本文内容来自：http://www.stm32circle.com/hom/index.php
Description:（说明）
 

BeepTimer is a countdown timer. The user controls it by tilting the whole device and by pushing the button.
The typical usage proceeds as follows:

   

• Start the program.   
  
• Tilt the device to the left or to the right to change the time interval.   
  
• Push button to start the countdown. A short while after the start the screen will go off. The green LED will blink shortly every second the contdown continues.   
  
• You may cancel the countdown pushing the button shortly.   
  
• After the countdown ran through, the device begins to blink intensely with the red LED and to beep (because of a bug in Circle OS it  is possible that there will be no sound). Push the button shortly to stop the signalling and to put the countdown into original state.   
  
• At any point you may exit the program -- press the button and turn the device over at the same time.
  

The program is free for personal use; otherwise, feel free to contact the author through the forum (personal message is sufficient).