An alcohol detector based on MCU ADuC842 was designed. The working principle and design method of the de⁃tector are introduced. The alcohol information in expiration is sampled by gas sensor MQ⁃3,and its digital signal is converted and processed by microcontroller ADuC842. The detected alcohol concentration is displayed by LCD1602 in real time,and com⁃pared with the setting thresholds to determine the alarm levels. The experiment result shows that the testing range of alcohol con⁃centration is 0~0.72 mg/L and the error is less than 0.03 mg/L. The system is simple and easy to use,which can be used to de⁃tect the alcohol concentration of drivers.%设计一款基于单片机ADuC842的酒精测试仪，并介绍该系统的工作原理和设计方法。呼气中的酒精信息由气敏传感器MQ⁃3采集，送到单片机ADuC842进行A/D转换和处理，将检测的酒精浓度通过LCD1602实时显示，另一方面与预设的酒精浓度阈值范围比较并给出报警等级。实验样机测试表明，该系统结构简单，操作方便，呼气酒精浓度测量范围为0~0.72 mg/L，误差不超过0.03 mg/L，可用于驾驶员酒精浓度的自我检测和监控。
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