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AM625: Accessing the GPMC from PRU

Stuart Baker
Genius 10620 points
Part Number: AM625

I have a customer asking if it is possible to access the GPMC peripheral for read/write from the PRU-ICSS subsystem. In the AM62x TRM, there is a "Table 3-6 Connectivity Table among Initiators and Targets" where I would expect to find the answer. Though the PRU-ICSSS (ICSSM0) initiator is in the table, there does not appear to be a GPMC target in the table.

Is the GPMC accessible from the PRU? Is the GPMC target missing in the table an oversight?

Thanks,

Stuart

  • 0
    TI__Guru**** 188979 points

    Hello Stuart, 

    Thank you for the note.

    I am checking internally and will update you.

    Regards,

    Sreenivasa

  • 0
    TI__Guru** 100740 points

    Hello Stuart,

    Can you describe the usecase in more detail?

    In general, PRU should be able to read pretty much any address in memory space, and write to any address that does not require elevated permissions (e.g., PRU can read pinmux register settings, but PRU cannot write new pinmux settings to the registers).

    However, depending on exactly what the customer is trying to do, it may or may not make sense to try to use the PRU with the peripheral.

    When I look at the "Interrupt Connections Summary" table in the AM62x TRM, GPMC lists ICSSM as a "no". So the simple answer is, "if the usecase requires the GPMC to be able to interrupt the PRU, then the usecase is not supported".

    There may be some way to route a single interrupt from the GPMC to the PRU through the Interrupt Aggregator, but I have not looked into the Interrupt Aggregator much at this point in time.

    Regards,

    Nick

  • 0 in reply to Nick Saulnier
    TI__Guru**** 188979 points

    Hello Stuart,

    Thank you for the patience. Please refer inputs from the expert.

    Looks like the below table has an error. “Y” – maybe should read “GPMC0”

    Table 3-6. Connectivity Table among Initiators and Targets

    The ICSSM has physical path to GPMC and ELM end points

    Regards,

    Sreenivasa