说明：  一个数字电压表，利用LCD显示测量结果，测量信号为实验箱提供的电位器输出AN0，用ADC0809进行电压信号采样。设计程序，可实现以下所有功能： 1)将采样信号值0~FFH直接利用LED灯L1~L8显示。LED显示信号接口可用P1口或74LS273或8255，请自行选择硬件并接线。 2）将采样信号值0~FFH转换为0.000~5.000V，并在LCD屏幕上显示。
(A digital voltmeter is designed, and the measurement results are displayed by LCD. The measured signal is the output AN0 of the potentiometer provided by the experimental box, and the voltage signal is sampled with ADC0809. A design program that implements all of the following functions:a. the sampling signal value 0~FFH is directly displayed by the LED lamp L1~L8. LED display signal interface available P1 port or 74LS273 or 8255, please choose the hardware and wiring.b. convert the sampled signal value 0~FFH to 0.000~5.000V and display it on the LCD screen.)