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This section describes the dialog boxes that are used to create and modify constraints.
The Clock Period dialog box enables you to create a global clock period constraint.
Figure 5.5 Clock Period Dialog Box| Field | Description |
|---|---|
| TIMESPEC Name | A text box used to enter the name of the time spec for the period. The name should be entered in the form TSid, where id is a unique name. The name can consist of letters, numbers, or the underscore character (_). |
| Clock Net Name | By default, this field is filled in with the name of the clock you selected on the Global tab grid. |
| Specific Time | A button used to indicate that the specified clock period is to be explicitly defined by the user; that is, not relatively defined by another time spec. |
| Time | A text box used to enter a value which represents the duration of the clock period. |
| Units | A pull-down list used to select a unit of time. The default is %, which is the percentage of the period that the clock is high or low. |
| Start High/Start Low | Buttons used to specify that the initial pulse for the clock period is to be in a high or low state. |
| Time HIGH/LOW | A text used to enter the duration of the high (or low) state for the clock period. |
| Units | A pull-down list used to select a unit of time. |
| Relative to other PERIODTIMESPEC | A button used to specify that the clock period is to be relative to another clock period specification. |
| Reference TIMESPEC | A pull-down list used to select the name of the time spec relative to the clock period. |
| Multiply by/Divide by Factor | Buttons and a text box used to specify the factor of multiplication or division to be applied to the relative clock period. |
The Pad to Setup dialog box allows you to enter a Pad to Setup constraint.
Note: The appearance of the Pad to Setup dialog box varies slightly depending on which tab window you use to open the box.
Figure 5.6 Pad to Setup Dialog Box (Opened from the Advanced Tab Window)| Field | Description |
|---|---|
| Pad Net | This field appears only if you opened the Pad to Setup dialog box from the Ports tab window. Select this if your constraint applies only to a specific pad net, then select the name of the pad net from the pull-down list. |
| Pad Group | This field appears only if you opened the Pad to Setup dialog box from the Advanced tab window. Select this if your constraint applies to a group of pads, then select the name of the group from the pull-down list. |
| Time Requirement | A text box used to enter the amount of time that data must arrive at the edge of a device before the next clock arrives at the edge of the device. |
| Units | A pull-down list used to select a unit of time. |
| Relative to Clock Pad Net | The clock net driving the synchronous elements. This must be correctly selected to prevent invalid constraints. |
| Register Timegroup | A user-defined register timegroup. This field applies only if you opened the Pad to Setup dialog box from the Advanced tab window. |
The Clock to Pad dialog box allows you to enter a Clock to Pad constraint.
Note: The appearance of the Clock to Pad dialog box varies slightly depending upon which tab window you use to open the box.
Figure 5.7 Clock to Pad Dialog Box (Opened from the Ports Tab Window)| Field | Description |
|---|---|
| Pad Net | This field personally if you opened the Clock to Pad dialog box from the Ports tab window. Select this if your constraint applies only to a specific pad net, then select the name of the pad net from the pull-down list. |
| Pad Group | This field appears only if you opened the Clock to Pad dialog box from the Advanced tab window. Select this if your constraint applies to a group of pads, then select the pad group name from the pull-down list. |
| Time Requirement | A text box used to specify the amount of time that data must leave the edge of a device after the current clock edge arrives at the edge of the device. |
| Units | A pull-down list used to select a unit of time. |
| Relative to Clock Pad Net | A pull-down list used to specify the clock net driving the synchronous elements. This must be correctly selected to prevent invalid constraints. |
| Register TimeGroup | A pull-down list used to specify a user-defined register timegroup. This field applies only if you opened the Clock to Pad dialog box from the Advanced tab window. |
The Pad to Pad dialog box allows you to specify a maximum time for the data to enter the chip, travel through combinatorial logic and routing, and leave the chip.
Figure 5.8 Pad to Pad Dialog Box| Field | Description |
|---|---|
| Time Spec Name | A text box used to display the default name of the time spec (TS_P2P). You may change the name if you like, but all timing specification names must begin with the characters TS. |
| Time | A text box used to enter a pad to pad maximum delay value. |
| Units | A pull-down list used to select a unit of time. |
This dialog box allows you to lock a user-defined port to a device pin.
Figure 5.9 Location Dialog Box| Field | Description |
|---|---|
| Location | A text box used to enter the pin name of the port you wish to lock. |
This dialog box allows you to prohibit the use of an I/O site by PAR and FPGA Editor.
Figure 5.10 Prohibit I/O Locations Dialog Box| Field | Description |
|---|---|
| I/O Location | A text box used to enter the pin name of the location you wish to disallow. |
| Add Configuration Pins | A button used to place the names of configuration pins for a device into the Prohibit I/O Locations box. Configuration pins are used to load design-specific programming data into one or more logic blocks to define the functional operation of a device's internal blocks and interconnections. |
| Prohibit I/O Locations | A list box used to display prohibited locations. |
This dialog box enables you to create a new time name based on either of group of elements by nets or by instance name. A time name (TNM) is an attribute that can be used to identify the elements that make up a group, which can then be used in a timing specification.
Figure 5.11 Time Name Dialog BoxThe functions of the dialog box are described below.
| Field | Description |
|---|---|
| Time Name | A text box used to enter a name for the new group. |
| Design Element Type | A pull-down list used to display either a list of nets or a list of elements, depending on which button you used on the tab window to open the box. If you are creating a group of elements associated by nets, the list includes Clock Nets, All Nets, or Clock Enable Nets. If you are creating a group of elements by instance name, the list shows FFs, Pads, Input Pads, Output Pads, Bi-directional Pads, Tri-stated Pads, RAMs, and Latches. |
| Filter | A text box used to limit the list of available elements. Entries may consist of any string. For example, if you wanted to list only nets containing the string "test," you would type test in the Filter box. Names are not case-sensitive. |
| Available | A box used to display either the net names under the net group you selected or the instance names of the element you selected from the Design Element Type pull-down list. |
| Time Name Targets | A list used to identify elements selected from the Available window. The names on this list constitute the new time group. |
This dialog box enables you to create a new group according to the element output net name.
Figure 5.12 Time Group Dialog BoxThe functions of the dialog box are described below.
| Field | Description |
|---|---|
| Time Group Name | A text box used to enter the name of the new time group. |
| Design Element Type | A Pull-down list used to display names of design element types. The list includes FFs, All Pads, Input Pads, Output Pads, Bi-directional Pads, Tri-stated Output Pads, RAMs, Latches, and User Groups. |
| Filter | A text box used to limit the list of available elements. An entry in this box may consist of any string. For example, if you wanted to list only pad names containing the string "CE_TEST," you would type ce_test in the Filter box. Names are not case-sensitive. |
| Name Available | A box used to display all of the instance names of the available design element type selected from the Design Element Type pull-down list. Name is the selected element type. |
| Time Group Members | A list used to identify elements selected from the Name Available window. The names displayed on this list constitute the new time group. |
The Timing THRU Point (TPTHRU) dialog box allows you to specify an intermediate point in a path.
Figure 5.13 Timing THRU Point Dialog Box| Field | Description |
|---|---|
| TPTHRU Name | A text box used to enter a unique name for the constraint. |
| Design Element Type | A pull-down list used to show the design element types. Choose between All Nets and TBUFs. |
| Filter | A text box used to limit the list of available elements. Entries may consist of any string. For example, if you wanted to list only nets containing the string "clk," you would type clk in the Filter box. Names are not case-sensitive. |
| Available | A list box showing the available nets or instances, depending upon your selection from the Design Element Source pull-down list. |
| TPTHRU Targets | A box showing the timing point(s) in the path that you have specified. If you selected more than one timing point, they will be treated as a group. |
The FROM/THRU/TO dialog box allows you to stipulate a maximum allowable time delay between groups of elements through specified intermediate points and to specify paths that will be ignored by timing.
Figure 5.14 FROM/THRU/TO Dialog Box| Field | Description |
|---|---|
| Time Spec Name | A text box for used to enter the name of the time spec in the form TSid, where id is a unique name. The name can consist of letters, numbers, or the underscore character (_), but it must begin with the letters TS. |
| From Group | A pull-down list used to select the source group to which the constraint applies. |
| To Group | A pull-down list used to select the destination group to which the constraint applies. |
| THRU Points (Optional) | A list box used to show the intermediate points that have been defined with the Constraints Editor Timing THRU Point dialog box |
| Explicit | A button used to indicate that the time spec is explicit; that is, non-relative to any other time spec. This is the default configuration for the Slow/Fast Path Exceptions constraint. |
| Time | A text box used to enter the maximum allowable delay between the source group and the destination group. |
| Units | A pull-down list used to enter a unit of time. |
| Relative to other path specification | A button used to identify the new time spec as one that is relative to another time spec. This is the default configuration for the Multicycle Paths constraint. |
| Reference TIMESPEC | The name of the time spec referenced if you identified the time spec name as relative. |
| Multiply by/Divide by | Buttons used to select the mathematical operation between the new time spec and the relative time spec. |
| Factor | A text box used to enter a value for the multiplication or division factor. |
| Mark as false paths | A button used to specify that the selected groups and timing points will be ignored by timing. This is the default configuration for False Paths (FROM TO TIG). |
The Timing Ignore dialog box allows you select timing specifications that contain a net that you want timing to ignore.
Figure 5.15 Timing Ignore Dialog Box| Field | Description |
|---|---|
| Net | A pull-down list used to select the name of the net that you wish to be ignored by timing. |
| TIMESPECs Available | A list box used to show the available time specifications containing the selected net. If you do not select any time specs, the constraint will apply to all of the time specs displayed in this list. |
| Ignored TIMESPECs | A list box used to display the specs selected from the TIMESPECs Available list. |
The Voltage dialog box allows you to specify a non worst case operating voltage. This provides a means of prorating delay characteristics based on the voltage you specify.
The prorating voltage range differs by family.
Figure 5.16 Voltage Dialog BoxThe text box is for entering a value for voltage. The value may be an integer or whole number and varies for different devices.
The Temperature dialog box allows you to specify a non worst case operating temperature, which provides a means of prorating device delay characteristics based on the specified junction temperature.
Each architecture has its own specific range of valid operating temperatures.
Figure 5.17 Temperature Dialog Box