Thus there are 16 multiplexers connected to the NVIC and are named as External Interrupt/Event Controllers, EXTI0, EXTI1, etc. There are 16 external interrupt lines with separate interrupt vector addresses that are connected with GPIO pins. We will learn about them when we learn about the related hardware with them. We won’t also look into them in this post. There are other interrupts that are related to RTC, timer, etc. As per STM32’s reference manuals for more information on exceptions and NVIC programming read Chapter 5 Exceptions and Chapter 8 Nested Vectored Interrupt Controller of the ARM Cortex-M3 Technical Reference Manual. In some upcoming post may be I’ll discuss the NVIC in details. However at present I’m not going to go that deep as that’s not needed for now. In many MCUs’ interrupt system, interrupt priority can be set and Reset has the highest interrupt priority over anything else. Our job is simply to enjoy the lightning fast interrupt responses owing to the NVIC. There are several features of the NVIC and these are handled by the compiler. It ensures low latency and high performance. The Cortex M3 based MCUs have a sophisticated and yet easy to use interrupt system called the Nested Vectored Interrupt Controller ( NVIC). STM32F1xx series are ARM Cortex M3 based MCUs. To get rid of these issues, we’ll need to use external interrupts – a vital feature in every common microcontroller. Thus the overall performance is poor and not real-time.

This is simply so because the CPU will have to check the GPIO’s logic state every time the super-loop (while (1) loop in the main function) repeats and the push button will also not be responsive during the software delay function calls. Obviously that won’t be an efficient technique when a program will be of a considerable size and complexity. That example was based on polling method where the code continuously monitored the logic state of a GPIO input pin attached to a push button to determine the delay amount. In my earlier post on STM32 GPIOs I showed how to flash a LED with variable delay times.

Stm32f4 hal disable interrupt gpio