Safety: You can't "smoke" a virtual STM32 by accidentally shorting a pin.

#include "main.h"

while (1)

To simulate an STM32 project in SimulIDE, follow these standard steps:

Running an STM32 at 72 MHz in software is impossible. SimulIDE runs roughly at 1–10% of real-time speed, depending on your CPU. Workaround: Reduce clock frequency in firmware (use 8 MHz HSI). Keep loops simple.