I have unique requirement that scan mode be set by internal register which would control output at PO. By default PI/PO which drives scan are set for something else. Before scan starts, I need to set register to a proper value so PI and PO controls inserted scan chain. I do know that there exist a way to have tester drive the Register interface to drive PI to set registers to desired value. What I do not now how to generate such pattern that tester understands and how to include them in initialization sequence.
First, I am assuming that those control registers are not part of any of your normal ATPG chains, correct? Also, from your description are you just setting internal values to change your PO's to proper outputs for your SO's? Anything else this configuration does?
Any type of setup sequence like this would be included in your modeinit sequence. Do you currently have a custom modeinit sequence? If not, then one needs to be created. let me know where you are at with this so I can help you further.