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Vol: 48(62) No: 1 / March 2003 Analogical versus Logical Keypad Interfaces for Microcontrollers Ports A. D. Potorac Department of Computers and Automation, Faculty of Electrical Engineering, University of Suceava, 9 University Street, 5800 Suceava, Romania, phone: +(4) 0722-627729, e-mail: alinp@eed.usv.ro, web: http://alin.usv.ro Keywords: analog ports, digital design, microcontrollers, interfacing, keypad, optimization. Abstract Interfacing keypads with microcontrollers’ port lines is classically represented by the well-known matrix structure, but many other solutions are available. Since new generations of microcontrollers are bringing new facilities, alternative solutions were proposed in order to obtain the maximum number of interface keys with minimum costs. Some of these solutions consist in using analog-to-digital interfaces instead of the logical I/O ports. Coding the keys with analog voltages involve A/D converters for decoding. Since analogue coding is usually based on cheap resistive dividers connected with the keypads, reading the keys voltage values could be done with comparators or A/D converters if included with the system. With appropriate software algorithm, low cost interface could be designed. The paper is suggesting some optimal solutions to do that. References [1] A. D. Potorac, “Digital Design Optimization for Bidirectional Ports of the Microcontrolers”, “Acta Electrotehnica”, Tehnical University Cluj-Napoca & Tehnical Sciences Academy of Romania, Cluj-Napoca, Vol. 44, No. 1, Ed. Mediamira, Cluj-Napoca, pp. 46 – 52, 2003. [2] A. D. Potorac, “Solutions to Minimize the Port Lines Number for Keypad Interfaces to Microcontrolers”, “SIELA 2003 – XIII-th International Symposium on Electrical Apparatus and Technologies”, Plovdiv, Bulgaria, Vol. 1, pp. 182 – 187, 2003. [3] A. D. Potorac, The Basis of Digital Design, Ed. Matrix Rom, Bucharest, 2002. [4] V. Velchev, “A Keypad Controller for Bi-directional Key Matrix”, Microchip “Design for Dollars”, DS40160A/4_012, 1997. [5] H. Taub and D. Schilling, Digital Integrated Electronics, McGrawHill, 1977. [6] Microchip Technical Library CD-ROM, 2002. [7] www.chipcenter.com/circuitcellar/askus/jun00. |