Multiple Inputs and Outputs in Embedded Systems

Abstract

Input of many states from multiple mechanical contacts to an Embedded System, as well as outputs to many leds, pose a challenge for the design of an embedded system due to the small number of Input/Output (I/O) pins that most Microcontrollers have. On the other hand, although it is quite simple to debounce a single mechanical contact, the problem becomes more complex in the case of multiple contacts, which usually have different bouncing times. There are many known I/O methods that deal with multiple contacts. This work aims to explain and analyse them in an integrated manner. It also proposes a different way, which provides the possibility of connecting many inputs and outputs, with only three ports. Two methods to debounce multiple mechanical contacts are discussed. Finally, an innovative modular way of cabling many contacts along a house, or enterprise, is presented.