Iserdes_Nodelay Attributes; Bitslip_Enable Attribute; Data_Rate Attribute - Xilinx Virtex-5 FPGA User Manual

Chapter 8: Advanced SelectIO Logic Resources
frequency domain. Therefore, RST should be driven High for a minimum of one CLKDIV
cycle.
When building an interface consisting of multiple ISERDES_NODELAY ports, all
ISERDES_NODELAY ports in the interface must be synchronized. The internal retiming of
the RST input is designed so that all ISERDES_NODELAY blocks that receive the same
reset pulse come out of reset synchronized with one another. The reset timing of multiple
ISERDES_NODELAY ports is shown in

ISERDES_NODELAY Attributes

Table 8-2
description of each attribute follows the table. For more information on applying these
attributes in UCF, VHDL, or Verilog code, refer to the Xilinx ISE Software Manual.
Table 8-2: ISERDES_NODELAY Attributes
Attribute Name
BITSLIP_ENABLE Allows the user to use the Bitslip submodule
or bypass it. See
Attribute."
DATA_RATE Enables incoming data stream to be
processed as SDR or DDR data. See

"DATA_RATE Attribute."

DATA_WIDTH Defines the width of the serial-to-parallel
converter. The legal value depends on the
DATA_RATE attribute (SDR or DDR). See
"DATA_WIDTH Attribute."
INTERFACE_TYPE Chooses the ISERDES_NODELAY use
model. See
NUM_CE Defines the number of clock enables. See
"NUM_CE Attribute."
SERDES_MODE Defines whether the ISERDES_NODELAY
module is a master or slave when using
width expansion. See
Attribute."

BITSLIP_ENABLE Attribute

The BITSLIP_ENABLE attribute enables the Bitslip submodule. The possible values are
TRUE and FALSE (default). BITSLIP_ENABLE must be set to TRUE when
INTERFACE_TYPE is NETWORKING and FALSE when INTERFACE_TYPE is MEMORY.
When set to TRUE, the Bitslip submodule responds to the BITSLIP signal. When set to
FALSE, the Bitslip submodule is bypassed. See
DATA_RATE Attribute
The DATA_RATE attribute defines whether the incoming data stream is processed as
single data rate (SDR) or double data rate (DDR). The allowed values for this attribute are
SDR and DDR. The default value is DDR.
358
summarizes all the applicable ISERDES_NODELAY attributes. A detailed
Description
"BITSLIP_ENABLE
"INTERFACE_TYPE Attribute."
"SERDES_MODE
www.xilinx.com
Figure 8-9, page 365.
Value
Boolean: "TRUE" or "FALSE"
String: "SDR" or "DDR"
Integer: 2, 3, 4, 5, 6, 7, 8, or 10.
If DATA_RATE = DDR, value is
limited to 4, 6, 8, or 10.
If DATA_RATE = SDR, value is
limited to 2, 3, 4, 5, 6, 7, or 8.
String: "MEMORY" or
"NETWORKING"
Integer: 1 or 2
String: "MASTER" or "SLAVE"
"BITSLIP Submodule."
Virtex-5 FPGA User Guide
UG190 (v5.0) June 19, 2009
Default
Value
FALSE
DDR
4
MEMORY
2
MASTER