Working with Constraints

About User Constraints

User constraints are entered in the “User Constraint Panel” and represent actual part constraint specified by the manufacturer. A “User Constraint” needs to specified before adding a constraint in the diagram.

Adding New Constraints

1. Select 2 edges. The first edge selected should occur in time before the second.
2. Add Menu -> Constraint or Ctrl 8 or pop-up menu -> Add Constraint
3. Enter user constraint parameters in the “User Constraint Panel” if this is the first time defining this constraint. If the user constraint has already been defined, skip this step.
4. Enter the constraint parameters in the “Constraint Panel” and hit the “Add” button.

Time Calculations

Constraints are used to specified parameters like setup and hold times and pulse width min and max times. When specifying a constraint, the constraint type allows you specify how the time is calculated between two edges.

• Max-Min – measured from source edge max time to the destination edge min time.
• Max-Max – measured from source edge max time to the destination edge max time.
• Min-Max – measured from source edge min time to the destination edge max time.
• Min-Min – measured from source edge min time to the destination edge min time.

Adding Previously Used Constraints

1. Select 2 edges. The first edge selected should occur in time before the second.
2. Pop-up menu, select “Add Used Constraint”

Selecting and Deselecting

select

1. Drag the mouse so the select rectangle contains the constraints
2. Hold down the Shft key and click on the constraint names

deselect

1. Click in empty area in timing diagram. This deselects all objects.
2. Hold down the Shft key and click on the constraint names

Moving

1. Select the constraints.
2. Use Alt and left key to move the constraints back one half clock cycle
3. Use Alt and right key to move the constraints forward one half clock cycle.

Moving the Text Labels

horizontally

1. Select the constraints.
2. Use left or right key to move the label to the left, right, or center position.

vertically

1. Select the constraints.
2. Use up and down keys to move the label. Use the Shft or Alt key with the up and down key to precisely position the text. You can select multiple constraints and move all the labels at the same time.

Deleting

1. Select the constraints.
2. Use the delete key.