Ivthandleinterrupt 【Must See】

NVIC->ICPR[0] = (1 << irq_num); // clear pending

This function was the traffic cop. It took the interrupt number—the vector —and decided which driver function to call. It was beautiful in its simplicity, a massive switch statement that held the system together. ivthandleinterrupt

But a more robust ivthandleinterrupt would query the hardware: NVIC-&gt;ICPR[0] = (1 &lt;&lt; irq_num); // clear pending

This is incredibly useful to see: