：实时采集当前环境温度值，并显示于数码管上。同时，当温度高于某一值时（此处设为31摄氏度），蜂鸣器便会发出报警。而当低于该值时，蜂鸣器自动停止报警。试验时，可用手触摸DS18B20，使其温度升高到31度，观察现象。-: Real-time acquisition value of the current ambient temperature, and displayed on the digital pipe. Meanwhile, when the temperature is higher than a certain value (here set to 31 degrees Celsius), the buzzer will alarm. When less than this value, the alarm buzzer stops automatically. Test, you can touch DS18B20, its temperature rises to 31 degrees, observing phenomena.