PIC16F887A单片机A/D转换程序，RA2接AD模拟电压，当输入电压大于2.5V时发出报警型号，与PORTD相连的8个LED数码管闪烁；当电压小于2.5V时，发光管停止闪烁，且只有低4个发光 。-The the PIC16F887A microcontroller A/D conversion process, RA2 then AD analog voltage alarm when the input voltage is greater than 2.5V Model 8 LED digital tube connected to PORTD flashing　when the voltage is less than 2.5V, LED stops flashing, and only The low four light-emitting.