在嵌入式系统的开发过程中经常会遇到预期的事件未发生，测控系统将会永远处于等待。这时候超时控制就显得尤为重要。本文介绍了几种超时的算法。-In the development process of embedded systems often encounter the expected event did not occur, monitoring and control system will be a perpetual state of waiting. At this time the timeout control is particularly important. This article describes several timeout algorithm.