文章介绍了边界扫描测试的原理 ,分析了联合测试行动组JTAG控制器的逻辑状态 ,并给出了JTAG测试具体应用的VHDL原代码和逻辑仿真波形。利用JTAG接口可以方便地进行复杂IC芯片连接的故障定位 ,灵活控制IC芯片进入特定的功能模式等。 This paper introduces the principle of boundary scan test, analyzes the logic state of the JTAG controller in the joint test operation group, and gives the VHDL original code and logic simulation waveform of the JTAG test. Using JTAG interface can easily complex IC chip connection fault location, flexible control IC chip into a specific functional mode.