2.4 inch tft LCD ili9340 touch problem

Other Hardware Displays
1

hi !

my 2.4" lcd shield from mcufriend have problem with touch calibration:
the "TouchScreen_Calibr_native" code reports the Broken Touch !
the serial monitor report of "Touch_shield_new" is:

Most Touch Screens use pins 6, 7, A1, A2
But they can be in ANY order
e.g. right to left or bottom to top
or wrong direction
Edit name and calibration statements

Please Calibrate.
ID=0x9340
Screen is 240x320
Calibration is:
LEFT = 907 RT = 136
TOP = 942 BOT = 139
Wiring is always PORTRAIT
YP=15 XM=16
YM=7 XP=6

===============================

when testing with "Adafruit_TouchScreen-master" library there is a response from bottom of touch and the Pressure value changes. but the top of the touch need more pressure to change the pressure value.
the serial monitor report of "touchscreendemoshield.ino" is:
when not touched ---> pressure=100~117
when touched ---> pressure=420~560

===============================

how can i fix this? its possible pin of the touch is different: XP,XM,YP,YM

why YP,XM not A1,A2 in serial report?

thank you !!!

2

If the Calibration sketch says "Broken TouchScreen" it means that either there is no Touch Panel or the glass is cracked.

If you don't believe the sketch, read the resistance with a DMM.

There is an updated Calibration sketch with a link in this message

There is no point in calibrating a missing or broken TouchScreen.
If you have a good panel but bad calibration, please copy-paste from the Serial Terminal to your message

David.

3

thank you !

im testing with multimeter when shiled not connected to uno the resistance between XP,XM is infinite !!!
is it my test true? or must be turn on the shield and make test?

and this is the serial message from updated sketch:

TouchScreen.h GFX Calibration
Making all control and bus pins INPUT_PULLUP
Typical 30k Analog pullup with corresponding pin
would read low when digital is written LOW
e.g. reads ~25 for 300R X direction
e.g. reads ~30 for 500R Y direction

MISSING TOUCHSCREEN
ID = 0x9340

4

Look at the front of your shield.
A Touch Panel has a gold stripe around the outside with four gold strips at the bottom right of the screen.
A 4 way ribbon joins the gold strips.

Compare your shield with photos of genuine Touch Shields.
Or post a photo.

David,

5

okay !

i check the lines aroud the lcd at the middle-top of the screen has a space(like 45 degree cut) and also there is a space at the bottom of lcd. is this cutting or space okay?

4 pin connector seems to be okay and firmly connected to pcd !

now im sending some photo !!!

tnks !

IMG_20191014_132209.jpg
IMG_20191014_132209.jpg2336×4160 859 KB

6

Your photo shows the top of the screen. Any Touch Panel electrodes will be at the bottom of the screen.

Yes, it "looks" like the top of a Touch Panel. It also looks as if the electrode has a diagonal cut near the pushbutton K1.

Please post a photo of the whole screen.

David.

7

and i this is the bottom image:

IMG_20191014_132236.jpg
IMG_20191014_132236.jpg2336×4160 761 KB

8

and total screen image:

forum cant allow me to send post repeatedly! (im new member) :frowning:

IMG_20191014_132303.jpg
IMG_20191014_132303.jpg2336×4160 988 KB

9

You definitely have a Touch Panel. Ribbon at bottom left. Icons are a pretty big clue !!!

I have always assumed that the printed gold electrodes will be on the underside of the glass.
Is your diagonal cut on the surface of the glass?
You have a second diagonal cut near the "Home" icon. The Touch Panel was deliberately damaged.

If your Shield was advertised as a "Touch" display, ask the shop for your money back.
The Touch does not work.

David.

10

yes shield have a touch in the shopping website !

these not cut like something with knif, just two spaces !!! yes on the surface

the glass havnt any cut or crack- i look it with flashlight, edge of glass is normal and not seem to be broken !

testing LCD-D7 and LCD-WR pins dont show any resistance(ohm)!!!
and also for D6 and RS pins
but when i press the screen multimeter shows ~3Mega ohm

i think buy another because the seller wont give back modules !

11

if i want to buy the new touch lcd, that one should havnt any spaces around the lcd ? is it true?

---> thank you for helping <---

12

A regular 2.4 inch Mufriend shield will look like your photos but without the diagonal cuts.

Any Ebay vendor will refund 100% immediately. You have received damaged item. They will not ask you to return the item.

Any local shop will replace the item with good shield.

In theory AliExpress require you to return the item.
In practice I doubt if they will make a fuss.

Both Ebay and AliExpress can resolve "disputes".
Both Ebay and AliExpress accept and publish buyer feedback.

No vendor wants to see this sort of complaint.
You have photographic proof that the items were supplied as damaged goods.
This is very different to an item that was "damaged in the mail" or damaged by the user.

It is very important that buyers report problems to Ebay, AliExpress, web shop.

If you have trouble with Ebay, Ali, local shop, ... report the shop on this Forum e.g. link to the Ebay sale or shop website.

David.

13

thanks !

im in iran and they say the customers only have 24~48 hours for testing any modules and after that the seller
cant give back or payback money !

but im calling shopping site admin for this

14

I am sure that Iranian shops will give you 100% service.

If they sold it as a Touch Screen, they should either replace or refund.

David.

15

i forget to say, at first time i program this sketch to uno and test lcd !!!
is it possible this program change the lcd registers in chip ili9340 ?

i upload my first test code:

==============

in this picture there is space aroud the lcd:

550×663 51.6 KB

ILI9340[main lib].zip (3.22 KB)

9340uno[RGB test code].zip (1.79 KB)

16

finally problem finds !!!

the 4-wire touch connector is not connected good to PCB !
when i pess and hold the connector the touch program running ...
but says "unusual calibration range"

=====touch calibr report=====

TouchScreen.h GFX Calibration
Making all control and bus pins INPUT_PULLUP
Typical 30k Analog pullup with corresponding pin
would read low when digital is written LOW
e.g. reads ~25 for 300R X direction
e.g. reads ~30 for 500R Y direction

Testing : (A1, D7) = 31
Testing : (A2, D6) = 23
Diagnosing as:-
YP,YM: (A1, D7) = 31
XM,XP: (A2, D6) = 23
ID = 0x9340

cx=313 cy=793 cz=1017 LEFT, TOP, Pressure
cx=885 cy=541 cz=595 LEFT, MIDH, Pressure
cx=891 cy=883 cz=519 LEFT, BOT, Pressure
cx=568 cy=201 cz=628 MIDW, TOP, Pressure
cx=556 cy=871 cz=428 MIDW, BOT, Pressure
cx=226 cy=199 cz=607 RT, TOP, Pressure
cx=223 cy=541 cz=480 RT, MIDH, Pressure
cx=222 cy=875 cz=319 RT, BOT, Pressure
MCUFRIEND_kbv ID=0x9340 240 x 320

const int XP=6,XM=A2,YP=A1,YM=7; //240x320 ID=0x9340
const int TS_LEFT=748,TS_RT=528,TS_TOP=362,TS_BOT=562;
PORTRAIT CALIBRATION 240 x 320
x = map(p.x, LEFT=748, RT=528, 0, 240)
y = map(p.y, TOP=362, BOT=562, 0, 320)
Touch Pin Wiring XP=6 XM=A2 YP=A1 YM=7
LANDSCAPE CALIBRATION 320 x 240
x = map(p.y, LEFT=362, RT=562, 0, 320)
y = map(p.x, TOP=528, BOT=748, 0, 240)

*** UNUSUAL CALIBRATION RANGES -200 -220

================

is it possible to resolder this 4-wire pins? it likes plastic cable !

17

I had a close look at a regular 2.4 inch shield.
Sure enough, it has diagonal cuts in the printed gold electrodes.
I have never noticed this before !!!

So your shield might be rescued.
If you are confident with soldering SMT components, you can attempt to re-solder the 4-way ribbon at the pcb end. I don't think that it is possible to rescue the printed electrode connections where the ribbon joins.

Your calibration is rubbish. Run the calibration sketch again (when you have rescued the Touch ribbon)

David.

18

yes, i have a doubt about these cuts on LCD but today buying new one !
and i see all of the 2.4" lcds have two diagonal space(cut) on it
when im testing the new shield its okay !

for repairing touch i think need to make new forum post (after doing that, and if its rescued !)

thanks David for developing library and program and for supporting.

19

I would just use the bad shield with non-Touch programs. It should show graphics, text, ... ok.

Use your new Shield with Touch projects.

David.