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METHOD FOR CONSTITUTING PROGRAMMABLE INTEGRATED CIRCUIT, USAGE OF PROGRAMMABLE INTEGRATED CIRCUIT AND JTAG CIRCUIT, AND USAGE OF COMMAND INPUTTED TO JTAG COMMAND REGISTER
METHOD FOR CONSTITUTING PROGRAMMABLE INTEGRATED CIRCUIT, USAGE OF PROGRAMMABLE INTEGRATED CIRCUIT AND JTAG CIRCUIT, AND USAGE OF COMMAND INPUTTED TO JTAG COMMAND REGISTER
PROBLEM TO BE SOLVED: To provide a technology to give a high system performance by increasing the number of external pins that can be utilized to the input/output of user data and increasing the amount of data that can be transferred in parallel. SOLUTION: The JTAG circuit can test pin connection without using any physical test probe and can obtain functional data while a device is operating normally. A JTAG state machine 210 is a state machine for giving output signals SHFTIR, CLKIR, UPDTIR, SHFTDR, CLKIR, and UPDTDR based on the input of TMS, ITST, and TCLK. The machine 210 controls the operation of a circuit. The TDI is a series input to a command register 220, the TDO is a series output, and the machine 210 controls the series feed of a command from the TDI to a register 220. A control logic 230 generates a signal 235, which is sent to a proper JTAG circuit for controlling operation. The logic 230 generates a signal 240 that is fed to a mode coder 250, receives input from mode selection pins 1 and 2, and generates a mode signal 255.
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