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Ethernet on DM648

Subashini
Prodigy 195 points

 

Hello everyone,

We have a TMS320 DM648 based board. If we connect with emulator and try to access the SGMII or EMAC registers, Code composer disconnects.

If we try to run an ethernet HelloWorld program also, the board prints out the MAC address and then emulator disconnects. All our other tests are running fine except the ethernet test.


We are using a 33 MHz clock input with a PLL multiplier of 27, so running at 891 MHz. The REFCLKP/N is 125 MHz as given in the EVM board. The spruf57 document talks about using a 50 or 62.5 MHz clock, but since we were not booting from network, we are using the 125 MHz clock.

Why do we have this issue with CCS disconnecting on ethernet access?

How can we troubleshoot the issue?

Thanks in advance for all your help.

 

  • 0
    TI__Guru*** 125430 points

    Subashini said:

    The REFCLKP/N is 125 MHz as given in the EVM board.

    Are you talking about the EVM from Lyrtech?  I have that board and the schematics, and it uses a 62.5 MHz REFCLKP/N.  I even looked back at the schematics from the beta version of the board but it also had the 62.5 MHz REFCLKP/N.

    Subashini said:

    The spruf57 document talks about using a 50 or 62.5 MHz clock, but since we were not booting from network, we are using the 125 MHz clock.

    Section 1.4 (Clocks) of spruf57 says, "REFCLKP/N should be between 50-62.5 MHz."

    Subashini said:

    Why do we have this issue with CCS disconnecting on ethernet access?

    How can we troubleshoot the issue?

    How are you configuring the PLL?  It seems like the issue is that your clock is way out of spec and so it's not working.  You will likely need to hack/spin your board.  Also, make sure that you AC couple the REFCLKP/N pins like they do in the EVM.  I've requested that they add a statement about that in the datasheet as well.

  • 0 in reply to Brad Griffis
    Prodigy 195 points

     

    Hello Brad,

     

    We do have the AC couple same as in the EVM schematics. The first set of EVM boards from Lyrtech do have a 125 MHz clock with the MPY field in the CFGPLL register set to 5. We have tried with the 62.5 Mhz clock also. But still have the same issue.

     

    I have another doubt: The datasheet talks abt values for PLLM for the CLKIN1as x1, x15, x20, x25, x30 or x32. The sample program/gel file uses x27 which is different from this set. Is that alright?

     

    Regards

    Suba.

  • 0 in reply to Subashini
    TI__Guru*** 125430 points

    I'm still waiting to hear back on the PLLM values.  I've pinged that team again.  I'll let you know when I hear back.

    Another thing that might be helpful to know would be if you can step through the code and find out exactly where CCS crashes.

  • 0 in reply to Brad Griffis
    TI__Guru*** 125430 points

    I have some other related info for you.  I've heard that it's ok for you to have 125 MHz REFCLK and use x10 mode.  However, if you wish to boot from Ethernet then you need a 62.5 MHz REFCLK.

    Still waiting on the PLL question.

  • 0 in reply to Brad Griffis
    TI__Guru*** 125430 points

    I've received clarification from the DM648 team.   You can use any multiplier value so long as you follow all the specifications in the datasheet, e.g. CLKIN range, PLLOUT frequency, etc.

    EDIT 26 Jan 2009:  You can use PLLM=15 to 31 (i.e. x16 to x32) for your multiplier values, or set PLLCTL.PLLEN=0 for bypass mode (x1).

  • 0 in reply to Brad Griffis
    Prodigy 195 points

    Thanks a lot for your responses.

     

    We also found that the new datasheet has mentioned values for the  ESS_LOCK register to lock or unlock the Ethernet subsystem regs. But we still face the same issue.

     

    Regards

    Suba.

  • 0 in reply to Subashini
    TI__Guru*** 125430 points

    Can you step through your code to narrow down at one point CCS disconnects?