Apparatus and method for performing boundary scans using fixed and variable signal groups

摘要

In a JTAG test and debug environment, the signal groups may have a variable length, a fixed length or a combination of both fixed and variable signal groups to be transferred to the target processor. To implement the three types of data transfers, the storage unit associated with the scan control unit includes two types of storage locations, fixed signal length storage locations and variable length storage locations. The software can select the mode of data transfer and this selection is provided to the scan controller by a command.