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AM335x EDMA in burst mode

Sergio Kamakura
Expert 2495 points

Hi

I am using AM335x GPMC in burst mode ( NAND mode, 16 burst length ), but, I don't know if EDMA must be programmed specifically to acess GPMC in burst mode. EDMA is not correctly working with INCRemental mode when GPMC is in burst mode.

If I use EDMA to transfer in INCRemental mode ( GPMC in NOR mode = not burst ), I can transfer 675Kbytes successfully in 32mS.

How to correctly program the EDMA for GPMC burst mode?

Sergi

  • 0
    TI__Guru**** 393215 points
    Hi,

    What software are you using? What is connected to the GPMC?
  • 0 in reply to Biser Gatchev-XID
    Expert 2495 points
    Hi Biser

    I am using linux.

    There is a video buffer FIFO connected to GPMC with 16 bits wide data bus. This configuration don't use address bus, only CS1, RD and GPMC_CLK signals.

    This configuration is operating normally if I do an incremental EDMA transfer in NOR mode ( asyncronous mode without AAD multiplexation ). I can transfer through EDMA, 675Kbytes ( full frame of 720x480x2 pixels ) in 32 mS. Our goal is to achieve less transfer time.

    When I shift to NAND mode (synchronous mode with AAD multiplexation ), looking for RD, CS1 signals in oscilloscope, I can see that burst it is not happening.

    I did try all possible combinations in GPMC configuration, but, unsuccessfully.

    We are wondering if EDMA must be programmed accordingly with burst mode in GPMC.

    Sergio
  • 0 in reply to Sergio Kamakura
    TI__Guru**** 393215 points

    Sergio Kamakura said:
    When I shift to NAND mode (synchronous mode with AAD multiplexation ), looking for RD, CS1 signals in oscilloscope, I can see that burst it is not happening.

    NAND mode is completely different. It uses commands and addresses sent to the peripheral over the data bus. You should try synchronous NOR mode.

  • 0 in reply to Biser Gatchev-XID
    Expert 2495 points
    Hi Biser

    Wow, that's nice.

    I wondered that burst mode should be in NAND mode only.

    I will try synchronous NOR mode and will report the results.

    Thanks a lot.

    Sergio
  • 0 in reply to Sergio Kamakura
    Mastermind 9655 points


    Hi Sergio,
    Did you try synchronous NOR mode?
    Could you share the result?
    I would like to know wheter NOR flash burst read with DMA is possible, or not.
    There are lots information for this topic as you know, it makes me confused.

    Best regards,
    Kanae

  • 0 in reply to Kanae
    Expert 2495 points
    Hi Kanae

    I finalized the project using asynchronous mode, accessing GPMC with EDMA asynchronously. The burst mode didn't work with GPMC. Perhaps it is lack of knowledge from my part, but, due shortage of time, I finished the project with asynchronous mode and the video digitalizer worked very well.

    Thanks.

    Sergio
  • 0 in reply to Sergio Kamakura
    Mastermind 9655 points

    Hi Sergio,

    I appreciate sharing your experiance.

    If you do not mind, could you tell me why you have chosen  using asynchronous mode?

    Best regards,
    Kanae