一、arm debug调试头
1.1、硬件版本小结
arm debug头版本之间的区别：
- V4开始支持swd
- V5开始支持swo
1.2、实物图
3、拆机图
V2:
This one consists of a 24C02 serial flash and a ALVC164245 level translating tri-state buffer.
V3:
This one looks like the current debug adapter cables, except with a 20pin IDC socket rather than pigtail. even though it is for an older core design than the LA-7742.
Inside it appears more complicated, and seems be the same 24C02 serial flash, but instead has MAX4615/6 analog switches, DS90C032 quad differential receivers, and some PACDN006 ESD diode packs.
ref：
https://repo.lauterbach.com/pdfnew/app_arm_target_interface.pdf
https://www2.lauterbach.com/pdf/c166_app_ocds.pdf
https://repo.lauterbach.com/differences_between_standard_and_automotive_debug_cables.pdf