Virtex-4 RocketIO MGT User Guide www.xilinx.com 331UG076 (v4.1) November 2, 2008Pre-emphasis, Differential Swing, and EqualizationRRXSTATUS BusSeveral buses have changed over the generations to improve the information that isindicated. Table E-9 shows the migration from Virtex-II Pro to Virtex-II Pro X and finallyVirtex-4 devices.Pre-emphasis, Differential Swing, and EqualizationThe differential signaling techniques have continued to get more robust throughout theMGT devices. Table E-10 shows the migration of attributes from Virtex-II Pro toVirtex-II Pro X and finally Virtex-4 devices.Table E-9: Status Bus ChangesDescription Virtex-II Pro Virtex-II Pro X Virtex-4Indicates channel bondingcomplete. CHBONDONE (1) CHANBONDDONE RXSTATUS[5]Indicates status bus is status,data, event. N/A RXBUFSTATUS[1:0] RXSTATUS[4:3]Indicates channel bonding orclock correction pointers change. RXCLKCORCNT RXCLKCORCNT[2:0] RXSTATUS[2:0]Indicates that an RX buffer hasunder/overflown. RXBUFSTATUS[1] N/A(2) RXBUFERRNotes:1. RXCLKCORCNT must go to 3'b101 before channel bonding is complete.2. Logic can be implemented in the fabric to indicate an under/over flow.Table E-10: Signal Optimization AttributesDescription Virtex-II Pro Virtex-II Pro X Virtex-4Controls TX pre-emphasis and edge rate TX_PREMPHASIS TXEMPHLEVELTXPRE_PRDRV_DACTXPRE_TAP_PDTXSLEWRATETXPOST_PRDRV_DACTXDAT_PRDRV_DACTXPOST_TAP_PDControls differential amplitude of thetransmitted signal TX_DIFF_CTRL TXDOWNLEVELTXPRE_TAP_DACTXPOST_TAP_DACTXDAT_TAP_DACActive equalization N/A RXFER RXAFEEQ
