The Input Output Block Delay (IOBDELAY) property specifies whether to add or remove delay in the ILOGIC block to help mitigate input hold times for system-synchronous data input capture.
The ILOGIC block is located next to the I/O block (IOB), and contains the synchronous elements for capturing data as it comes into the FPGA through the IOB. The ILOGIC block in 7 series FPGAs can be configured as ILOGICE2 in HP I/O banks, and as ILOGICE3 in HR I/O banks. ILOGICE2 and ILOGICE3 are functionally identical except that ILOGICE3 has a zero hold delay element (ZHOLD) which can be configured with IOBDELAY. Refer to the 7 Series FPGAs SelectIO Resources User Guide (UG471) or the UltraScale Architecture SelectIO Resources User Guide (UG571) for more information on the use of IOBDELAY.
- Architecture Support
- All architectures.
- Applicable Objects
-
- Ports (
get_ports) - Cells, for assignment to input buffers (IBUFs)
- Nets
- Ports (
- Values
-
-
NONE: Sets the delay to OFF for both the IBUF and input flip-flop (IFD) paths. -
IBUF- Sets the delay to OFF for any register inside the I/O component.
- Sets the delay to ON for the buffered path through the ILOGIC block.
-
IFD- Sets the delay to ON for the IFF register inside the I/O component.
- Sets the delay to OFF for the BUFFERED path through the ILOGIC.
-
BOTH: Sets the delay to ON for both the IBUF and IFD paths.
-
Syntax
- Verilog Syntax
-
Place the Verilog constraint immediately before the module or instantiation. Specify the Verilog constraint as follows:
(* IOBDELAY = {NONE|BOTH|IBUF|IFD} *) - VHDL Syntax
-
Declare the VHDL constraint as follows:
attribute iobdelay: string;Specify the VHDL constraint as follows:
attribute iobdelay of {component_name |label_name }: {component|label} is “{NONE|BOTH|IBUF|IFD}”; - XDC Syntax
-
set_property IOBDELAY value [get_cells cell_name]Where
valueis one of NONE, IBUF, IFD, BOTH.XDC Syntax Example:
set_property IOBDELAY "BOTH" [get_nets {data0_I}]
Affected Steps
- Timing
- Place Design
- Routing