Author Topic: LVDS 18.4" with Touch Screen (resistive) - FULL HD  (Read 6715 times)

Offline @lex

  • Full Member
  • ***
  • Posts: 157
  • Karma: +4/-0
    • View Profile
LVDS 18.4" with Touch Screen (resistive) - FULL HD
« on: January 18, 2015, 06:22:26 pm »
Hi,

This is a project i started working, which has  a 18.4" LCD panel with Resistive touch and Full HD (1920x1080), pushing the CB2 and allwinner A20 to its limits.

There are some issues i am working on.

I would like to thanks George Ioakimedes for helping with the LCD Panel and finding the correct timings.

I will get this working with X-Org and share my findings if i can.

Here is the woking in progress:
https://drive.google.com/file/d/0B7A7OPBC-aN7bFFURkdLVkZGckk/view?usp=sharing

@lex

Offline @lex

  • Full Member
  • ***
  • Posts: 157
  • Karma: +4/-0
    • View Profile

Offline shineworld

  • Newbie
  • *
  • Posts: 24
  • Karma: +0/-0
    • View Profile
Re: LVDS 18.4" with Touch Screen (resistive) - FULL HD
« Reply #2 on: March 02, 2015, 05:37:24 am »
I've tried A10/20 on chip TS module with 10"/12" displays but in my experience sensibility IS TERRIBLE.
Very high noise also modifing SOC settings and placing heavy filtering....

What is your experience ?

Offline @lex

  • Full Member
  • ***
  • Posts: 157
  • Karma: +4/-0
    • View Profile
Re: LVDS 18.4" with Touch Screen (resistive) - FULL HD
« Reply #3 on: March 02, 2015, 02:22:47 pm »
I received my first 15.6" TS panel one year ago and it took me 6 months to get it working the way you described, lots of noise, sensitivity not so good. I was about to give-up but learned i could pass some parms to the TS hardware to minimize noise and sensitivity and by trial and error i achieved reasonable results, so i ordered a new one from the same supplier.

I got a different one, slightly larger, that was i suppose from another manufacturer and guess what, it worked like a charm, very pleasant, similar to my cheap android phone with capacitive touch (yes, the one i took the blurry video, i dropped it and i think the camera detached from the gorilla glass..).

I know now the first panel was good for shooting target, a trash.  :o

So not all resistive TS are made equal.

This 18.5" TS panel were taken from an older poker machine, just to be sure it would work and as a proof of concept and for the prototype. This one is also good for...cof,cof, mirroring.  ;D

The only thing i know for sure is that the error, the noise and the sensitivity increase with size, perhaps the usb module has some very cleaver algorithm to minimize it.

Finding a good resistive TS is the key.

Offline @lex

  • Full Member
  • ***
  • Posts: 157
  • Karma: +4/-0
    • View Profile
Re: LVDS 18.4" with Touch Screen (resistive) - FULL HD
« Reply #4 on: April 06, 2015, 05:02:48 pm »
Just to keep you informed about the Xorg TS integration.
I have Lubuntu 14.04.2 working with Resistive TS as you can see on the video below if you are interested.

There are minor issues to be solved:

Quote
* double click does not work, perhaps due to noise/error propagation on this old TS or that Ubuntu (me as well) don't know how to trigger it in Xorg.
Any suggestion would be appreciated.
works with a workaround now but limited by TS quality, not really usable.

* dragging is not a good experience yet. I think it could be solved with new panel (accepting donations  :) ).

I will provide instructions on how to get this working.

You can see some work here:
https://drive.google.com/file/d/0B7A7OPBC-aN7dld1UFgtQTBicjQ/view?usp=sharing

https://drive.google.com/file/d/0B7A7OPBC-aN7ZUxHT04xcEJicjQ/view?usp=sharing

@lex

PS: writing and collecting info at the moment.
« Last Edit: April 11, 2015, 12:39:47 pm by @lex »

Offline mborras

  • Newbie
  • *
  • Posts: 13
  • Karma: +0/-0
    • View Profile
Re: LVDS 18.4" with Touch Screen (resistive) - FULL HD
« Reply #5 on: May 28, 2015, 05:44:28 am »
Hi!

I'm trying to do the same you do in https://drive.google.com/file/d/0B7A7OPBC-aN7bFFURkdLVkZGckk/view . Can you give me some instructions to achieve that. I'm working with a cubie2 (android, kernel 3.4).

Thanks in advance.
Marc.

Offline @lex

  • Full Member
  • ***
  • Posts: 157
  • Karma: +4/-0
    • View Profile
Re: LVDS 18.4" with Touch Screen (resistive) - FULL HD
« Reply #6 on: May 29, 2015, 08:54:17 am »
This is for resistive panel, do the following:

* Enable the resistive touch, change the script.bin to:
[rtp_para]
rtp_used = 1

and disable capacitive one
[ctp_para]
ctp_used            = 0

For Android the XY pins are inverted,  if you touch the left side of the panel you get a right touch event instead, so switch the pins.

If you have capacitive ts, find the correct driver for your panel and change it to the correct driver name:
[ctp_para]
ctp_used            = 1
ctp_name            = "gt811"
ctp_twi_id          = 2
ctp_twi_addr        = 0x40
ctp_screen_max_x    = 1024
ctp_screen_max_y    = 600
ctp_revert_x_flag   = 0
ctp_revert_y_flag   = 0
ctp_exchange_x_y_flag = 1
ctp_firm         = 1

You may need to recompile the kernel driver or install the vendor driver.

Good luck.

* Note: Just a quick comparison Capacitor TS vs Resistor TS

Resistive TS panels have this advantages:
* are cheaper,
* have many sizes,
* are good for touch only,
* made of glass or plastic film

If you need precision, dragging and high sensitivity go for the capacitive
« Last Edit: May 31, 2015, 11:01:17 am by @lex »

Offline mborras

  • Newbie
  • *
  • Posts: 13
  • Karma: +0/-0
    • View Profile
Re: LVDS 18.4" with Touch Screen (resistive) - FULL HD
« Reply #7 on: June 04, 2015, 03:29:35 am »
Thanks for your reply @lex  :). I'll try it.

Offline @lex

  • Full Member
  • ***
  • Posts: 157
  • Karma: +4/-0
    • View Profile
Re: LVDS 18.4" with Touch Screen (resistive) - FULL HD
« Reply #8 on: June 04, 2015, 11:12:20 am »
You can take a peek at the work done with a capacitive ts here: https://drive.google.com/file/d/0B7A7OPBC-aN7a2FXTDEzVDF4NTg/view?usp=sharing

Offline mborras

  • Newbie
  • *
  • Posts: 13
  • Karma: +0/-0
    • View Profile
Re: LVDS 18.4" with Touch Screen (resistive) - FULL HD
« Reply #9 on: June 04, 2015, 11:41:09 am »
Thanks for the info @lex. But for a bigger screen (15 or 18.4") I have to do the same work? Doesn't matter the size if both use gt811?Am I right?

Offline @lex

  • Full Member
  • ***
  • Posts: 157
  • Karma: +4/-0
    • View Profile
Re: LVDS 18.4" with Touch Screen (resistive) - FULL HD
« Reply #10 on: June 04, 2015, 11:54:50 am »
You have to find the correct driver name, "gt811" is just one of many out there. It depends on the panel you will use. Look at the source code in SDK/BSP.

Size matters if you have to calibrate the TS, you have to adjust for the size of the Panel, that is: 800x480, 1366x720, 1920x1080 or any other size.

Offline mborras

  • Newbie
  • *
  • Posts: 13
  • Karma: +0/-0
    • View Profile
Re: LVDS 18.4" with Touch Screen (resistive) - FULL HD
« Reply #11 on: June 05, 2015, 02:05:52 am »
Thanks for all @lex !  :) :)

Offline mborras

  • Newbie
  • *
  • Posts: 13
  • Karma: +0/-0
    • View Profile
Re: LVDS 18.4" with Touch Screen (resistive) - FULL HD
« Reply #12 on: March 03, 2016, 03:43:09 am »
Hi again @lex!

Can you say me which is the touchscreen provider that sold you the touchscreen ?

Marc.