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I'm working on connecting the LXT972M PHY Transceiver to LPC2368 chip. I've already done the RMII to MII converter, but I can't figured how to implement that bidirectional MDIO signal in VHDL. As I just spotted it must be managed by some additional signal, but which? Is it really necessary to using that MDIO?

SebastianKupisDev
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  • You can look in IEEE Std 802.3-2008 section 2. Information sufficient to to design an MDIO state machine can be found in the LXT972M datasheet, 5.2.3.1.2 MDIO Frame, Figures 3/4 Management Interface Read/Write Frame Structure, where STA or PHY driving MDIO during the data field of a management frame is determined by opcode. You can set the configuration manually, see datasheet 5.44 Hardware Configuration Settings. Is this a programming question or a design question? –  Jul 31 '15 at 18:44
  • Here's an examplr of a [MDIO serial control interface](https://raw.githubusercontent.com/gmarescotti/domotica/master/mdio.vhdl) state machine in VHDL. –  Jul 31 '15 at 19:12
  • [Wikipedia](https://en.m.wikipedia.org/wiki/Management_Data_Input/Output) provides a nice and comprehensive article on MDIO (incl. waveforms). It's like I2C. Some PHYs can also be configured via I2C by setting a jumper or config pin. – Paebbels Jul 31 '15 at 20:09
  • Thank You for answering me, but in my scenario there is only MDC clock signal that comes from lpc board to phy, and that bidirectional MDIO. Do I actually need that 16 bit vectors? Which signal should I use to root the data? – SebastianKupisDev Aug 03 '15 at 18:22

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