温度监视器，通过按键来设定温度上下限，用DB18B20来显示温度，越限灯亮，蜂鸣器响，在KEILC下编译调试成功-Temperature monitor, through the button to set the temperature of the upper and lower limits, DB18B20 used to display the temperature, the more limited light, buzzer sound, in the debug compile