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DS250DF230: Use retimer to generate and check PRBS signals

user6165069
Prodigy 20 points
Part Number: DS250DF230

Hi:

I'm using DS250DF230 in the design, and I'm doing the PRBS test. The link under test is like this:

Retimer -> SFP -> CABLE -> SFP -> Retimer

I want to use one retimer to generate PRBS, and use the other one to check PRBS. But after I configured the registers, there're no signal detected. My configuration sequence is shown below:

Referenced from Programmer's guide(SNLU182D)

Common Configuration:

0xff       0x03
0x00    0x04
0x0a    0x0c

0x60    0x90
0x61    0xb3
0x62    0x90
0x63    0xb3
0x64    0xff
0x09    0x04
0x18    0x10

0x1e    0xe1
0x31    0x40

0x0a    0x00

Enable generator:
 
0x2e    0x04
0x30    0x01
0x1e    0xf1
0x79    0x10
0x79    0x30
0x30    0x01
0x30    0x09
0xa5    0x80

Enable checker:


0x0d    0x00
0x79    0x50
0x30    0x00
0x30    0x08
0x30    0x18
0x30    0x08
0x82    0x40
0x82    0x00

Any advice will be appreciated, thanks!

  • 0
    TI__Mastermind 19135 points

    Hi,

    The TI retimer implements a reference-less CDR architecture. As such, some valid input signal must be present at the retimer input to be able to generate PRBS pattern. This input pattern is needed to lock the retimer channel CDR to the desired frequency. This reference input signal may be a 1010 clock pattern of a frequency that is a sub-rate of the full rate, and the frequency divide ratio may be as large as 16. For example, to generate 25.78125Gbps PRBS pattern from a retimer channel a 805.664062MHz square wave/sinusoidal signal may be used as the retimer reference input signal. 

    Cordially,

    Rodrigo Natal

    HSSC Applications Engineer

  • 0 in reply to Rodrigo Natal
    Prodigy 20 points

    Hi Rodrigo:

    Thanks a lot! Problem solved! After I give the retimer a signal input, it achieved CDR lock, and it can generate PRBS signal now.

    BR,

    Yuxiao