Rx_Buffer_Use; Miscellaneous Signals; Ports And Attributes; Tx_Data_Width - Xilinx RocketIO User Manual

R
RXREALIGN clears this bit.) RXBUFSTATUS[0] High indicates that the elastic buffer is at least
half-full.

RX_BUFFER_USE

When set to FALSE, this attribute causes the receive buffer to be bypassed. It should normally be set
to TRUE, since channel bonding and clock correction use the receive buffer for realignment. When
the buffer is bypassed, the user logic must be clocked with RXRECCLK.

Miscellaneous Signals

Ports and Attributes

Several ports and attributes of the MGT have very unique functionality. The following do not have
large roles in the other functionality discussed so far:
RX_DATA_WIDTH,

TX_DATA_WIDTH

These two attributes define the data width in bytes of RXDATA and TXDATA respectively. The
possible values of each attribute are 1, 2, and 4, which correspond to 8-, 16-, and 32-bit data buses
when 8B/10B encoding/decoding is used. (See
widths are 10, 20, and 40 bits when 8B/10B encoding/decoding is bypassed.

SERDES_10B

This attribute allows the MGT to expand its serial speed range. The normal operational speed range
of 1.0 Gb/s to 3.125 Gb/s (20 times the reference clock rate) is obtained when this attribute is set to
FALSE. When set to TRUE, the MGT serial data will run at 10 times the reference clock rate,
producing a speed range of 622 Mb/s to 1 Gb/s.
Table 2-22: Serial Speed Ranges as a Function of SERDES_10B

TERMINATION_IMP

Receive Termination
On-chip termination is provided at the receiver, eliminating the need for external termination. The
receiver includes programmable on-chip termination circuitry for 50Ω (default) or 75Ω impedance.
Transmit Termination
On-chip termination is provided at the transmitter, eliminating the need for external termination.
Programmable options exist for 50Ω (default) and 75Ω termination.
90
SERDES_10B Reference Clock Range
TRUE
FALSE
www.xilinx.com
1-800-255-7778
Chapter 2: Digital Design Considerations
"8B/10B Encoding/Decoding," page
60 – 100 MHz
50 – 156.25 MHz
RocketIO™ Transceiver User Guide
61.) The bus
Serial Speed Range
600 Mb/s – 1.0 Gb/s
1.0 Gb/s – 3.125 Gb/s
UG024 (v2.3.2) June 24, 2004