Xilinx RocketIO User Manual

Also see for RocketIO: User guide User guide User guide

Contents

Xilinx RocketIO User Manual Manual pdf 70 page image

70 www.xilinx.com RocketIO™ Transceiver User GuideUG024 (v3.0) February 22, 2007Chapter 2: Digital Design ConsiderationsRPCOMMA_DETECT,MCOMMA_DETECTThese two control attributes define when RXCOMMADET signals that a comma has beenreceived. When only PCOMMA_DETECT is TRUE, RXCOMMADET signals when a plus-comma is received, but not a minus-comma. When only MCOMMA_DET is TRUE,RXCOMMADET signals when a minus-comma is received, but not a plus-comma. If bothattributes are TRUE, RXCOMMADET will signal when either comma character is received.COMMA_10B_MASK,PCOMMA_10B_VALUE,MCOMMA_10B_VALUEThe RocketIO transceiver allows the user to define a comma character using these threeattributes. The COMMA_10B_MASK bits are used in conjunction withPCOMMA_10B_VALUE (to define a plus-comma) or MCOMMA_10B_VALUE (to define aminus-comma) to define some number of recognized comma characters. High bits in themask condition the corresponding bits in PCOMMA_10B_VALUE orMCOMMA_10B_VALUE to matter, while Low bits in the mask function as a “don’t care”conditioner.For example, with COMMA_10B_MASK set to 1111111000 (meaning the three leastsignificant bits don’t matter) and PCOMMA_10B_VALUE is 0011111000, the commadetection unit will recognize the following characters as plus-commas:0011111000 (K28.7)0011111001 (K28.1)0011111010 (K28.5)0011111011 through 0011111111 (not valid comma characters)Using the same value in PCOMMA_10B_VALUE but setting COMMA_10B_MASK to1111111111 (meaning all the bits in PCOMMA_10B_VALUE matter), the commadetection unit will recognize only the 0011111000 (K28.7) sequence, which matches thevalue of PCOMMA_10B_VALUE exactly.DEC_PCOMMA_DETECT,DEC_MCOMMA_DETECT,DEC_VALID_COMMA_ONLYThese signals only pertain to the 8B/10B decoder, not the comma alignment circuitry. TheDEC_PCOMMA_DETECT and DEC_MCOMMA_DETECT control the 8B/10B decoder tosignal the RXCHARISCOMMA port if a plus-comma or minus-comma is received. This isdescribed in the table below.DEC_VALID_COMMA_ONLY, for most applications, should be set to TRUE. If valid datais being transmitted and hence received, then an invalid comma would arise only in thecase of a bit error, in which case RXCHARISCOMMA would not be asserted in thepresence of bit errors. If set to FALSE, then RXCHARISCOMMA will be asserted forinvalid K-characters.RXREALIGNThis status signal indicates whenever, the serial data is realigned from a comma characterin the data stream. This signal will not necessarily go High after the transceiver is reset. IfProduct Not Recommended for New Designs