116 www.xilinx.com Virtex-4 RocketIO MGT User GuideUG076 (v4.1) November 2, 2008Chapter 3: PCS Digital Design Considerations RSymbol Alignment and Detection (Comma Detection)SummaryIn addition to 8/10-bit symbol alignment detection, the RocketIO MGT has been expandedto detect and align to 32-bit boundary to support A1, A2 sequences of SONET applications.The 32-bit SONET aligner was designed specifically for SONET and might not be suitablefor generic applications. The ability to detect symbols, and then align either to 1-, 2-, or 4-word boundaries is included. The traditional alignment block has the RXSLIDE input thatallows the user to slide or slip the alignment by one bit in each 32- and 40-bit mode at anytime when any applications cannot be supported with the SONET or 10-bit commadefinitions.The following ports and attributes affect the function of the comma detection block:• RXCOMMADETUSE• ENMCOMMAALIGN• ENPCOMMAALIGN• ALIGN_COMMA_WORD[1:0]• MCOMMA_32B_VALUE[31:0]• MCOMMA_DETECT• PCOMMA_32B_VALUE[31:0]• PCOMMA_DETECT• COMMA_10B_MASK[9:0]• RXSLIDE• RXINTDATAWIDTH[1:0]• COMMA32• PMA_BIT_SLIP• RXSYNCBypassingComma detection is disabled when RXCOMMADETUSE is set to logic 0.If RXCOMMADETUSE is set to logic 1, symbol/comma detection takes place.See Table 3-8.Table 3-8: Deserializer Comma Detection BypassSignal FunctionRXCOMMADETUSE0 Comma detection is disabled.1 Comma detection is enabled. COMMA is detectedbased on Table 3-9.ENPCOMMAALIGNENMCOMMAALIGN00 Comma alignment is disabled. RXDATA reflects howthe data is output from the deserializer.01Comma alignment is enabled. The comma is definedby COMMA_10B_MASK andMCOMMA _32B_VALUE.10Comma alignment is enabled. The comma is definedby COMMA_10B_MASK andPCOMMA _32B_VALUE.11Comma alignment is enabled. The comma is definedby COMMA_10B_MASK and MCOMMA_32B_VALUE, PCOMMA_32B_VALUE.
