ABSTRACT
This chapter covers the construction of more sophisticated combinational and sequential real-world interfacing circuits. In this chapter, the interfacing digital logic includes A/D converters; optical and temperature sensors; universal asynchronous receiver transmitters (UARTs); multichannel data logging; bidirectional A/D converters; optical beam tracking, aligning and positioning; RF Tx/Rx; pseudorandom binary sequence (PRBS) generators; time division multiple access (TDMA) and low/high voltage D/A converters. The examples show how to transform conceptual ideas into real-time working systems/modules. This chapter begins by discussing the basic signal conditioning unit and simple sensor interfacing modules. The requirements of single-channel/multichannel, unidirectional/bidirectional, low/high voltage A/D converters, their working principles, associated terminologies, interfacing protocols and timing diagrams are described. In the same way, unidirectional/bidirectional D/A converters are also explained. Interfacing protocols of different sensors and physical parameters, like optical power, temperature, strain and magnitude and measurement methodologies using them are also detailed, with design examples. Data acquisition and logging in a computer through the RS232 (DB-9 connector) serial port using the UART protocol is explained, with digital architecture and data transmission/synchronisation frame formats. The working principles of optical position detector (OPD) interfacing, monopulse computation and plotting the optical beam position profile are detailed. Design examples for a remote-control IR/RF encoder/decoder, parallel/serial PRBS generator, Kasami sequence generator, analogue TDMA, M-array pulse amplitude modulation (PAM) and “SIN”/”COS” signal generators are presented.
