Chapter 15

Serial Communications


There are a wide variety of serial communications protocols available, but all rely on some form of coding scheme to efficiently and effectively transmit the serial data across the transmission medium. In this chapter, not only will the common methods of transmitting data be reviewed (RS232 and USB), but in addition some useful coding mechanisms will be described (Manchester, Code Mark Inversion, Non-Return-to-Zero-NRZ, Non-Return-to-Zero-Inverted-NRZI) as they often are used as part of a higher level transmission protocol. For example, the NRZI coding technique is used in the USB protocol.


Serial link



Manchester encoding



15.1 Introduction

There are a wide variety of serial ...

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