> Can the STM32 internally reset itself without using the reset function?
I don't know what exactly do you mean by "reset function" but the mcu can be reset by pulling down its NRST pin, through the brownout detector when the supply power falls below its set minimum (which may be consequence of some faulty hardware or even faulty software e.g. causing unexpectedly high current e.g. by settingerrorneously an input pin as output, setting it against an external source), setting SYSRESETREQ bit in the processors' AIRCR register (so called software reset), letting the watchdogs expire, and maybe some other reasons.
Read the Reset subchapter of the RCC chapter in the reference manual for all the details.
JW
