STC89c52开发板原理图，PCB图，含有AD格式原理图和PCB图，LED,动态7段数码管，蜂鸣器，4*4矩阵键盘，rs232串口，PL2303usb串口，适合学习单片机的朋友-STC89c52 development board schematic, PCB diagram, containing the AD format schematic and PCB diagram, LED, dynamic 7 segment digital tube, buzzer, 4*4 matrix k