如何在STM32上获得时间间隔? [英] How to get time intervals on STM32?

问题描述

我想测量单个函数在 STM32 上需要多长时间.我唯一能找到的是SysTick_Handler.但是，这是一个周期性中断，但我需要的是获取时间间隔，如:

I want to measure how long does a single function take on STM32. The only thing I could find is SysTick_Handler. However, that is an periodic interrupt, but what I need is get time interval like:

long t1 = mcu_clock();
sleep(20);
long t2 = mcu_clock();
long diff = (t2 - t1);

我尝试过 C clock()，但它不起作用并且总是返回 -1.我该怎么做?

I've tried C clock(), but it didn't work and always return -1. How can I make it?

推荐答案

首先，在启动时启用一次循环计数器:

First, enable the cycle counter once at startup:

CoreDebug->DEMCR |= CoreDebug_DEMCR_TRCENA_Msk;
DWT->CYCCNT = 0;
DWT->CTRL |= DWT_CTRL_CYCCNTENA_Msk;

然后，您可以访问其值:

then, you can access its value:

unsigned long t1 = DWT->CYCCNT;
/* do something */
unsigned long t2 = DWT->CYCCNT;
unsigned long diff = t2 - t1;

它计算经过的 cpu 周期，您必须将其除以 cpu 时钟频率才能获得以秒为单位的值.

It counts the elapsed cpu cycles, you have to divide it with the cpu clock frequency to get a value in seconds.

因为它是一个 32 位值，所以它可以在更高的时钟频率下非常快地溢出，例如在 216 MHz 时为 19.88 秒.

As it's a 32 bit value, it can overflow quite fast at higher clock frequencies, e.g in 19.88 seconds at 216 MHz.

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