wrt to the bi-dir pads, a mux has to be used to select between the i/p and the o/p ports
the select signal of the mux had to be "TEST ENABLE" signal so that when TEST EN = 1, then the the port as to act as an "input port" and the scan data has to enter the chip !!
i do not have ne material on this, but have worked on BI-DIR ports and scan insertion ... this is what i have done !!
Does not using only the enable signal lead to a loss in test coverage of some combinational logic circuit in the design and that using the test mode signal along with the enable signal improves test coverage?. I am looking for some pictorial representation of IO and bidi pads to understand them better.