Touchscreen/no IRQ

Other Hardware Displays
1

Hi.
Can anyone advise:
ILI9341 TFT controller, so I am assuming a XPT2046 Touchscreen. I am only getting an IRQ when the clock is running, even though the CS isn't on, which seems to me to defeat the point of an Interrupt.

Please advise.

2

On a closely related issue :any idea what would cause this or fix this ?
Arduino UNO clone. Nothing anywhere near the module.

IMG_20260726_225133
IMG_20260726_2251331920×1440 504 KB

3

Show a schematic and we can get started.

I have no idea what that means.

4

At this point you're guessing, and we're expected to assume your guess is correct.

An annotated schematic would be far more helpful than the picture you posted. A schematic shows how everything is actually connected, including which Arduino board you're using, the wiring, power connections, and any external components. Without that information, people can only guess at the cause of the problem.

5

can you give a link to the specific TFT?
the majority of ILI9341 TFT controllers use 3.3V logic even when powered from 5volts
the UNO use 5V loigic and direct connection to the TFT could damage it
use level shifters or move to a microcontroller which uses 3.3V logic

6

Apologies for the delay. Priorities changed.
Thanks for the good intentions.
TFT from Amazon says https://www.amazon.ie/dp/B0CZDP41DT?ref=ppx_yo2ov_dt_b_fed_asin_title "Onboard level conversion scheme, compatible with 5V/3.3V IO levels, supports various microcontroller IO connections", but it doesn't seem to work like that. It works fine on a "Due". I have several level converter modules.

7

although the TFT technical details in the link states

3. Onboard level conversion scheme, compatible with 5V/3.3V IO levels, supports various microcontroller IO connections

lower down is also states

VCC supply voltage: 3.3 V ~ 5 V.
Voltage of logical IO ports: 3.3V (TTL)

i.e. the supply voltage can be 3.3v or 5V (selected by J1 link on bottom of PCB) but the IO logic level is always 3.3V

and the Arduino Due tech specs states

I/O Voltage	3.3V

the TFT looks similar to one I have which uses 3.3v IO Logic

8

The display works fine on 5V comms and control. The touch, apparently not.

9

a interface which uses 3.3V logic when connected to 5V logic may die immediately, work for 10 seconds, 10 minutes, a day, a year or for ever - you don't know.
unless a 3.3V logic interface is specified as 5v tolerant use potential dividers or level shifters.