max7219实现单片机对数码管的显示，单片机3个I/O口就可以实现，减少了对单片机的引脚的需求-max7219 tube to achieve single-chip digital display, 3 single-chip I/O port can be achieved to reduce the pin on the MCU needs

重要芯片资料 好好珍惜 简单明白 内容详细-Important chip cherish simple to understand information and detailed