| 摘要 |
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. |
