How do I get code execution time in MicroSecond while running timer interrupt on Stm32?

How do I check the operating time of the code in MicroSecond units during timer interrupt execution?

I would like to know how to get the execution time of code on STM32 IDE.
Thank you.

To measure microseconds, you need some hardware timer. The easiest to implement would be the SysTick timer, which is built into the core itself, and is extremely simple to configure. All you need to do is to set the counter reload value, counter current value, and clock source. Clock source can be the CPU clock, which means, you can literally count the number of cycles it takes for anything.

Save counter value into (global, if you wish) variable, run function, save new counter value into variable two. The difference between the two is roughly the number of clock cycles it took, with pretty good precision.

The timer itself is precise, it's a little overhead to read/save the counter variable, but if you do that without interrupt straight by reading from the counter, then all of that will take under 10 clock cycles, which is likely tolerable error.

Obviously, if you know CPU frequency and how many clock cycles it took for something to run, you basically have the time.

SysTick configuration of STM32 is covered in Programming Manual document for your MCU (or, rather, its core). It's an extremely simple peripheral consisting of only 4 registers, with literally only a pair of things that need to be configured there.

1. No need to activate its clock in RCC, it always has clock.
2. Set counter value to start value (it counts DOWN). Could be 0xFFFFFF (it's a 24-bit down counter)
3. Set reload value to counter value (typically; so when counter reaches 0, it will start from the same counter value again).
4. Set SysTick clock source to CPU clock rather than external clock signal
5. When you actually need it, enable counter.
6. Stop the counter when you're done measuring.
7. Read the counter value again. The difference between counter values is the number of clock cycles passed.

Obviously, if your function takes more than full countdown, it won't work, so you'll have to implement a systick interrupt then to have a variable which will contain how many countdowns have passed. This will add an overhead of ~30 cycles per interrupt (interrupt entry, interrupt exit, counter increment). So at the end you will have a number of full countdowns passed plus the remainder counter value.

If you need SysTick for other purposes, you can totally do this with any other hardware timer, just bear in mind their source clock frequency is typically related to APBx or AHB frequency (depending on timer and its clock source configuration, which could be inside the timer itself or RCC dedicated clock configuration registers, if they're present)