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ULPI - Full Speed USB

Matan Medalion
Prodigy 155 points
Other Parts Discussed in Thread: TPS65920

Hi,

I'm using the TPS65920's USB transceiver with OMAP35.  I would like to use the OTG ULPI interface, but I need only Full Speed rating. ULPI BUS works at 60MHz at HS, which requires strict layout. I would like to know whether when working FS only, the ULPI BUS clock can be slowed down.

 Thanks,

Matan

  • 0
    Intellectual 370 points

    Hi Matan,

    Irrespective of HS/LS/FS mode , the UCLK will always be 60 MHz. This is a requirement of the ULPI standard.

    Regards
    Ankit


  • 0 in reply to Ankit Somani15962
    Intellectual 370 points
    If we program the USB in the FS/LS-serial mode we will be able to cut off the ULPI CLOCK.
    The programming sequence is as follows:
        IFC_CTRL : FSLSSERIALMODE_3PIN ( bti-1) to '1'  -> this will lead to a 3-pin interface.
        IFC_CTRL : CLOCKSUSPENDM ( bit-3) to '0'    ->  the ULPI CLOCK will be stopped.
        OTHER_IFC_CTRL : FSLSSERIALMODE_4pin ( bit 4) to '1' -> Only if  4-pin mode is required.
     
    With above sequence we will not have HS mode.
    Regards
    Ankit