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AM2434: Timer and connection to DMA

Leo Clouet
Prodigy 55 points
Part Number: AM2434
Other Parts Discussed in Thread: SYSCONFIG

Hi,

I am working on the AM2434 and I would like to configure a timer to generate a 110MHz interrupt. This interrupt, would trigger a DMA transfer that would eventually be connected to a DAC via the GPMC.

With the MAIN_PLL2_HSDIV6_CLKOUT clock, that runs at 225MHz, I could do that. In the sysconfig interface, the time allows only a tick period in microseconds. That means that I cannot go faster than 1MHz. Can the timer go faster (around 8 nanoseconds)? Is this a hardware limitation or an interface limitation?

On another subject, I have not found any way to connect the timer interrupt to a DMA trigger? Is there something I miss?

Thank you,

Leo

  • 0
    TI__Mastermind 24593 points

    Hello Leo,

    Thank you for your patience here.

    Let me reach out to SysConfig module expert, as well as the DMA owner to determine device connectivity and 110MHz GPMC->DMA interrupt trigger use-case feasibility.

    Best Regards,

    Zackary Fleenor

  • +1
    TI__Mastermind 24593 points

    Hello Leo,

    1) There is a sneaky note found in the DMTIMER chapter that states the following functional hw limitation:

    Functional frequency range: freq(timer clock) < freq(interface clock)/4.

    For AM243x devices, the interface clock = SYS_CLK=500MHz / 4 = 125 MHz (TRM IP Integration diagram below)

    therefore:

    freq(interface clock)/4 = 125 MHz /4 = 31 MHz

    31 MHz (or 32.258 ns) is the Maximum Functional Frequency for any DMTIMER instance.

    I will submit a request for SDK to enable enhanced period selection functionality for Timers to support both microseconds and nanoseconds depending on application requirements and SoC clock configuration/connectivity.

    2) You can also see from the IP Integration diagram that the device only supports interrupts to GICSS (A53SS/COMPUTE_CLUSTER0) and R5FSS[0:1]_CORE[0:1] VIM/INTR, therefore no direct HW DMA trigger is available. A software based solution would need to be found which might result in consuming additional CPU bandwidth.

    https://ti.com/lit/spruim2 

    AM243x TRM - Peripherals - Timer Modules - Timers - Timers Integration (pg. 8795-8809)

    Best Regards,

    Zackary Fleenor