21.8.37 remove_clock_uncertainty
(Ask a Question)Description
Removes a clock-to-clock uncertainty from the current timing scenario by specifying either its exact arguments or its ID.
If the specified arguments do not match clocks with an uncertainty constraint in the current scenario, or if the specified ID does not refer to a clock-to-clock uncertainty constraint, this command fails. Do not specify both the exact arguments and the ID.
remove_clock_uncertainty -from | -rise_from | -fall_from from_clock_list -to | -rise_to | \
-fall_to to_clock_list -setup {value} -hold {value} | -id constraint_ID Arguments
| Parameter | Type | Description |
|---|---|---|
from | list of strings | Specifies that the clock-to-clock uncertainty applies to both rising and falling edges of the source clock list. Only one of the -from, -rise_from, or -fall_from arguments can be specified for the constraint to be valid. |
rise_from | list of strings | Specifies that the clock-to-clock uncertainty applies only to rising edges of the source clock list. Only one of the -from, -rise_from, or -fall_from arguments can be specified for the constraint to be valid. |
fall_from | list of strings | Specifies that the clock-to-clock uncertainty applies only to falling edges of the source clock list. Only one of the -from, -rise_from, or -fall_from arguments can be specified for the constraint to be valid. |
from_clock_list | list of strings | Specifies the list of clock names as the uncertainty source. |
to | list of strings | Specifies that the clock-to-clock uncertainty applies to both rising and falling edges of the destination clock list. Only one of the -to, -rise_to, or -fall_to arguments can be specified for the constraint to be valid. |
rise_to | list of strings | Specifies that the clock-to-clock uncertainty applies only to rising edges of the destination clock list. Only one of the -to, -rise_to, or -fall_to arguments can be specified for the constraint to be valid. |
fall_to | list of strings | Specifies that the clock-to-clock uncertainty applies only to falling edges of the destination clock list. Only one of the -to, -rise_to, or -fall_to arguments can be specified for the constraint to be valid. |
to_clock_list | list of strings | Specifies the list of clock names as the uncertainty destination. |
setup | None | Specifies that the uncertainty applies only to setup checks. If none or both -setup and -hold are present, the uncertainty applies to both setup and hold checks. |
hold | None | Specifies that the uncertainty applies only to hold checks. If none or both -setup and -hold are present, the uncertainty applies to both setup and hold checks. |
id | integer | Specifies the ID of the clock constraint to remove the clock source uncertainty from the current scenario. You must specify either the exact parameters to set the constraint or its constraint ID. |
Error Codes
| Error Code | Description |
|---|---|
| None | Only one argument is needed. |
Supported Families
| PolarFire® |
| PolarFire SoC |
| SmartFusion® 2 |
| IGLOO® 2 |
| RTG4™ |
Example
The following example removes uncertainties from Clk1 clock to Clk2 clock domains.
remove_clock_uncertainty -from [ get-clock {Clk1} ] -to [ get_clock {Clk2} ]The following example removes uncertainties between Clk1, Clk2, Clk3, and Clk4 clock domains with specific edges.
remove_clock_uncertainty -from [ get_clocks {Clk1} ] -fall_to [ get_clocks {Clk2 Clk3} ] -setupremove_clock_uncertainty 4.3 -fall_from [ get_clocks {Clk1 Clk2} ] -rise_to [ get_clocks {*} ]remove_clock_uncertainty 0.1 -rise_from [ get_clocks {Clk1 Clk2} ] \
-fall_to [ get_clocks {Clk3 Clk4} ] -setupremove_clock_uncertainty 5 -rise_from [ get_clocks {Clk1} ] -to [ get_clocks {*} ]remove_clock_uncertainty -id $clockId