程序P5口连接的是共阳极数码管，所有段的发光管正极连在一起接+5V，P5口控制各段发光管的负极。其中库文件根据不同实验台而不同。-The procedures P5 port is common anode digital tube, all segments of the light-emitting tube cathode together then+5V P5 port to control the negative of each segment of the light-emitting tube. So, you want to let a certain period of the luminous tube lights up P5 port to send a logical " 0"　period extinguished should be sent to the logic " 1" . Which library files under different experimental station.