AVR单片机实现光电隔离RS-422/485智能接口研究

介绍了以AVR高速单片机AT90S2313为核心组成的串行口扩展方法及其软硬件实现方案.该方案可将微机的一个RS-232串行口扩展至4路光电隔离RS-422/RS-485串行口.根据控制方式的不同,4路RS-422/RS-485串行口可以单独或并行使用.在单片机控制下,能够自动识别通讯方式(10位、11位方式)和通讯波特率(1 200～115.2 k),可以在不改变微机已有控件的情况下,实现一个RS-232串行口与4路RS-422/RS-485串行口之间的全或半双工通信.实际应用表明,该方案实现的RS-232至4路RS-422/RS-485转换接口电路具有良好的性能及抗干扰能力.

Study on Intelligent Control RS-422/485 SCI Under the Mode of Photoelectricity Couping Based on AVR Singlechip

This paper introduces in detail an extending method of serial communication interface(SCI) and the software and hardware realization of the scheme. The extending SCI is mainly composed of singlechip AT90S2313 which has a higher operation speed. The scheme can extend one RS-232 SCI of PC to four RS-422/RS-485 SCIs under the mode of photoelectricity coupling. According to different control modes, the four RS-422/RS-485 SCIs can be used individually or parallelly. It can also distinguish automatically 10 bits from 11 bits communication mode and the communication baud rate from 1 200 to 115.2 k. It can realize duplex or semiduplex communication between one RS-232 SCI to four RS-422/RS-485 SCIs without necessarily changing the existing software of PC. The application result shows that the extending SCI circuit has a perfect performance and a good capacity of escaping disturbance.