Y axis inverted on 3.5 screen

[erasmo]

Hi Zynthianers!,

I am building a “mini-micro-Zynthian”. If my investigation is correct, probably is the tiniest one to the moment.

Now I am facing an issue on the screen 3.5. An issue that have found in many instances throughout many posts about similar problems. I have been testing too some of the solutions provided with no luck until now.

All the system is working fine except for one reason: the Y axis works in reverse when using a stylus. I have found several solutions on the web but I have not been able to make it work anyone.

I have attached a screenshot of the system together a photo of the screen, whose specifications are:

Screen size: 3.5 inches
LCD type: TFT
Module interface: SPI (supports SPI input up to 125MHz)
Resolution: 320*480 (pixels)
Touch screen controller: XPT2046
LCD controller: ICILI9486
Backlight: LED
Power consumption: 0.16A * 5V
Working temperature (℃): -20 ~ 60
PCB module size: 85.42 * 55.60 (mm)

This is the main drawback to finish the project. Any solution should be highly appreciated

[erasmo]

PROBLEM SOLVED!

After some tests and more tests I have found a solution which is working. I have rebooted several times to confirm that the touch coordinates perform adequately. Well, I must say that adequately is a way of talking because the behavior is not as precise as It should be but I asume that is normal on this kind of screen.

How to fix an Y axis inverted on the described 3.5 screen?

Here is my dummies guide:

Open terminal on Zynthian GUI (graphic user interface) menu SYSTEM/ Terminal

-write:

sudo raspi-config

-this will open a graphic menu

-displace with cursor keys to option 3 Performance Options

-select option P2 Overlay File System Enable/disable read-only file system

this, will ask you:

Would you like the overlay file system to be enabled?

Select Yes and Enter

Quit

Now, on the HARDWARE/Display Config add Invx after a comma at the end of the line (in spite that we are going to correct Y axis)

The string should be as follows:

dtoverlay=piscreen,speed=16000000,rotate=270,invx

Is working for me!

[Aethermind]

Good to know @erasmo, this is a useful tutorial, for future applications of the same micro- screen!

Best regards

[riban]

Why do you need to enable read-only file system and does this stop other zynthian features working?

[erasmo]

Many thanks @Aethermind !

[erasmo]

Hi @riban !

No idea Riban. I got this working, after trial and error and touching and retouching. I must say that everything works now, though is pending a practical deep test…