tony1812
Posts: 330
Joined: Sat Jul 15, 2017 12:40 pm
Location: Boston MA.

How to calibrate 3.5" LCD?

Mon Feb 19, 2018 7:40 pm

On and off, for the past few days, I unsuccessfully try to get the 3.5 LCD display working on my pi3 with the latest stretch. The LCD is this:
Keyestudio TFT LCD Display 3.5 Inch 480x320 16-bit TFT Touch Screen LCD Shield for Raspberry Pi Model B B+ A+ A Module
a wareshare35a lcd

I followed this instruction to install the driver:
https://www.elecrow.com/wiki/index.php? ... spberry_Pi

After reboot, the LCD works. But the touches are all off, when I use the mouse to click on an icon, the correct icon opens the correct app, no a problem. However, this doesn't hold true for finger tap nor for stylus. when I tap on an icon with my finger or use the stylus. the mouse curser does not response to the right location on the LCD, for example, when I click on and icon on the lower left side of the LCD, the mouse curser stay on the upper right side time pi icon. It opens a calendar instead. I tried to calibrate it with the xinput-calibrator, pasted the data to the /etc/X11/xorg.conf.d/99-calibration.conf, reboot. Nothing changes. Have I missed some steps? Thanks.
Last edited by tony1812 on Tue Feb 20, 2018 12:58 pm, edited 1 time in total.

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topguy
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Joined: Tue Oct 09, 2012 11:46 am
Location: Trondheim, Norway

Re: How to calibrate 3.5" LCD?

Tue Feb 20, 2018 11:42 am

Post the content of your 99-calibration.conf here maybe. ( using [ code ] [/ code] ) tags )

tony1812
Posts: 330
Joined: Sat Jul 15, 2017 12:40 pm
Location: Boston MA.

Re: How to calibrate 3.5" LCD?

Tue Feb 20, 2018 12:50 pm

Thanks for the reply.
Than content of the 99-calibration.conf is :

Code: Select all

ection "InputClass"
	Identifier	"calibration"
	MatchProduct	"ADS7846 Touchscreen"
	Option	"Calibration"	"29 1231 1173 212"
	Option	"SwapAxes"	"1"
EndSection
Is there something wrong with it? One thing I don't quite understand is this Option "Calibration" "29 1231 1173 212", I read that they represent minX, max X minY and maxY, but the LCD is only 480x320, why are there numbers like 1231 and 1173 came from? Shouldn't they be in the range of the LCD?
And also Option "SwapAxes" "1", I suppose it is fo the LCD orientation, so is 1, 2, 3, and 4. represent the 4 orientations, or is it 0. 90, 130. 270.? Thanks again.

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topguy
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Location: Trondheim, Norway

Re: How to calibrate 3.5" LCD?

Tue Feb 20, 2018 2:01 pm

You are missing the starting "S" of Section.

tony1812
Posts: 330
Joined: Sat Jul 15, 2017 12:40 pm
Location: Boston MA.

Re: How to calibrate 3.5" LCD?

Tue Feb 20, 2018 2:29 pm

That was a copy and paste to this forum mistake, In the file itself it has the "S". Anything else is wrong?

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topguy
Posts: 4428
Joined: Tue Oct 09, 2012 11:46 am
Location: Trondheim, Norway

Re: How to calibrate 3.5" LCD?

Tue Feb 20, 2018 2:34 pm

You could also check "/var/log/Xorg.log" to see if you can find evidence that this file is loaded.

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