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SK-AM64: clock sync

Vincenzo Pizzolante
Mastermind 25436 points

Part Number: SK-AM64

hi,

we are currently evaluating AM64xx on the SK-AM64: is there an easy way to use the 25MHz system clock via a CLKOUT pin for external peripherals
to be brought out and used without changing various PLL clocks / multiplexers and dividers via registers?

Basically to have 3x GPIO as CLOKOUT sync'd ( I'm looking for a solution to feed up to 3x external Ethernet PHYs with 25MHz ).

KR
Vincenzo
  • 0
    TI__Guru 63035 points

    OBSCLK0 is the only AM64x clock signal that is not generated from one of the internal PLLs. However, this clock output is only multiplexed to one pin. Software would need to configure the pin multiplexer to select this function and there is no way to prevent the attached device from seeing a short clock since the mux mode change is not synchronized to the clock output. This clock output is only provided as an observation clock.

    Your customer should consider the approach implemented on the AM64x EVM, where an external LVCMOS clock source is used as the system reference clock and distributed to multiple devices. Note: This approach requires a single input to multiple output buffer so each device receives its clock from a dedicated clock output with point to point connectivity. Any attempt to clock multiple devices from a common clock output is likely to be problematic.

    Regards,
    Paul