为了访问Cortex ™ -M3 TAP 对芯片进行调试，必须：
1. First, it is necessary to shift the BYPASS instruction of the boundary scan TAP.
2. Then, for each IR shift, the scan chain contains 9 bits (=5+4) and the unused TAP instruction must be shifted in  using the BYPASS instruction.
3.  For each data shift, the unused TAP, which is in BYPASS mode, adds 1 extra data bit in the data scan chain.

Note: Important : Once Serial-Wire is selected using the dedicated ARM JTAG sequence, the boundary scan TAP is automatically disabled (JTMS forced high)。


以上该如何理解？？？

现在IDCODE可以读到，但是读写有问题。
①for each IR shift, the scan chain contains 9 bits (=5+4) and the unused TAP instruction must be shifted in  using the BYPASS instruction.
该如何实现？

②For each data shift, the unused TAP, which is in BYPASS mode, adds 1 extra data bit in the data scan chain.
adds 1 extra data bit是放在最后移入吗？
该如何实现正确读写？

请教大神指导指导！
是否有Demo可供参考？