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Problem with MAC Address Modification on TM4C129XL using EMAC Driver Library

Mark LoBuono
Intellectual 500 points


Using the DriverLib/EMAC I have a functioning Broadcast UDP Transmitted Message with one problem. The second octet of the Destination MAC Address is changing from FF-FF-FF-FF-FF-FF (programmed value) to FF-00-FF-FF-FF-FF when viewed on wireshark on my computer. I have no idea why this is happening. The Ethernet - IP - UDP frames, lengths and format are correct.

Any ideas of where to look?

Does any one know the proper configuration of the MAC and PHY registers for Transmitting UDP Messages?

Of course, the TI example code gave no explanations of the setup used. I have spent 4 days figuring out what I think is the proper configuration. If TI would have spent more time with useful examples of how to use the product that would alleviate a lot of customer frustration.

The TM4C129XL evaluation board has amazing performance and I would like to use this TI Processor. If I cannot solve this I will move on to another manufacturer.

  • 0
    TI__Guru**** 244400 points
    Hello Mark,

    Most users using the TM4C129x series for ethernet rely on the TI RTOS solutions or the lwIP software stack to be able to implement the applications. We have seen one post on the forum for a driverlib based solution but from "understanding" ethernet perspective. Now while it is a good idea, re-inventing the TCP/IP or UDP stack is a massive task (just take a look at the number of contributors on lwIP site).

    Now having set a context to why not every permutation-combination example may not always be possible, let us look at the issue on-hand. The issue is that the Destination MAC address is not getting transmitted. The frame is formed in the SRAM and the EMAC DMA picks it up and packages it in the ethernet frame. The first thing to check is if the address in SRAM is correct and is not corrupted. The second information to check is the TDES Status returned by the MAC controller to see which if any error bit or completion bits are set.

    Regards
    Amit
  • 0 in reply to Amit Ashara
    Intellectual 500 points

    I tried the both the Tiva C lwip and TI-RTOS lwip and could not find ONE good example, anywhere, of how to perform UDP Communications!

    This is the most frustrating part of trying to use this product.

    Do you know where I can find a good example of how to do lwip udp communications. If you say no, then why would you suggest I try using lwip?

  • 0 in reply to Mark LoBuono
    TI__Guru**** 244400 points
    Hello Mark

    There is a udp_echo example in TI RTOS for TM4C129x devices. It is one of the predefined examples.

    Regards
    Amit