Slide 96 of 173
Notes:
There are four major modes for the boundary-scan cell. The normal mode simply passes inputs to outputs. The scan mode passes data from SIN to Qa and from Qa to Sout. Capture mode loads the value on the input to Qa. Finally, update mode loads values from Qa to the output.
To shift in and apply data, the scan mode would be selected until the data is shifted in and then one cycle of update mode would be selected. To capture data and scan it out, one cycle of capture mode would be selected followed by the required number of scan cycles.
