The Design of Isolated RS485 Bus System Based on ATmega162

As a multipoint differential data transmission electrical specification, RS485 bus has become the industry one of the most widely used standard communication interface. This communication interface allows the simple multi-point two-way communication on a pair of twisted pair, with which the noise suppression capability, data transfer rate, cable length and the reliability is unmatched by other standards. But this way of differential signal transmission is highly susceptible to common-mode interference, EMI electromagnetic interference and strong signal interference. In this paper, optical isolation devices were adopted on RS485 bus, which can effectively solve the interference problem of signal transmission process.