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DS250DF410: ds250DF410 Eval Board PRBS Generator

Part Number: DS250DF410
Other Parts Discussed in Thread: , SIGCONARCHITECT

Dear e2e

I read some note for how to make DS250DF410 output  PRBS data and I saw the answer from the

url:https://e2e.ti.com/support/interface/high_speed_interface/f/138/t/512000?tisearch=e2e-quicksearch&keymatch=DS250DF410

is the answer means that:

to get the PRBS data output I should be input clock to RX channel?

if not clould you tell me how to get PRBS data output and tell me if I want to get a eye diagram,what should  I do(I have the DS250DF410EVM)?

Thank you.

kailin.zhao

  • Hi Kailin,

    I did read Rodrigo's comment as well.

    You are correct. Input to RX channel either has to be 25GbE PRBS data or a clock at subrate of 25GbE. For example, you can apply 12.5G clock 1010.. pattern - sub-rate of 25GbE data - and device would lock to this pattern.

    Regards,,nasser
  • Hi nasser

    if I Input a 12.890625GHz sine wave to RX0 Channel,Could me get a PRBS31 data output from TX2 Channel?
  • Hi nasser

    if I Input a 12.890625GHz sine wave to RX0 Channel,Could me get a PRBS31 data output from TX2 Channel(data rates is 25.78125Gbps)?
  • Hi Kailin,

    You can get PRBS31 on output of the adjacent channel as long as they share the same cross point. For example, you can do this on channel 0 &1. Or channel 2&3. But this cannot be done on channel 0&2 for example.

    Also, please make sure adjacent channel CDR is locked before setting up PRBS generator registers.

    Regards,,nasser
  • HI Nasser,

    I am test DS250DF410 using DS250DF410EVM,I input a sine wave to RX0 and I want to get PRBS31 data output from TX1,is the connection correct?
    I choose lane crossing in crossing switch,Pattern Generator and PRBS Generator in CDR,Enable PRBS Generator in Prbs Generator Table,is that correct?

    In general, I want to get PRBS output, I try a lot but I could not get PRBS output!

    thanks
  • Greetings Kailin,

    Please below note steps to generate PRBS pattern as you had requested:

    1). Sine Wave Frequency: Please make sure your sine wave frequency is divide by 2, 4, or 8 of the desired PRBS pattern frequency. For example, i am using 6.25GHz clock to generate 25G PRBS pattern. Also, make sure peak to peak level is about 500mV differential.
    2). Connect clock signal as noted above to RXP0 and RXN0
    2). Go to CDR tab, and make sure 25Gbps is selected for channel 0 and then click Apply to All Channels button - using SigconArchitect software
    3). Go to "Device Status" tab and make sure Signal is detected and CDR is locked for RX0 or channel 0.
    4). Go to Crosspoint Switch and configure the followings:
    Pair Select = Pair 0
    Crosspoint Mode = Fanout
    Broadcast Channel = Channel 0
    Once these are selected, click on Broadcast button
    5). On Crosspoint Switch tab confirm Channel 1 Signal Detected and CDR Lock LEDs are both green
    6). Go to PRBS Gen/Checker tab:
    a). Channel Select = Channel 1
    b). PRBS Pattern Type = Use desired PRBS pattern for example PRBS10
    c). Click on PRBS Generator Configuration Enable button. You should see current consumption by 100mA or so.
    7). Connect TXP1 and TXN1 to RXP3 and RXN3. Once this connection is made you should see current consumption go up by about 200mA. Overall current consumption should be about 700 to 750mA.
    8). Next go to Device Status tab and you should see channel 0, channel 1, and channel 3 Signal Detect and Lock Detected LEDs green

    Regards,,nasser
  • Hi nasser

    I followed your step,Step 1 to Step 5 and everything is OK. but when I followed step 6-c,the software give me a warnning. 

    "Device supports maximum of 2 PRBS blocks",what does it mean and how to solve this problem?

  • many thanks to you,I have got PRBS data out.

    and How to solve the rise edge and fall edge undershoot?

  • Hi Kaiin,

    It is possible that you may have selected multiple channels to generate PRBS pattern and you can have at maximum 2 PRBS generator per quad device.

    I just tried this again and used the same exact software you are using - DS250DF410 - and am not able to duplicate what you are reporting.

    Please review the instructions and check again. It seems you are selecting more than 2 PRBS generators. However, I don't know how you could be doing this.

    Also, actually you can use channel 0 to generate PRBS and then connect this to channel 1. Given this, you don't need to change cross point settings. Please this as well and let me know.

    Regards,,nasser

  • Hi nasser

    There is anather problem.I can get 25Gbps and 25.78Gbps,PRBS31 data output.But I can't get 24.33Gbps data output,Is this device support 24.33Gbps data output?

    thank you
  • Hi Kailin,

    Please note DS250DF410 programming guide section 6.7 (Manual Data Rate Configuration). You need to calculate values register values to enable the device to lock to 24.33Gbps data rate.

    Additionally, you need to provide integer multiple of 24.33MHz clock to get PRBS generator to work. Could you please let us know your application for 24.33Gbps? 

    Please note I am going to close this thread since this is a new question. If needed you can open a new case.

    Regards,,nasser

  • Kailin,

    One more note regarding 24.33Gbps operation.

    You can use SigconArchitect, go to CDR tab, and enable Manual Mode. After entering data rate - 24.33Gbps - this GUI computes register values for Reg 0x60 through 0x67. Then go to low level and note reg 0x60 through reg 0x67. These are the values needed to enable the device to lock to 24.33Gbps data rates.

    Regards,,nasser
  • Hi nasser

    24.33Gbpbs is used for Common Public Radio Interface(CPRI).You could read the definitions from:http://www.cpri.info/definitions.html

    thank you

  • Hi Kailin,

    I thought i had already answered this question however i see this thread is still open.

    Here is a link to an FAQ describing procedures to do this:
    e2e.ti.com/.../702678

    Regards,,nasser