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PRU external memory interface

Mohsen Khayami
Mastermind 22391 points

Champs

When we access the external memory (DDR2/3) from the PRU I assume you need to add some NOP’s until the data becomes available or those the PRU waits until the data is available?

 

Thanks

 

Regards

Mohsen

  • 0
    Expert 1530 points

    No, you need not.

    The L3 interconnect logic handles this for you.

  • 0 in reply to sviss
    TI__Genius 15200 points

    Hi Mohsen,

    PRU writes are a fire-and-forget command that executes in ~1 PRU cycle.  You may need to add NOPs if the PRU application needs to wait until the data is available in external memory. 

    However, as sviss indicated, PRU reads are a “blocking” command that executes in ~2 PRU cycles, plus additional latencies due to traversing through SoC interconnect layers and variable processing loads.  As such, you do not need to add NOPs when reading external memory.

    Regards,

    Melissa