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TMS570LC4357: Concurrent access to the peripherals connected to the same PCRx

Bartlomiej Gos
Prodigy 230 points
Part Number: TMS570LC4357


Hello,

I'd like to know what would happen when there are two masters accessing the same PCRx connected peripherals at the same time.

For example, let's say that the CPU is continuously polling the LIN/1SCI1 peripheral and sends/receives data over that interface and the DMA controller is continuously reading and writing from the MibSPI5 memories to handle the data transfer there.

Both peripherals are connected to pcr3:

What impact can be expected on the concurrent access to the same PCR bus? Is parallel access possible? If not, how is the concurrent access arbitrated?

Kind Regards,

Bartek

  • 0
    TI__Mastermind 49120 points

    Hi Bartek,

    As you suspected, parallel access is not possible when multiple bus masters (CPU, DMA, ...) are accessing the same slave target. The PCRx is only able to support a single access at a time, so the arbitration between the multiple accesses is done within the "Peripheral Interconnect Subsystem" in the above figure.

    This is a round-robin arbitration so that none of the bus masters blocks the other bus masters from getting their accesses completed.

    Regards, Sunil

  • 0 in reply to Sunil Oak
    Prodigy 230 points

    Thanks for the answer Sunil,

    Now I took a look into the Interconnect chapter in the TRM, but could not find any details about the arbitration.

    What's the time slice for the round robin arbitration? For how long one master can block the other from accessing the PCRx bus?

    Regards,

    Bartek

  • 0 in reply to Bartlomiej Gos
    TI__Mastermind 49120 points

    Bartek,

    The arbitration is done using a round-robin method, and switches between bus masters within 6 HCLK cycles.

    Regards, Sunil