针对当前LED交通诱导屏要求高可靠、高稳定、少维修的特点,本文将整块显示屏分为多个子区域,利用ZigBee无线网络对各子区域进行分布式控制.每个子区域作为一个ZigBee节点由一片CC2530控制实现显示、通信、检测等功能.所有节点硬件设计相同,均含高频核心板与低频底板.主控制模块与远程控制中心通信,生成各子区域的点阵显示数据并传送给协调器.使用Z-Stack协议栈在基于事件处理的多任务构架下设计了用户程序,实现了单播和广播通信,以及基于有限状态机的串口通信.高频核心板+低频底板的结构可降低PCB制板成本并提高电路板通用性和互换性.该设计增加了系统稳定性和可靠性,防止了故障扩散,减少了维修频度,还能将数据吞吐量分担到多个CPU上,使整个系统成为多核并行处理机.

According to the character of LED variable message sign which requires high reliability,high stability and less maintenance,in this paper,the whole LED variable message sign is divided into multiple sub areas,and ZigBee wireless network is applied in each sub-area to realize distributed control.Each sub-area becomes a ZigBee node which is controlled by CC2530 to complete display,communication,sensing and so on.The hardware design for every node is the same,which consists of high frequency core board and low frequency base board.Master control module communicates with remote control center,generates dot matrix display data for each sub-area and transmits these display data to coordinator.User program which is based on event process of multitask architecture is designed by employing Z-stack protocol.The user program includes point to point communication,broadcast communication and serial communication that is based on finite state machine.Structure of high frequency core board and low frequency base board is beneficial to lower manufacture cost of print circuit board and improve universality and interchangeability.This design enhances reliability and stability,avoids fault spread,reduces maintenance frequency,allocates total data throughout to multiple CPUs,makes the whole system become a multi-core processor.