R21 Calculation - 8.11 English

CPRI LogiCORE IP Product Guide (PG056)

Document ID
PG056
Release Date
2022-11-16
Version
8.11 English

To calculate the cable delay for a particular link instance, measure or infer the frame timing at the output and input of the master (in the case of T 14 ) and at the input and output of the slave (in the case of T offset ). Use the T 14 and T offset times to calculate cable delay, as described in section 4.2.9 of the CPRI Specification v7.0 [Ref 1] .

The general procedure for calculating T 14 or T offset is:

1. Measure the coarse value using the R21 Coarse Timer.

2. Correct the coarse value for delays between the timer and the pins of the transceiver.

For 8b10b line rates: 16-bit datapath cores, one datapath clock equates to 20 UI and for 32-bit datapath cores, one datapath clock equates to 40 UI.

For 64b66b line rates: 32-bit datapath cores, one datapath clock equates to 33 UI and for 64-bit datapath cores, one datapath clock equates to 66 UI.