Timing

Use the timing document to view, create, modify, save, and apply timing files (.digitiming). Timing files include period, edge multiplier (edge x), drive format, and edge information for pattern execution. Timing files currently can contain only one timing sheet, which is a collection of time sets. An asterisk (*) next to a filename in the Project Explorer window and in the document tab indicates that the file has been modified but not saved.

Select File»New or click the Add Item button on the Project Explorer window toolbar to create a new document. Double-click a .digitiming file in the Project Explorer window or right-click the file and select Open from the context menu to launch the timing document.

The timing document displays configuration components of the time sets, including the format and edge placement that shape the digital waveform on a per-pin basis. You can define multiple time sets with different edge multiplier, format, and edge placement components per pin to use on different vectors in the pattern. Each vector references only one time set. You can create as many time sets as you have unique combinations of pin behavior required in pattern burst up to the maximum number of uniquely named time sets the digital pattern instrument supports. Refer to the specifications document for the digital pattern instrument for more information about the number of supported time sets. You can create multiple timing files and apply those values to separate pattern bursts.

A time set can include timing definitions for multiple different pins or pin groups, each represented on a separate row in the timing document. You can define the same time set more than once for the same pin on different rows if needed. Time set components defined in pin or pin group rows farther down in the list override components defined in pins or pin groups earlier in the list. Use the reorder arrows to drag and drop time set rows to change the order of the time set definitions.

Applying Time Sets

Click the Apply Time Sets button or right-click the timing file (.digitiming) in the Project Explorer window and select Apply Time Sets from the context menu to delete any previously applied values and load all the time set values in the document on the instrument after you make changes. Applying time set values affects all sites, even disabled sites. The Digital Pattern Editor does not prompt you to reapply time set values when you enable a previously disabled site because the time set values have already been applied. The editor validates that all formulas resolve successfully and displays an error message and highlights the related cell for formulas that include errors. The editor prompts you to apply the values in the active timing file when no timing values have previously been applied to the instrument or when previously applied timing values change directly in the timing document or indirectly through changes in the specifications document.

Configuring Time Sets

You can enter and edit numeric values or formulas for the time set components. Formulas can include references to variables defined in specifications files included in the project. By default, the timing document displays the formula definition. Click the Show Formulas/Show Computed Values button to toggle the formula or numeric value view. Hover over the cell to display a tooltip with the formula and resolved value. The document highlights unresolved values and related dependencies and displays a tooltip with error information. Timing files automatically update with the value changes you make in specifications files.

Double-click or start entering data in the empty row at the bottom of the timing table to create a new time set and specify the appropriate values.

You can delete rows by selecting cells in the rows and selecting Delete Selected Row(s) from the context menu or by selecting an entire row by clicking on the row header or selecting every cell in the row and using the <Delete> key.

You can set values for the following components for time sets. You must specify a value for each component. The timing document highlights unspecified components in orange.

• Name — Specifies the name of the time set.
• Period — Specifies the period of vectors that use the time set. You can specify only one period per time set, meaning all pins in the time set use the same period. When you modify the period of a time set, all the rows for that time set automatically update to use the same period.
  

  Note  

  You can specify edges that exceed the period of the time set up to the limits the digital pattern instrument supports, but all edges must still occur in order and must honor all minimum separation requirements. Do not schedule edges for future cycles before all edges of the current cycle complete. Validation for these situations does not occur.

• Pin Item — Specifies a pin or pin group defined in the pin and channel map.
  

  Note  

  Currently, the Digital Pattern Editor does not support using system pins in patterns. To burst from a pin that spans all sites, configure a pin with a shared pin connection in the Pin Map Editor to share a channel across multiple sites and use that pin in your pattern instead.

• Edge Multiplier — Specifies the edge multiplier for a time set. You can choose 1x or 2x multipliers. If you choose 2x multiplier, you can specify values for the 2x edge components, including Drive Data2, Drive Return2, and Compare Strobe2. If the document does not contain any 2x time sets, the 2x edge columns are hidden. The document disables editing 2x edge cells for 1x time set rows.
• Drive Format — Specifies one of the following drive formats, as illustrated in the following figures.
  

  Figure 1. Drive Formats, Including Surround by Complement
  

  Figure 2. Drive Formats, 2x Multiplier
  • NR — Non-return. Setting Drive Format to NR disables the Drive Return cell in that row and clears that cell if a value was present.
  • RL — Return to low.
  • RH — Return to high.
  • SBC — Surround by complement.
• Use the Drive On, Drive Data, Drive Return, Drive Data2, Drive Return2, Drive Off, Compare Strobe, and Compare Strobe2 columns to configure edge components for each pin or pin group per time set.
  

  Note  

  On power-up, pins are in a high impedance state. To avoid unexpected results for DUTs that are sensitive to the initial state of a pattern burst, programmatically specify the initial pin state by using the niDigital Write Static VI, the DigitalPinSet.WriteStatic .NET method, or the niDigital_WriteStatic C function. You can interactively set the initial state for a pin by selecting the corresponding driver symbol in the Drive section of the Pin View pane of the Digital Pattern Editor. After each pattern burst, the ending state of the last executed vector persists until the start of the next pattern burst or until you programmatically or interactively change the pin state or pin function.

  • Drive On — Specifies the delay from the beginning of the vector period for turning on the pin driver. This option applies only when the previous vector left the pin in a non-drive pin state (L, H, X, V, M, E).
  • Drive Data — Specifies the delay from the beginning of the vector period until the pattern data is driven to the pattern value.
  • Drive Return — Specifies the delay from the beginning of the vector period until the pin changes from the pattern data to the return value, as specified by the format. Because not all formats use this column, the document disables editing this field when the drive format does not support it.
  • Drive Data2 — Specifies the delay from the beginning of the vector period until the 2x time set's second pattern data is driven to the pattern value. The document disables editing this column for 1x time sets. The document hides this column if there are no 2x time sets.
  • Drive Return2 — Specifies the delay from the beginning of the vector period until the pin changes from the 2x time set's second pattern data to the return value as specified by the format. Because not all formats use the Drive Return2 column, the document disables editing this field when the drive format does not support it. The document also disables editing this column for 1x time sets. The document hides this column if there are no 2x time sets.
  • Drive Off — Specifies the delay from the beginning of the vector period to turn off the pin driver when the next vector period uses a non-drive symbol (L, H, X, V, M, E).
  • Compare Strobe — Specifies the time when the comparison happens within a vector period.
  • Compare Strobe2 — Specifies the time when a 2x time set's second comparison happens within a vector period. The document disables editing this column for 1x time sets. The document hides this column if there are no 2x time sets.
• Comment — Specifies a text description for the time set row. This field does not accept the <Enter> or <Tab> keys.

Keyboard Shortcuts within the Timing Document

Action	Shortcut
Apply time sets	<Ctrl+L>