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AR# 10763

3.x FPGA Compiler II - Error: Can't find clock - "clk_in" (for set_input_delay and set_output_delay).

Description

Keywords: timing constraints, set_clock, set_input_delay, set_output_delay, CLKDLL, SDC2

Urgency: Standard

General Description:
Within the Synopsys tools, the constraints set_clock, set_input_delay and
set_output_delay will carry forward into the Xilinx implementation tools through
the NCF.

However, when instantiating a CLKDLL in the code, the FPGA Compiler II generates
the following error:

Can't find clock - "clk_in" ' (for set_input_delay and set_output_delay).

Solution

The workaround is to pass the timing constraints through the UCF, using either a
text editor or the Constraints Editor in the Design Manager.

In our tool:

"Set_clock property" is known as "Period."
"Set_input_delay" property is known as "Offset in."
"Set_output_delay" property is known as "Offset out."

NOTE: The problem and workaround will be the same for FPGA Express.
AR# 10763
Date Created 01/11/2001
Last Updated 04/20/2007
Status Archive
Type General Article