说明：  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。
(article introduces ARM JTAG Debugging the basic principles. The basic content including TAP (TEST PORT ACCESS) and BOUNDARY- SCA N ARCHITECTURE presentation on this basis, ARM7TDMI detail with the principles of JTAG debugging.)