用2片DB18B20测量温度，0.5秒刷新一次显示在PC机上，格式为“T1=温度1,T2=温度2,A=平均值”。单片机与PC机用MAX232连接。-Temperature measurement using two DB18B20, 0.5 second refresh time displayed on the PC, the format of " T1 = Temperature 1, T2 = temperature 2, A = average."　With a MAX232 chip and PC connection.