数字电压表该利用单片机AT89S51与ADC0809设计一个数字电压表，能够测量0－5V之间的直流电压值，四位数码显示，但要求使用的元器件数目最少。-Digital voltage meter to the use of microcontroller AT89S51 with the design of a digital voltmeter ADC0809, capable of measuring 0-5V DC voltage between the value of four digital display, but requires the use of a minimum number of components.