35.1.LbKHzG&pid=121219&cn=16426&cv=custom&tp1=0%3A%3A121219%3A%3Aea72478b958eef6241502b6ef17c55b3%3A%3A%3A%3A1441317710


Here are some pictures :

This is the whole thing:


Zoom on the labels :


Connection of the LCD and touch panel:


Other side of the FPC cable:


This is where the FPC connects into the tablet (the LCD connects on the other side of the board):



(edit: the links were not in the right order)

 

[FvM]

There's a huge number of different touch panels used in various devices, all using different FPC connectors and having different pin layout. So it's rather unlikely that you find a fitting touch controller with USB interface.

 

[hQamonky]

There's a huge number of different touch panels used in various devices, all using different FPC connectors and having different pin layout. So it's rather unlikely that you find a fitting touch controller with USB interface.

So the only solution would be to make a touch controller myself?

 

[FvM]

So the only solution would be to make a touch controller myself?

Probably yes. You can e.g. look at the Atmel maXTouch controller series. You'll notice that the design involves PCB layout with fine pitch BGA components and selecting the right FPC connector out of confusing large choice. That's demanding even for a professional design.

 

[d123]

Hi, sorry, didn't see you'd answered until now. Shame, the thought of some-one welding tiny components with an arc welder is kind of fun!

If you think you can connect the LCD to the LCD/LED Screen Controller Board Diy Monitor Kit, it's worth a try.

You're brave, that all looks really hard to put together and understand what signals the cables are sending and receiving. If you have some idea of how to do it, why not and good luck.

 

[hQamonky]

You can e.g. look at the Atmel maXTouch controller series.

I checked out the Atmel website, but it looks like it's only for companies, can I buy products as an individual? (not sure how to say that in english)
I also couldn't figure out the prices of their products.

 

[FvM]

There's probably an IP protection aspect that causes Atmel to restrict the amount of freely available information about the touch processors. But I guess, they simply can't a imagine that a hobbyist would start a project with these devices.

It might be expected that professional designers need an Atmel FAE sitting "on their lap" for a succesful project. As a side effect, the general support is unfortunately scarcely.

There are a few more companies in the capacitive touch market. But I'm not up-to-date with multi-touch products, I recently did a simple four-button design with NXP.

 

[d123]

Hi. If yours is a four-wire type, maybe the evm document could help as a reference to work around/with, maybe a look at the evaluation board for one (last two pages contain: "Schematic diagrams of the TSC2101EVM showing the TSC2101 connections and the USB and connectors are shown on the following pages." will or won't be useful to you.

Touchscreen controllers:
https://www.ti.com/paramsearch/docs/parametricsearch.tsp?uiTemplateId=APP_PARAM_T&appId=209&filter=p1498|EQ|Automotive&familyId=636&family=analog&automotive=true&paramCriteria=no&keyMatch=touchscreen controller capacitive&tisearch=Search-EN-Products#columnOrderString=o1,o4,p1103,p1105max,p595,p1498,p1192,p2954,p1811,p1130,p1341,p1067,p776

TSC2101 Touch Screen Controller, Evaluation Module:
https://www.ti.com/lit/ug/slau112a/slau112a.pdf

Can you register as a user with Atmel?, there's sometimes more info. available to registered users with some of the tech websites.

 

[hQamonky]

Hi. If yours is a four-wire type, maybe the evm document could help as a reference to work around/with, maybe a look at the evaluation board for one (last two pages contain: "Schematic diagrams of the TSC2101EVM showing the TSC2101 connections and the USB and connectors are shown on the following pages." will or won't be useful to you.

No it's not a 4 wire type.

Can you register as a user with Atmel?, there's sometimes more info. available to registered users with some of the tech websites.

I did register but nothing changed unfortunately.

 

[d123]

Shame about the website, sorry there. So what type of touchscreen is it?
I ask as I'm curious and was just reading the controller IC datasheet used in the device I got recently (I may as read what ICs and other devices it's made from and learn something), and it says you can configure the IC for 4, 5 or 8 wire displays, and has 10 bit resolution, and looks easy for some-one with programming experience to configure. That's a Microchip Tecnologies part.
Another pathetic suggestion I have is: Can you actually visibly identify the touch controller IC on the broken phone (with a magnifying glass probably)? That might save a lot of reverse engineering and so on.

 

[FvM]

So what type of touchscreen is it?

You can safely assume that it's a recent multi-touch device, suggestes both by the wide FPC cable and the required functionality of a tablet computer. So simple touch controllers like the TI types won't work for it.

 

[d123]

Right, thanks for that. What does "ten touch points" mean, is it the same as 10 bit resolution?

 

[d123]

Hi hQamonky, hope it's going well. Looking for simple projects for myself this morning I also found a link to LVDS adapter boards and cables, here are the links in case they are of use to you:

This has a double ribbon cable connector (i.e. two connectors) on the adapter board, I can't see from your photos if both cables are the same size or one is a bit wider, which they are on this adapter board:
**broken link removed**

Sadly, this one says the seller withdrew the the device, but I'm adding the link as it might be a way to find the right board,
"1Pcs LVDS 20 pin To TTL Dual 30 Pin Adapter Converter Board" (the picture of the board of interest is bottom left on the page):
**broken link removed**

"How to use HDMI-dualLVDS converter" - the connector is wrong, but it has a pinout table of the LVDS connector connections/functions, and this company (Chalkboard Electronics) specifically sell 10" capacitative touchscreens and adapter boards to hobbyist's (some guy connected a 10" screen maybe like yours to a Raspberrry Pi with the adapter board - and I know Pi and Arduino are different), and the website says you can buy "discontinued products" by e-mailing them:
https://www.chalk-elec.com/?p=2109

Systemation have a selection of adapter boards too:
https://www.systemation-inc.com/index.php/products/drivers/single-use-adapters

Best regards

 

[hQamonky]

Both connectors on the cable are the same size unfortunatly...
I tryed to count the pins on the connector and I think there is 20 pins on each connector.
LVDS is a connection which transports the image for the LCD and the touch inputs in the same cable?

 

[d123]

Hi. Another "near-miss"! - there must be an adapter board for that cable somewhere... Thanks, so it has 20 + 20, that helps to narrow/limit any future incorrect links to something marginally less wrong! Sorry, I'm trying to help and failing badly here.

LVDS, image and touch over one cable - maybe, maybe not, I imagine it can/does (maybe not the touchscreen/phone 'though) as everything is just a 1 or a 0/on or off/high or low at the end of the day, no matter what the data or how the signal(s) travel from A to B, by rising or falling edge, or if they are multiplexed or not, etc.
You may as well look at the Wikipedia (or other source's) definition of LVDS, otherwise I'm just being a pseudo-knowledgeable parrot, and also because you may see something of interest there that I'll overlook. From what I read, LVDS is a high speed, low power "serial communications protocol" that is used in multiple applications, "such as LCD-TVs".

More links (don't shoot the messenger):

The phone "Video out: 1920x1080 (1080p) FHD resolution USB Series Micro-B (Micro-USB) with SlimPort (MyDP) connector " - Is that how the phone and tablet connect/dock, or by USB?:
http://pdadb.net/index.php?m=specs&id=5018&view=1&c=asus_padfone_infinity_2_a86_32gb

SlimPort (DisplayPort):
http://en.wikipedia.org/wiki/DisplayPort

If you have curiosity and time for 94 pages - "LVDS Owners Manual" - National Semiconductor (now part of Texas Instruments):
http://forums.xilinx.com/xlnx/attachments/xlnx/Spartan/2848/1/LVDS.pdf

FDP-Link (relates to LVDS):
http://en.wikipedia.org/wiki/FPD-Link

"Application Note 1127 LVDS Display Interface (LDI) TFT Data Mapping for Interoperability with FPD-Link" - Texas Instruments:
**broken link removed**

"Low-voltage Differential Signaling (LVDS) Design Note" - Texas Instruments:
http://www.ti.com/lit/an/slla014a/slla014a.pdf

I'll go back to my researching useless links for a while, and failing to write really basic Linux commands correctly later... I hope you've managed to find something useful for your device.

Regards!