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AR# 65092

CPRI v6.1 - Virtex-6 additional pipeline delay number discrepancy in (PG056)

Description

The CPRI product guide (v6.1) has a discrepancy related to Additional pipeline delays.

Calculating the delays for 4915.2Mb/s data rate using the registers that need be added on page 149 gives 5 Clk cycles of additional delay.

However, the description on page 150 mentions that in Virtex-6, Virtex-7, and Kintex-7 devices, for configurations supporting 4915.2 Mb/s or 6144.0 Mb/s line rates, there are 8 CLK cycles of additional delay.

Solution

This discrepancy is caused by an incorrect description of delays not taking a 4915.2Mb/s line rate.

The descriptions on page 149 need be modified as follows to indicate that linerates of 4915.2Mb/s and above need to be considered instead of line rates above 4915.2Mb/s.

  • One CLK cycle for the cycle that clocks the transmit data into the transceiver.
  • In cores supporting line rates 4915.2 Mb/s and above and in all Artix-7 FPGA based cores, one CLK cycle to clock the data through the transmit multiplexor.
  • One RXRECCLK cycle (Virtex-5 LXT/SXT and Artix-7 devices) or one CLK cycle (Virtex-5FXT/TXT, Virtex-6, Virtex-7, and Kintex-7 devices) for the delay from the output of the transceiver into the CDC FIFO.
    In cores supporting line rates of 4915.2 Mb/s and above, there is one extra CLK cycle, or RXRECCLK cycle in Artix-7 devices, to clock the data out of the transceiver.
  • One CLK cycle for clocking the data out of the CDC FIFO.
  • In cores supporting line rates of 4915.2 Mb/s and above, one CLK cycle, or RXRECCLK cycle in Artix-7 devices, for clocking the data through the descrambler.
  • Two CLK cycles for delay in the control path of the R21 coarse timer.
  • (Virtex-5 LXT/SXT devices only) Three RXRECCLK cycles for delay in converting from 1 byte to 2 bytes.
  • (Artix-7 devices only) Three RXRECCLK cycles for delay in converting from 2 bytes to 4 bytes.
AR# 65092
Date Created 07/29/2015
Last Updated 07/31/2015
Status Archive
Type General Article
IP
  • CPRI