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Hot!KSZ8794 Strap in Options

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LHE
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2017/09/04 01:52:02 (permalink)
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KSZ8794 Strap in Options

Hello community,
 
I am currently designing a system using a KSZ8794 Ethernet switch to add 3 10/100 MBit Ethernet connections to a system.
The KSZ will be interfaced with an NXP MX processor using an RMII interface for now, but I may have to use RGMII later on. I have some questions on the strap in options for the KSZ:
  1.  What values are recommended for pullup/down resistors? Ive seen 1k pulldown and 4k7 pullup recommendations in datasheets of other KSZ devices but cant find anything here. Due to internal PU/PD I probably cant use any value I want.
  2. RMII Mode: Interface mode is selected by LED3[1,0]. Internal Pullups on these pins will default to 11 --> RGMII. If I want RMII, 01 is necessary, so Ill add a pulldown to LED3_1.
  3. MAC/PHY mode: If i understood correctly: MAC mode: SW4 is connected to a Processor/FPGA/... // Phy Mode: connected to an ethernet phy. these options are only available in MII and RMII mode, as these are the only options that would support an external Phy. in RGMII mode, this option is ignored?
  4. What would I need the reference clock for? Id primarily use it for debuging on testhardware (no clock output -> phy not running).
  5. PLL clock source select: why is RMII mode handled differently?
  6. Except for being able to set register 80: what benefits does using SPI provide oder using MDC/MDIO?
    Are the two versions supported with Linux drivers?
Thanks a lot for helping me out, quite a lot of questions.

Regards,
Lars
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2 Replies Related Threads

    glamprecht
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    Re: KSZ8794 Strap in Options 2019/07/22 09:09:30 (permalink)
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    Hello Microchip. Could you answer this please. Currently my searches in the forum reaches 90% of the same questions I have, and less than 10% of those questions are answered by anyone. It is frustrating and driving me crazy, or perhaps to favor other manufacturers first.
    #2
    mbrowning
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    Re: KSZ8794 Strap in Options 2019/07/22 11:04:47 (permalink)
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    This is a user forum. To ask Microchip a question submit a support ticket. And for Ethernet you have the related resource of their "LAN Check service:
    https://www.microchip.com/design-check-services
     

    Go Navy! Beat Army!
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