说明：  这篇文章主要介绍ARM JTAG调试的基本原理。基本的内容包括了TAP (TEST ACCESS PORT) 和BOUNDARY-SCAN ARCHITECTURE的介绍，在此基础上，结合ARM7TDMI详细介绍了的JTAG调试原理。
(This article introduces the ARM JTAG debug the basic principles. Basic elements include TAP (TEST ACCESS PORT) and BOUNDARY-SCAN ARCHITECTURE introduction On this basis, the combination of ARM7TDMI detailed principle of the JTAG debugger.)