ABSTRACT

This chapter deals with the principles, construction and design methodology of real-time clocks (RTCs) and data communication protocol programming. It explains digital circuit design for interfacing many specialized sensors that follow the two-wire interface (TWI), SPI, I2C interface, global system for mobile (GSM) communication Wr/Rd interface, GPS interface, video graphics array (VGA) interface and Ps/2 interface for data transmission, initialisation, resetting, writing/reading measurement data, monitoring a battery level and so on. Interfacing protocols, necessary digital architecture and timing diagrams required for operating a DS12887 are presented. The interfacing protocol of two measurement sensors, SHT11 for temperature and relative humidity and SCP1000D for atmospheric pressure, and the digital architecture needed for their operation and measurement of parameters are explained, with state diagrams. Design exercises are listed in the last section.