screen changes from white to a strange mosaic when starting and then comes my start screen

[rzapp]

Hi

How can I avoid, that the screen shows a strange mosaic during boot up or the last screen after e reprogramming of the chip?

Thanks for your answer

[Martin KJELDSEN]

Hi,

Please specify TouchGFX version, how you created the project, and show me an example of this "strange mosaic" 🙂 I have a feeling it's just garbage memory - Something we've tried to compensate for in 4.12.3 (you're probably using 4.10.0) because sometimes it would be possible to start up faster than TouchGFX could render the first screen.

[rzapp]

Hi Martin

First of all I'm working with 4.10.0 and I'm trying to update to 4.12.3. I create the project starting from cubeMX (5.4.0), touchGFX 4.10.0 and SW4STM32

I have also the feeling that I see garbage memory.

So this could be solved by updating to 4.12.3? Do you know how I can write something in the memory (permanent?) before TouchGFX starts render the first screen?

Thank you

rosario

[Martin KJELDSEN]

Just write something after you've set up your memory and it is addressable, before TouchgFX starts. But it won't be permanent unless your canvas dimensions are smaller than the displays. Otherwise TouchGFX will just overwrite it.

It probably won't be fixed by upgrading - Which board is this? Probably something with double framebuffer. For fun, try configuring only a single - thenit should work. If it isn't fixed by upgrading i'll show you how to get around this problem by only activating the LTDC layer when there's something to display.

e.g. imagine that you're activating LTDC layer 0 which is pointing to some address (set by TouchGFX in the concrete HAL for this MCU). But TouchGFX only renders in the framebuffer that is NOT being displayed when double fb is configured. If nothing is ever drawn again (E.g. an application with a box) then you're simply displaying garbage memory.

/Martin

[Ozone]

The LCD driver's GRAM will contain random values after power-up, until you properly initialize the chip. Or keep the last contents until you change it (re-program).

If you want to avoid it, you can try to dim the backlight, with a "default-off" state (0%) at startup, making the random "mosaic" invisible.

I used to view this temporary random image at startup as trivial side issue with my graphic projects.