DS125DF1610 / recommended register setting for SRIO

Hi Toshiyuki-san,

The 12.5Gbps SRIO specification (Version 3.2) for "Long Channel" electricals includes link training based on 10G-KR Ethernet.  The DS125DF1610 would not support this feature.  The SRIO specification also defines a set of "Short Channel" electricals which does not use link training.  As long as link training is not required the 12.5 Gbps datarate could be supported.

Slower datarate versions of SRIO (up to 6.25 Gbps) did specify the use of non-protocol aware repeaters and retimers like the DS125DF1610.

For 12.5Gbps operation using just the Rate/Subrate table.

0x2F[7:4] = 0111'b (12.5, 6.25, 3.125 Gbps)

To account for 10.3125 Gbps rate as well additional programming is required.

0x2F[7:4] = 0111'b (VCO 1/2/4) 

0x60 = 90'h

0x61 = B3'h

0x62 = 80'h

0x63 = BE'h

0x64 = FF'h

Regards,

Lee

Hi Lee -san,

Thank you for the reply. I have some questions.

Q1

According to SRIO specification [5.11.2.2 Short run 10.3125 and 12.5 Gbaud training], the codeword is 64b/67b. Would DS125DF1610 support  "codeword trainig" or "CW training" under short run ?

Q2

For TI's Retimer, does it matter whether the data encoding is 8b10b, 64b66b, 64b67b or not ?

Q3

Please let me know how to extract the clock in CDR Block.

Best Regards,

Toshiyuki

Hi Toshiyuki-san,

Q1: The DS125DF1610 can support all different encoding or scrambling schemes.  The DF1610 is not protocol aware so any special codewords would be passed upstream or downstream to the system receivers without alteration.

Q2: The encoding does not matter.

Q3: The DS125DF1610 can extract the CDR clock and transmit it on the output by programming the following Channel registers.  

Reg 0x09[5] = 1'b  \\*  Default 0x09 = 00'h  ->  write 20'h

Reg 0x1E[7:5] = 010'b  \\*  Default 0x1E = E9'h  ->  write 49'h

Regards,

Lee