STM32U5A9J-DK move framebuffer to external ram with strange frames

MMess.1 · ‎2023-08-16

Hi

I'm playing around with the STM32U5A9J-DK and have setup a projected generated by the TouchGFX Designer for this Board. The application works well.

If i adapt the linker file to move the framebuffer to external ram all animations and fast changing images are disturbed. When just showing static screens, they are displayed correctly. Using the framebuffer form the internal ram it works as expected.

I only changed the FramebufferSection in the linker script to go into the PSRAM instead of the RAM.

  FramebufferSection (NOLOAD) :
  {
    *(TouchGFX_Framebuffer TouchGFX_Framebuffer.*)
    *(.gnu.linkonce.r.*)
    . = ALIGN(0x4);
  } >PSRAM // instead of RAM

Static screen with no user interaction:

Screen when the scrolling container is moved:

Attached, you will find a video to see it while scrolling and when static image is viewed.

I expected the external Ram on the DevKit is intended to use for the frame buffer isn't it? So why is it not working here? Do i need to change more the just the linker script? Is the embedded PSRAM to slow for my use case?

Best regards

Martin