Mentor v8.6_4 manual Add Pin Constraints Command Dictionary

Add Pin Constraints Command Dictionary

You can force constrained pins in test procedures to the opposite of the constrained value, provided you put the pin back again to its constrained value by the end of the procedure. The DRC process keeps track of which pins are forced to the opposite of their constrained value in the test procedures.

FlexTest Specifics

The Add Pin Constraints command adds cycle behavior constraints to the specified primary input.

For every primary input for which you do not specify a constraint by using the Add Pin Constraints command, FlexTest automatically uses the default format type NR, with a period of 1, and offset of 0. You can change the default format by using the Setup Pin Constraints command.

You specify the test cycle width by using the Set Test Cycle command.

You can constrain a clock pin to its off-state to prevent its use as a capture clock during the ATPG process. The constrained value must be the same as the clock off-state or an error occurs. All clocks with a 0 off-state should have a return-zero waveform. Likewise, all clocks with a 1 off-state should have a return-one waveform. You cannot constrain an equivalent pin, with the exception of a NR format pins.

FlexTest provides 11 constraint formats from which you choose the constant value that you want to apply to an primary input. Further, these constraint formats (waveform types) group into three waveform classes which apply to all automatic test equipment:

Group 1 Non-return waveform; the pin value may change only once. Includes the NR, C0, C1, CZ, and CX constraint formats. Group 1 waveforms require you to specify the period and offset. If not specified for C0, C1, CX, and CZ, FlexTest assumes the period is 1 and the offset is 0.

Group 2 Return-zero waveform; the pin value may rise to a 1 and then return to a 0. Includes the R0, SR0, and CR0 constraint formats. Group 2 waveforms require you to specify the period, offset, and pulse width.

2-94 FastScan and FlexTest Reference Manual, V8.6_4