Abstract:
The ISM (Industrial, Scientific, and Medical) bands are established by treaty at the International Telecommunications Union (ITU) and are, therefore, allocated for primary use in most counties in the world, including Pakistan. The unlicensed ISM band has become one of the most active communication bands in the RF spectrum. Wireless LAN and Bluetooth devices operating in this band are secondary to the primary users of the band. Aside from these devices this band can be used to transmit a simple command signal to a remote receiver installed in the home at very low costs. In this paper, the author discussed design and implementation of simple low cost prototype for remote control of home appliances like light, fans, ac’s, fridges etc. In the developed prototype system, the command signal comprises of the device code, room code and the operation (i.e. ON/OFF or dim) to be performed. The master module that houses the RF receiver and a microcontroller interprets the signal and routes it to proper slave modules installed in the rooms, each having its own address. Master/slave communication is governed by RS-485 standard of serial communication to allow multipoint communication. Due to interferences caused by various sources, acknowledgement is necessary from master module receiver to R/F transmitter and from slaves to master module. Cyclic Redundancy Check (CRC) is used to provide error detection, and a retransmission is requested in the case of data corruption. The corresponding slave will capture the signal and perform the required operation on the device. As half duplex communication is utilized, the status of each room can be retrieved from the slave modules and can be shown in the remote control module on a LCD display, providing user friendly interface.
Page(s):
121-131
DOI:
DOI not available
Published:
Journal: New Horizons: Journal of the Institution of Electrical & Electronics Engineers Pakistan, Volume: 44, Issue: 1, Year: 2004