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BRado
BRado
Associate II
February 10, 2020
Question

Application Fails when Framebuffer stored into an external RAM

  • February 10, 2020
  • 2 replies
  • 1197 views

The STM32CUbIde dont support TouchGFX yet to build a project based on STM32L4R9AII6, so I build my own project . I faced a very serious problem when I try to put a FramBuffer into an external RAM configured as memorymap (OCTOSPI) .

 When I do this a vertical lines are displayed (see attached image) and the image quality is degraded

Please can you give me a possible solutions.

Thank you.

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2 replies

berendi
berendi
Principal
February 10, 2020

Check the external RAM interface (QSPI) configuration, the memory bandwith should be sufficiently higher that the display pixel clock.

Exactly how much hgher depends on the framebuffer format.

BRado
BRadoAuthor
Associate II
February 10, 2020

Can you give me please more informations about modifing ​the memory bandwith ? ( parametres to change  )

berendi
berendi
Principal
February 10, 2020

There is no MCU named STM32L4R9I, I assume you are using STM32L4R9AII6.

Review the following chapters in the reference manual

6.2 Clocks, PLLCFGR and CCIPR2 registers, figure out the octospi kernel clock frequency, and whether you need any higher. Check that the PLL clock source actually runs.

19.4 OCTOSPI functional description, and register descriptions.

and the datasheet of the external memory to find out the supported timings and transfer modes.

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