Table Of Contents

Keep Alive Patterns

Last Modified: November 23, 2020

Keep alive patterns are specialized, simple looping patterns designed to keep the DUT from unlocking clocks and PLLs while you perform other tasks, such as loading or unloading patterns, changing time sets, changing digital pattern instrument configurations, or moving from one test to another in the test program.

Select File»New or click the Add Item button Add Item on the Project Explorer window toolbar to create a new document. Double-click a .digipat file in the Project Explorer window or right-click the file and select Open from the context menu to launch the pattern document. The toolbar for a keep alive pattern includes only buttons relevant to keep alive patterns. The keep alive pattern document includes a status indicator and a Keep Alive Pattern indicator.

To burst a keep alive pattern, first load the keep alive pattern and then burst a standard pattern that jumps to a keep alive pattern.

You must also use the keep_alive opcode to switch to a keep alive pattern from a standard pattern. You must use the keep_alive opcode on the last vector of a keep alive pattern to loop the keep alive pattern until you burst another pattern or until you abort the keep alive pattern. You can load or unload only one keep alive pattern on or from the digital pattern instrument at a time.

History RAM results for the standard pattern that jumped to the keep alive pattern do not change while the keep alive pattern executes.

If the keep alive pattern does not use all the pins referenced in the standard pattern that was executing before you called the keep alive pattern, the pins excluded from the keep alive pattern maintain their previous state.

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