Touch Screen Accuracy. [solved]


I have an issue that I am trying to sort out. I am using an Arduino Mega and a 3.5’’ TFT Screen.

As I move away from the ribbon side of the screen the touch location does not match where the screen detects the touch. It progressively gets worse the further from the ribbon side of the screen you get. ( see images). I am unsure how to correct the issue. Any help would be appreciated.

Go on. Post a link to the actual screen that you bought e.g. Ebay sale page.
Or post a photo of the pcb side.

Then we can identify your hardware.

Which library(s) are you using?
Then we can point you to the library example(s) that show you how to calibrate and use the Touch Screen.

Hint. Post links to hardware. Libraries by name. (or links if not supported by Library Manager)
This takes 5 minutes of your life.
But you probably get an accurate answer in the first reply.
Following the Forum "posting advice" ensures happy readers.



Thank you for your quick response, sorry for the incomplete information.

The Screen is made by Kuman

The Libraries I am using in the sketch are (they were included on disk that came with the screen) :

#include <Adafruit_GFX.h>
#include <MCUFRIEND_kbv.h>
MCUFRIEND_kbv tft;
#include <TouchScreen.h>

I did run the screen calibration from the example that was included with the screen, I attached an image of the results.

I entered the values provided into the sketch:

uint16_t TS_LEFT = 915;
uint16_t TS_RT  = 113;
uint16_t TS_TOP = 937;
uint16_t TS_BOT = 64;

Again, thanks for the help.

I would leave the IDE. Delete any library folder that came with your CD.
Start the IDE. Install Adafruit_GFX and MCUFRIEND_kbv via the IDE Library Manager.

Run the examples.
The Calibration sketch reports to the Serial Terminal.

Ask if you have any problems.

Oh, it would be "interesting" to know what library versions came with your Kuman disk.
If you are in a good mood, please run the Library Manager to see what the version numbers are. (before deleting them)



I checked the versions per your request. ADAFRUIT_GFX version = 1.0.2 ( looks VERY old) the MCUFRIEND_kbv, does not show as being installed by looking in the library manager, but the fact that i can load the sketch would suggest otherwise. Now i know in the future, not to rely on the disks and reference library manager. I have deleted both and will re run the calibration. Thank you again for the help.


I verified the settings in the new libraries per your suggestion. The numbers actually matched very closely to what I already had. I entered the new numbers in but with no change. I tried a secondary screen, at first it still seemed off a little, but was much better so I ran the calibration again on that screen and it worked. The screen was defective, thank you for your support and help, sorry for the delay in responding back with the results.