I'm working with Realtek's RTL8367 switch IC.

Background: I am having trouble with throughput being unbalanced. If I run iperf between two ports in one direction I get a different throughput if I run iperf in the opposite direction. Differences are between 500 Mbps and 800 Mbps, which are significant in my application.

To help me determine why this may be happening, I've decided to try to look at the registers in the 8367. I'm hoping that there will be some indication in the registers that will help me resolve this curious imbalance. Note that the switch IC is on a board that does not have a processor.

To that end, I need to interface with the part via what the data sheet calls SMI interface. From what I am able to tell, this is the I2C interface but with extra clocks on either end of the communication packet.

I've already attempted reading the registers using a FTDI 232H cable cpnnected to the SCK/SDA pins. This does not appear to be working and from what I can tell this is due to the 232H part generating glitches on the clock.

Through my searching, I've come across many places where the claim is that the terms SMI, MDIO and MIIM are all different names for the same interface. Here's one example.

But, the timing diagrams for that interface, as shown in the link, are not similar to those shown in the data sheet. This leads me to wonder if these acronyms are really interchangeable.


A) Are the interface terms SMI, MDIO and MIIM truly interchangeable?

B) What type of hardware device/tool would you recommend I use as an outboard interface to this part?

C) Does anyone know of any utilities that could be used 'off the shelf' to read these registers?

Thank you in advance for your time and comments.

  • 1
    \$\begingroup\$ An Arduino with bit banged interface will do the trick. Make sure your voltages and resistors are correct. As for a utility, unless Realtek provides you with one, there is probably no such thing available. \$\endgroup\$ – Lior Bilia Feb 28 at 15:27

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