Only getting background color on the screen. No other graphic images appear.

[TSton]

I'm trying to get a new display board working. It has an STM32F469, and external SDRAM. Using STM32CubeIDE and TouchGFX to generate code. So far, all I get on the screen is a filled background color, as set it in LTDC settings. No other graphics . Does this mean that at least the external SDRAM and frame buffer are working correctly? I'm trying to narrow down where to look for the problem since every part of this task is new.  

[Martin KJELDSEN]

Hi @TSton​,

What were you expecting? I guess this means that the SDRAM/fb are working. Do you have an application running that draws something on screen? Did you try to debug if you can step through the code in your TouchGFX screens?

/Martin

[TSton]

Hi Martin,

I've made some progress on this. Here is what TouchGFX simulator shows, followed by what my display is now showing. I've experimented with various clock speeds and other settings to get it to this point. I'm getting FIFO under-run errors if I run the LCD clock faster than about 8MHz. I never get a clean image on the screen though. It seems like the image I want is painted, and then a bunch of noise sweeps over it at regular intervals.

Terry

[Martin KJELDSEN]

What is the black part of your application? Is that an actual box or an image? If you have nothing as background in your application you'd be staring into uninitialized framebuffer memory.

[TSton]

I haven't specified a background box in TouchGFX. In STM32CubeIDE, I've set the background colour to white in the LTDC settings by setting the red, blue and green colours to 255.