6.2.2.6 Software reset (SW)
The SYSRESETREQ field in the NVIC application interrupt and reset control register
can be set to force a software reset on the device. (See ARM's NVIC documentation for
the full description of the register fields, especially the VECTKEY field requirements.)
Setting SYSRESETREQ generates a software reset request. This reset forces a system
reset of all major components except for the debug module.
这里说用NVIC这个标志位就可以复位。