Test wrapper design for IP-core test reuse

An improved wrapper cell was presented based on analysis of two kinds of wrapper cells. It adds a mux to the traditional P1500 wrapper cell, which can test the data path of wrapper cells and also resolve the problem of safe shifting of scan chains during shifting;and reduces the dynamic test power during scan shifting. A kind of wrapper, namely tri-state wrapper, was put forward based on analysis of two kinds of wrappers: IEEE P1500 wrapper and TestShell from Philip. The architecture allows different cores to be connected directly to the same test bus.