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DS125DF111: Retimer initial programming sequence

Abeed Salam
Prodigy 10 points
Part Number: DS125DF111

Tool/software:

We are using the DS125DF111 XFI retimer in our current project. We are having some difficulty programming the retimer.  

Could you please help review the sequence below and let us know if we are missing anything?

This is what we are writing to the register space:

Register

Value

R/W

Reason

0xFF

0x0C

W

Broadcast to all channel

0x0A[3:2]

0x1C

W

CDR reset override

W

Enable CDR reset override

0x60

0x00

W

VCO frequency settings

0x61

0xB2

W

0x62

0x90

W

0x63

0xB3

W

0x64

0xCD

W

0x0A[3:2]

0x1

W

Release CDR reset

Do we need to write back to 0xFF register space anything at the end to get the retimer to lock to the input?

  • 0
    TI__Mastermind 18850 points

    Hi Abeed,

    Your register write sequence generally looks good and I don't see any major issues. I do have a few comments.

    • Your VCO configuration selects data rates 10 Gbps and 10.3125 Gbps. Were these your intended selections?
    • We typically recommend using 0x64=0xFF to increase the PPM threshold for CDR lock. I don't expect this to make a big difference compared to 0x64=0xCD.
    • There may be a typo on your last line. Can you confirm you are writing 0x0A=0x10 to release CDR reset?

    You do not need to write back to register 0xFF at the end of your sequence.

    • Are you having trouble obtaining CDR lock?
    • Can you share the data rate and pattern being transmitted to the retimer?

    Best,

    Lucas