stm32 - Interrupt handle

Calling main() in any event is a bad idea, calling it from an interrupt handler is a really bad idea as you have discovered.

What you really need is to modify the stack and link-register so that when the interrupt context exits,, it "returns" to main(), rather than from whence it came. That is a non-trivial task, probably requiring some assembler code or compiler intrinsics.

You have to realise that the hardware will not have been restored to its reset state; you will probably need at least to disable all interrupts to prevent them occurring while the system is re-initialising.

Moreover the standard library will not be reinitialised if you jump to main(); rather than the reset vector. In particular, any currently allocated dynamic memory will instantly leak away and become unusable. In fact all of the C run-time environment initialisation will be skipped - leaving amongst for example static and global data in its last state rather than applying correct initialisation.

In short it is dangerous, error-prone, target specific, and fundamentally poor practice. Most of what you would have to do to make it work is already done in the start-up code that is executed before main() is called, so it would be far simpler to invoke that. The difference between that and forcing a true reset (via the watchdog or AICR) is that the on-chip peripheral state remains untouched (apart from any initialisation explicitly done in the start-up). In my experience, if you are using a more complex peripheral such as USB, safely restarting the system without a true reset is difficult to achieve safely (or at least it is difficult to determine how to do it safely) and hardly worth the effort.