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Which Tools Can I Use to Read and Write MDIO Protocol Signals?
Rena Ayeras

Image by Dmitriy from Pixabay

Question from the Customer:

I am looking for a host to write and read MDIO protocols per IEEE 802.3u clause 22.

Which devices and software applications do you recommend?

Response from Technical Support:

Thank you for your question! In general, our tools do not have explicit MDIO support. However, if your requirements are for a general-purpose device, then we have two recommendations: the Promira Serial Platform and the Beagle I2C/SPI Protocol Analyzer.

Actively Read and Write MDIO

With the Promira platform, you can control each individual signal by emulating MDIO through the SPI or GPIO lines. You can use the signal lines as follows:

  • Drive an MDC clock signal, which is similar to the SPI clock.
  • Use a bidirectional GPIO line for the MDIO signal.

The Promira platform, licensed with an I2C application, I2C Active - Level 1 or Level 2 Application, supports those features.

We also recommend using Promira Software API I2C/SPI Active for developing a custom application. This way, you can program two of the GPIO pins to generate the MDC clock and control the bidirectional MDIO data. Effectively, you would be emulating an MDIO Master. There is a limitation to be aware of: with a software-driven clock signal, you can only control the clock edges, not the durations of the low and high signal periods of the clock.

For an overview of all the features of the Promira platform, please take a look at this data sheet.

Non-intrusively Monitor MDIO

If monitoring and analyzing data is part of the job, we recommend the Beagle I2C/SPI Protocol Analyzer, a non-intrusive bus monitor. This Beagle I2C/SPI analyzer can monitor MDIO - as specified by IEEE 802.3u clauses 22 and 45 - up to 2.5 MHz, as well as SPI data up to 24 MHz, and I2C up to 5 MHz.

Please note, for monitoring MDIO traffic, download and use Data Center software v2.20 with the Beagle I2C/SPI analyzer. Alternatively, you can use Beagle Software API to create a more customized script, specific to your system requirements. For information about the API commands, refer to the MDIO API section of the Beagle Protocol Analyzer User Manual. Also, functional scripts are provided with the API, which can be used as is, or modified as needed.

Please note, to accurately capture MDIO signals, the sampling rate must be set properly. For MDIO monitoring, the minimum requirement for the sampling rate is twice the bus bit rate.

Here are the hardware interfaces for MDIO signals:

  • Pin 8 is the management data input/output. This signal is bidirectional, which is used to transfer data between the STA and the MMD.
  • Pin 7 is the management data clock. This is a control line that is driven by the STA and synchronizes the flow of the data on the MDIO line.
  • The Beagle analyzer signal level is 3.3V. To monitor a lower voltage MDIO bus, you can use the Level Shifter Board.

For an overview of all the features of the Beagle I2C/SPI Protocol Analyzer, please refer to this data sheet.

We hope this answers your questions. Additional resources that you may find helpful include the following:

If you want more information, feel free to contact us with your questions, or request a demo that applies to your application.