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MSale.1
MSale.1
Senior
June 10, 2020
Solved

How to limit the transfer speed from the internal ram to the display when using touchgfx but without reducing the AXI bus frequency? The controller is STM32H743

  • June 10, 2020
  • 7 replies
  • 1319 views

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Best answer by waclawek.jan

You mean, reducing the pixel clock? It's ltdc_ker_ck, and that is the R output of PLL3 see RCC chapter.

So you have to change the R output of PLL3.

JW

7 replies

waclawek.jan
waclawek.janBest answer
Super User
June 10, 2020

You mean, reducing the pixel clock? It's ltdc_ker_ck, and that is the R output of PLL3 see RCC chapter.

So you have to change the R output of PLL3.

JW

MSale.1
MSale.1Author
Senior
June 10, 2020

@Community member​ 

Thnx

MSale.1
MSale.1Author
Senior
June 10, 2020

No not the pixel clock. i mean the speed of the bus it self for example in stm32h743 its 240Mhz at max frequency. i need to reduce it without affect the AHB2 bus

Tesla DeLorean
Tesla DeLorean
Guru
June 10, 2020

Yes the pixel clock, and the clocks the LTDC is using to drive the pacing of data fetches from the memory, it is a synchronous machine, want it slower, gear things down. Play with FIFO and BURST type settings to control how much data pulls at each interaction.

Don't have the bandwidth, then you're going to have to come up with a different approach.

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MSale.1
MSale.1Author
Senior
June 10, 2020

@Community member​ 

Ok Thnx!

berendi
berendi
Principal
June 10, 2020

Why? What problem would that solve?

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