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TLK110 restart in RMII/MII mode

Felickao Yang
Intellectual 650 points
Other Parts Discussed in Thread: TLK110, TLK111

I'm working with a TLK110 and would like to know if it's possible to switch between RMII and MII mode using the PHY register access. I do not want to use the pin strap or the software strap configuration (SWSC). In my application, I will startup in RMII mode, but depending on the configuration, I may have to use MII. Is it possible to change between RMII and MII mode using only the PHY's registers. According to the datasheet (slls901c.pdf) the RMII Control and Status Register (RCSR, register 0x0017) bit 5 is the RMII Mode. Is it possible to use this bit to toggle between RMII and MII mode? Does this take affect immediately or do I have to reset the PHY? Which reset would I use? The BMCR bit 15 is a Reset. The PHYRCR register has two resets: bit 15 is a Software Reset, and bit 14 is a Software Restart (resets all PHY circuitry except the registers). It appears that PHYRCR bit 14 will maintain my register settings for RMII or MII mode, but I would like to know if anyone else has more information regarding this setup.

  • 0
    Intellectual 650 points

    According to a post by Sun Kim on http://e2e.ti.com/support/interface/ethernet/f/903/t/268043.aspx, he claims that "RMII mode negotiation only can be done with hardware MII_MODE bootstrap!" However his solution is self verified. Can a TI moderator or TI employee confirm whether or not this is the only method of configuring MII or RMII mode? If  there are other methods of configuring MII or RMII mode, I would appreciate any information.

  • 0 in reply to Felickao Yang
    TI__Intellectual 1500 points

    Hi,

    Sorry for the delayed response.
    As you described, RMII Control and Status Register (RCSR, address 0x0017, bit 5) can control the MII / RMII modes
    (Bit 5: '1' = Enable RMII mode of operation, '0' = Enable MII mode of operation).
    RMII Mode is operational if device powered up in RMII mode (pin_strap) and 50 MHz clock present.
    Please note, that in order to switch from RMII to MII and vise versa, the PHY must initialize after power up in RMII mode (Strap is '1' and REF_CLK is 50 MHz). If the PHY initializes in MII mode, this bit has no effect.
    If the described method is followed, no PHY reset is required.

    Thanks,
    Noam

  • 0 in reply to Noam Sadan
    TI__Intellectual 1720 points

    Hello,

    Furthermore,

    We have updated the TLK111 data sheet with this information (page 71): http://www.ti.com/lit/ds/symlink/tlk111.pdf

    TLK110 DS will be updated in the same manner soon (same functionality)

    Bottom-line: the duality work of RMII and MII using only register access is feasible:

    1) Need to start with RMII (strap and 50MHz)

    2) When moving to MII mode (with the register bit [5] , RCSR) still keep the 50 MHz clock as input

    3) It is recommended is possible to apply software reset after the change (reg X001F, PHYRCR)

    Thanks & Regards,

    Oren