ebay 3,5" TFT With Touch

[maurosmartins]

Hello all,

I've recently bought one of these 3,5" TFT displays for use on a project. Unfortunately it was damaged during transportation and the touch panel itself was broken. I was able to use the rest of the display to start writing code for my application.

I've ordered a new display, and my question is; how do I read the touch panel, I haven't found any clue on how to read the touch information, what is the interface?

Thanks in advanced,
Best regards, Mauro.

[ebclr]

1st step is to identify the touch controller, then read that datasheet

https://www.mouser.com/Semiconductors/Data-Converter-ICs/Touch-Screen-Controllers/_/N-625wj?P=1yq2yc5

[maurosmartins]

Hello,

it doesn't help much, physically I can only see two extra ICs on the PCB (74HC245) not touch controllers.

any usual touch controller in these boards as the ILI9481 is for the TFT itself.

Best regards, Mauro.

[Mr. Scram]

I haven't had much luck with these. One broke before arrival and one developed spots shortly after.

[MasterT]

It could have resistive touch panel, use your multimeter in resistance measurement mode, check  across A1 - A2 and D6 -D7 (arduino pin mapping), 300-600 Ohm expected.

[msliva]

Hello,

I do not have this LCD but you can read the the sources bellow. Maybe could help.

You can try read the reviews on the bottom of the page: "Download MCUFRIEND_kbv library from gitub plug in and play, its simple"

https://www.ebay.com/itm/3-5-inch-TFT-LCD-Touch-Screen-Display-Module-480X320-fr-Arduino-UNO-Mega-2560-JS-/222772682548?_trksid=p2349526.m4383.l4275.c10#viTabs_0

https://github.com/prenticedavid/MCUFRIEND_kbv
https://forum.arduino.cc/index.php?topic=366304.0

[maurosmartins]

Hello all

thank you very much for your quick replies,

Yesterday I've unglued the display from the PCB reviling the touch panel pads, with a multi-meter on continuity I've searched the corresponding pins, they were just like the ebay comment that msliva has pointed.

YP = A2, XM = A1, YM = 7, XP = 6

these are arduino uno pins.

these correspond to the resistor matrix that MasterT was talking about.


this way these panels don't possess a touch controller IC, only the bare resistive touch panel.

Regarding the libraries, I'm using STM32 microcontroller and not Arduino, I'll have to search or create my owns.

Again, thank you very much for the help.

Best regards, Mauro.
 
P.S. hope the next display doesn't arrive broken.... 

[sairfan1]

If it was damaged while shipping you can open dispute and get new TFT (at least on aliexpress i never had any issue regarding disputes)

Mostly Chinese TFTs come with XPT2046 touch driver if it does not exist on PCB you can buy one and drive touch panel through this, you can find lots of sample code for this driver.

[senso]

Its a resistive touch, use 4 pins that have adc capabilities, and you can read it with a simple scanning routine, then, calibrate the touch values using at least 4 corners and the rest is interpolated.

[picandmix]

Hi,

Have only used the smaller 2.4 and 2.8" versions of those screens.

You will find working code in the AdaFruit and RinkyDink sites.


eg

// UTouch_QuickDraw
// Copyright (C)2015 Rinky-Dink Electronics, Henning Karlsen. All right reserved
// web: http://www.RinkyDinkElectronics.com/
//
// This program is a quick demo of how to use the library.
//
// This program requires the UTFT library.
//
// It is assumed that the display module is connected to an
// appropriate shield or that you know how to change the pin
// numbers in the setup.
//

#include <UTFT.h>
#include <UTouch.h>


https://learn.adafruit.com/category/graphic-tfts

#include "Adafruit_GFX.h"     
#include "Adafruit_ILI9341.h"
#include "UTouch.h"