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HansPLJ
Associate III
February 5, 2024
Solved

DMA request generation on STM32H7

  • February 5, 2024
  • 3 replies
  • 1977 views

Hi!

I am looking into the possibility on using LPTIM1 to trigger a DMA transfer with no CPU interrupt. This timer is chosen because it can be clocked directly by the HSE clock input. In the datasheet of STM32H7B3 (DS13139 - Rev 8) table 4, it states that LPTIM1 cannot be used for DMA request generation. In table 103 in the reference manual (RM0455 Rev 11) lptim1_out is listed as as a resource. 

Does this mean that it is not possible to use an output from LPTIM1 directly as an DMA request generator, but it is possible when using the DMA mux?

Any clarification would be appreciated! 

 

 

Best answer by FBL

Hello @HansPLJ 

It is not possible to use directly DMA request generation. However, you can use it through DMAMUX. Your interpretation is correct.  By using a DMAMUX, you can dynamically switch the DMA channels source based on your system's requirements at any given time. This allows for more efficient use of the available DMA channels and greater flexibility in your system design.

3 replies

LCE
LCE
Principal II
February 5, 2024

I don't know that H7 / LPTIM. Check the LPTIM CR / IE registers, is there any "DMA enable" bit?

F
FBLAnswer
Technical Moderator
February 5, 2024

Hello @HansPLJ 

It is not possible to use directly DMA request generation. However, you can use it through DMAMUX. Your interpretation is correct.  By using a DMAMUX, you can dynamically switch the DMA channels source based on your system's requirements at any given time. This allows for more efficient use of the available DMA channels and greater flexibility in your system design.

To give better visibility on the answered topics, please click on Accept as Solution on the reply which solved your issue or answered your question.Best regards,FBL
    H
    HansPLJAuthor
    Associate III
    February 5, 2024

    Thank you for the clarification! 

      mƎALLEm
      mƎALLEm
      Technical Moderator
      February 5, 2024

      Refer also to the AN5224 "STM32 DMAMUX: the DMA request router"

      To give better visibility on the answered topics, please click "Best answer" on the reply which solved your issue or answered your question.
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