New TFT: image "inversion"


I am trying to manage a TFT with a RGB interface in my S7 synergy project. The result by now is that the image displayed is affected by an inversion: it is like if it's viewed from behind the screen: please see the capture below as an example:

Is there something wrong in my configuration? Or have I to correct it with the code?

My display driver configuration is as follows:

How can I correct the problem?

Thank you in advance,


  • Hi Laser,

    please could you show how did you connect the screen with S7? Have you used Starter or Development Kit? The configuration of pins ("Pins" tab) might also be useful.



  • In reply to adboc:


    I am using a PE-HMI1 demoboard. The display that I am trying to connect has the same 40-pin connector pinout of the display provided with the PE-HMI1 itself.

    Here is the configuration of pins:


  • In reply to adboc:

    Hello Laser,

    Please verify that your hardware is configured correctly. If there are any "mode" pins, make sure that they configure your display to scan left to right and then top to bottom. Rendering functions provided with GUIX on Synergy cannot produce mirrored image so the problem is most likely down to hardware configuration.


  • In reply to Laser:

    Thank you, I will check immediatly. As I told before, if I connect the display provided with the PE-HMI1, the image is correct. Is it possible?

    So, as far as I see, is this a "graphic effect" that is not possible to configure in the configuration.xml file?


  • In reply to Laser:

    Hello Laser,

    Unless your display is identical to the one on the PE-HMI1 kit, the configuration is likely to be different. Please verify on the schematic which pins are used for scan direction and set them to the correct value (either through software or at the hardware level). Alternatively, you can set "Input - Graphics screenX input line descending" to "Used" and you'll effectively have your display upside down.


  • In reply to Karol:


    I tryied to set the "Input - Graphics screenX input line descending" to "Used": after powering on the board, I saw for a moment the image on the screen as expected, after that the screen became black. Perhaps are there any other parameters to re-set along with the "Input - Graphics screenX input line descending"?

  • In reply to Laser:


    If you post up the datasheet for that LCD I can help you figure this out.


    Edit: I want to mention that I have seen some LCDs that when they failed/broke, the picture when backwards. So it is possible if the flex tail got punctured or ripped, the picture could be backwards even if all of your pull-up/pull-down connections are correct. So make sure to try another LCD once you double check all of the input mode pins. 

  • In reply to Bill:

    Hello Bill,

    thanks for your interest; now my problem is the following: the image is displayed right (I set the "Input - Graphics screenX input line descending" to "used", but when I touch the screen, the image becomes blank or "blurred"; when I release the touch, the image sometimes returns to the correct view, sometimes not:

    Right view:

    Bad view when I touch the touchscreen:

    This is the configuration for the GUIX Port on sf_el_gx block:

    And this one for the Display Driver on r_glcd:

    My display is a DLC0700O2ZG-T-1 with a FT5426 as touch driver.

    It seems the view slides out of the active window when the touch is pressed. How can the touch modify the RGB data?

    Anyone can help? Let me know if you need some other information about the hardware.


  • In reply to Laser:


    How could I change (invert) che horizontal/vertical scan direction by hardware in order to flip the view on the display?

    Have I to invert the VSYNC and HSYNC pins on the microcontroller?

    Thank you!

  • In reply to Laser:

    Changing the scan direction is a function of the LCD display being used, some LCD displays support this feature, some don't. There is nothing you can configure in the Synergy GLCDC or SSP. You would need to look at the LCD Display data sheet (or the controller used on the LCD display) to understand if the LCD supports changing the scan direction, and how to modify the scan direction.

  • In reply to Jeremy:

    From looking at the datasheet for the DLC0700O2ZG-T-1 LCD display, it seems to have a fixed scan direction (there are no HW pins on the display interface to configure scan direction, and no communication interface to configure the LCD Controller. The only communications interface is the I2C interface for the FT5426 touch controller).