ISR

printf in ISR, missing volatile, heavy processing, forgotten flag clear — we deliberately trigger every classic embedded landmine and watch them fail. Applies to Arduino, ESP32, Renesas, PIC — every MCU with interrupts.

Why does polling fail when you need to ‘do something every 1ms’? Understand the vector table, NVIC, and context saving — then implement a 1ms periodic event with TIM2 interrupts.