请问怎么根据执行函数的持续时间来定义中断的调用

大家好，
我有一个在中断中被调用的函数。我希望根据执行函数的持续时间来定义中断的调用。
正常地知道执行的持续时间，我在开始设置一个PIN，并在函数的末尾清除PIN。我看一个示波器的持续时间。
但是在家里我没有示波器。有没有简单的方法知道持续时间？我有一个UART发送数据
谢谢你



     以下为原文
   Hi everyone,
    I have a function which is called in an interruption. I would like define the call of my interruption according to the duration of execution of my function.
    Normaly to know simply the duration of execution I set a pin at the begining and clear the pin at the end of the function. I look on a oscilloscope the duration.
    But at home I haven't osciloscope. Is there a simply method to know the duration? I have  a UART to send data
     
     
     
    Thank you