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EMAC & Gbe switch lenth

David Yang1
Intellectual 435 points

Hi,TI guys:

I am working on PA_multicore Example trying to change it to suit my own application while I encounter a Length problem. There are two relevant registers, Mac Receive mac lenth registers and Port 0 receive lenth Register. Both are configured to 1518. But in the Gbe switch doc, the max lentgh of Mac is 16383, while the Port 0 max receive length is 9504. Since the packet will go through both module from Ethernet to Dsp, why is the value not the same? And what's the maximum receive length of the whole network coproccesser? How shall I set the regiser then?

Looking forward to your answer!

                                                                                                                                                                                                                        Best regards,

                                                                                                                                                                                                                                             David

  • 0
    TI__Intellectual 1585 points

    David,

    There are two places to set max length. EMAC level and CPSW port 0 receive.  They should have the same value of 9500 unless it is with a VLAN header than it would 9504. That would be the max NETCP can take.

     

    Hope this helps!

    Kat

  • 0 in reply to Katherine Kelsch
    Intellectual 435 points

    Hi, Kat

    That answers my question,thank you! Moreover,it there any length limit when sending a packet?  If there is , where to set it & what's the maximum sending length?

     Best regards,

    David

  • 0 in reply to Katherine Kelsch
    Intellectual 435 points

    Hi, Kat,

    Can you through some light on how to set(or is it necessary) the sending length of a packet? And if I use the Gbe as a switch, that is packets go in from mac0 and go out from mac 1 to another equipment. , only port 1&2 are included(correspond to mac0&1). Can the packet reach the max mac length of 16383 In this case?

    Really looking forward to your answer!

    Regards,

    David

  • 0 in reply to David Yang1
    TI__Intellectual 1585 points

    David,

    I suggest getting an EVM or simply getting some example codes in the newest PDK package off the TI website and looking at the included package examples. There are predefined functions that will show the how to set the length of a packet, such as PA_emacExample . The maximum size is a jumbo packet of 9504 (including an header), and these devices are able to take on IPv4 and IPv6 packets.

     I also suggest looking at the Keystone training. They have some slides with examples of what functions to setup the system and how to do it (like NETCP and such): http://focus.ti.com/docs/training/catalog/events/event.jhtml?sku=OLT110027

    You can skip the basic first slides and go to the end where they talk about how to setup a link and others.

     

    Hope this helps!

     

    Kat