IODELAY_GROUP - 2023.1 English

IODELAY_GROUP groups IDELAYCTRL cells together with their associated IDELAY and ODELAY cells to allow proper placement and replication.

If you use IODELAY_GROUP to assign a group name to an IDELAYCTRL, you need to also associate an IDELAY or ODELAY cell to the group using the same IODELAY_GROUP property.

Important: While an IODELAY_GROUP can contain multiple cells, a cell can only be assigned to one IODELAY_GROUP. For automatic placement purposes, each bank can only be assigned a single IODELAY_GROUP.

The following example uses set_property to group all the IDELAY/ODELAY elements associated with a specific IDELAYCTRL.

set_property IODELAY_GROUP IO_DLY1 [get_cells MY_IDELAYCTRL_inst] 
set_property IODELAY_GROUP IO_DLY1 [get_cells MY_IDELAY_inst] 
set_property IODELAY_GROUP IO_DLY1 [get_cells MY_ODELAY_inst]

Difference Between IODELAY_GROUP and HIODELAY_GROUP

IODELAY_GROUP can group elements across different hierarchies, whereas HIODELAY_GROUP names are made unique per hierarchy. Use IODELAY_GROUP to group I/O delay components from different hierarchies into a single group.

HIODELAY_GROUP groups I/O delay components under the same hierarchical module.

Architecture Support

All architectures.

Applicable Objects

Cells (get_cells)
- IDELAY, ODELAY, or IDELAYCTRL instances

Values

Any specified group name.

Syntax

Verilog Syntax

Place the Verilog attribute immediately before the instantiation of an IDELAY, ODELAY, or IDELAYCTRL.

(* IODELAY_GROUP = "value" *)

Verilog Syntax Example:

// Specifies a group name of DDR_INTERFACE to an instantiated IDELAYCTRL
// IDELAYCTRL: IDELAYE2/ODELAYE2 Tap Delay Value Control
//	Virtex-7
// Xilinx HDL Language Template, version 2014.1
// Specifies DDR_INTERFACE group name for IDELAYs/ODELAYs and IDELAYCTRL (* IODELAY_GROUP = “DDR_INTERFACE” *)
IDELAYCTRL DDR_IDELAYCTRL_inst (
.RDY(),	// 1-bit output: Ready output
.REFCLK(REFCLK), // 1-bit input: Reference clock input
.RST(1’b0)	// 1-bit input: Active-High reset input
);
// End of DDR_IDELAYCTRL_inst instantiation

VHDL Syntax

Declare the VHDL attribute as follows:

attribute IODELAY_GROUP : string;

For an instantiated instance, specify the VHDL attribute as follows:

attribute IODELAY_GROUP of instance_name : label is "group_name";

Where instance_name is the instance name of an instantiated IDELAY, ODELAY, or IDELAYCTRL.

VHDL Syntax Example:

// Specifies a group name of DDR_INTERFACE to an instantiated IDELAYCTRL attribute IODELAY_GROUP : STRING;
attribute IODELAY_GROUP of DDR_IDELAYCTRL_inst: label is "DDR_INTERFACE"; begin
-- IDELAYCTRL: IDELAYE2/ODELAYE2 Tap Delay Value Control
--	Virtex-7
-- Xilinx HDL Language Template, version 2014.1 DDR_IDELAYCTRL_inst : IDELAYCTRL
port map (
RDY => open,	-- 1-bit output: Ready output
REFCLK => REFCLK, -- 1-bit input: Reference clock input RST => ‘0’	-- 1-bit input: Active-High reset input
);
 

-- End of DDR_IDELAYCTRL_inst instantiation

XDC Syntax

set_property IODELAY_GROUP group_name [get_cells instance_name]

Where

group_name is a user-specified name for the IODELAY_GROUP.
instance_name is the instance name of an IDELAY, ODELAY, or IDELAYCTRL.

XDC Syntax Example:

# Specifies a group name of DDR_INTERFACE to an instantiated IDELAYCTRL 
set_property IODELAY_GROUP DDR_INTERFACE [get_cells DDR_IDELAYCTRL_inst]

Affected Steps

Placement