PIN FOR MULTIPLEXED CONTROL FOR STATE MACHINE FOR PROGRAMMING AT INSIDE OF SYSTEM WITH BUILT-IN HIGH-DENSITY PROGRAMMABLE LOGIC DEVICE AND FOR BOUNDARY SCANNING

摘要

PURPOSE: To execute both of programming within a system and a boundary scanning test by means of minimum number of pins in a logic IC programmable within the system. CONSTITUTION: The pins are multiplexed so that the connection of SDI, SCLK, MODE and SDO necessary for programming within the system and the connection of TDI, TCK, TMS and TDO necessary for the boundary scanning test can be provided by four common pins. A pin programmable within the system is used for controlling the multiplexing of these pins. In an alternative execution example, both of the programming within the system and the boundary scanning test are executed by the same pin and the same state machine. A test logic architecture regulated by an IEEE technical standard 1149. 1-1990 is utilized. In order to implement the programming within the system, the instruction register of the technical standard 1149. 1-1990 is modified to include a special instruction executing a desired program function.