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USB-2-MDIO: USB-2-MDIO Very Slow Response

Dominic Lisi
Prodigy 70 points
Part Number: USB-2-MDIO
Other Parts Discussed in Thread: MSP-EXP430G2ET

Good Morning,

I'm using the USB-2-MDIO tools on a windows 10 machine and the response time is incredibly slow. It takes ~20 seconds for each access to take place. I have the MDIO and MDC signals on an oscilloscope and I see that the transaction happens instantly, and correctly (and only once as expected). But it takes a very long time for the result to populate back to the GUI.

It's even worse when I run a script with several (~10) accesses. It takes almost 5 minutes to get the data back. Every 20 or 30 seconds I see the green and red LEDs flash once as if it's doing another access.

I'm using the latest SW, drivers, etc with a MSP-EXP430G2ET launch pad

I'm talking to a Marvell Switch, but I'm not sure if that has anything to do with it, like I mentioned before the accesses happen instantly and correctly.

Thanks

  • 0
    TI__Genius 11900 points

    Hello Dominic,

    Thanks for letting us know about this issue.

    Do you see the same issues with a TI PHY EVM?

    Thanks,

    Vibhu

  • 0 in reply to Vibhu Vanjari
    Prodigy 70 points

    Thanks for the response.

    Unfortunately I don't have an eval board to use. 

    The only other information I have is that if I reconnect/power on the launch pad and re-open USB2-MDIO the first script access runs in a normal, quick, time frame. After that it's always slow. Correct, but very slow

  • 0 in reply to Dominic Lisi
    TI__Genius 11900 points

    Hello Dominic,

    Not having access to TI PHY EVM makes things difficult with the information provided. I do not believe there are issues with the MDIO software when interfacing with a TI PHY. Is it possible that the software was not downloaded setup right? Can you attempt to re-download and setup the software?

    Thanks,

    Vibhu

  • 0 in reply to Vibhu Vanjari
    Prodigy 70 points

    Well, I accidently clicked this resolved my issue - but it didn't.

    I don't have access to the EVM, however I do have a custom board with a DP83867ISRGZ phy on it, and it exhibits the same problem.

  • 0 in reply to Dominic Lisi
    TI__Genius 11900 points

    Hello Dominic,

    Can you confirm that you are using the right pull-up resistor as mentioned in the datasheet? With 1% tolerance.

    Thanks,

    Vibhu

  • 0 in reply to Vibhu Vanjari
    Prodigy 70 points

    I have a 2.2KOhm Resistor on the MDIO line on both MDIO ports (switch and TI Phy)

    I think it's some sort of issue with the USB2-MDIO software. 

    If I close the SW and re-open it, my script with ~15 commands, or even a single GUI command, executes about once per second, which is fairly reasonable. Anything I do after that takes ~30 seconds per command. My solution is just to close/open the SW between any accesses or scripts.

  • 0 in reply to Dominic Lisi
    TI__Genius 11900 points

    Hello Dominic,

    There should be only one pull-up resistor of that value on the MDIO line. Are these ports configured in a way that the pull-up resistors would be in parallel with each other? If so can you also check to see what happens when one of these in DNP'd?

    As far as your issue goes, this isn't a common problem, and the software works fine with our EVMs.

    Thanks,

    Vibhu

  • 0 in reply to Vibhu Vanjari
    Prodigy 70 points

    The two MDIO busses that I'm testing are independent, so the resistors aren't in parallel.

    Unfortunately I don't really have the time to debug this issue right now. Restarting the software works for my needs.

    That being said, I don't understand how the pullup resistors could change this behavior. I can run a script with over 20 commands after starting the software and it's fine. Any other access after this and it's very slow.