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Graduate II
January 13, 2025
Question

No Contiguous RAM size big enough for full FrameBuffer

  • January 13, 2025
  • 3 replies
  • 810 views

I am using the STM32H743VITX MCU and TouchGFX with the display (800x480px) in a single buffer format with RGB565. The framebuffer size is calculated to be 750KB; however, the MCU does not have a contiguous 750KB region in RAM.

 

I am exploring ways to utilize this resolution without adding external memory, such as SDRAM.

While I have looked into partial framebuffer rendering, this option does not appear to be available in CubeMX, and I am unsure why.

 

Does anyone know any other workarounds for this issue or why PartialFrame is greyed out for me in CubeMX?

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    3 replies

    Graduate II
    January 14, 2025

    Perhaps you need to find a panel with it's own SGRAM within the controller. Like SSD1963 or RA8875. And a driver that facilitates that..

    https://www.raio.com.tw/en/RA8875.html

    https://support.touchgfx.com/docs/development/scenarios/lowering-memory-usage-with-partial-framebuffer

    "Partial frame buffers will only work on displays that have built-in memory. These are typically DSI displays or displays with a parallel bus connection (DBI type A/B, 8080/6800) or SPI-bus connection."

    Graduate
    January 14, 2025

    If you are not going to use DMA for framebuffer access, try a FreeRTOS with heap 5 option.

    Graduate II
    January 14, 2025

    My original plan is to use the DMA. From what I've seen I thought it ill advised to not use DMA, have I been misinformed? Have you seen a Display not use DMA and still work fast enough and without any artifacts?

    Graduate II
    January 14, 2025

    For simple projects 565 isnt strict. You can use L8 buffer. And partial is based on used bus for display. LTDC dont support it.