Among other interface problems, contact bounce complicates the connection of mechanical contacts or any noisy digital input signal to a microcontroller. Although designers have proposed a variety of hardware and software approaches that address the problems that contact bounce poses, no one has yet claimed a definitive and predictably stable approach. (For a sampling of approaches, see references 1 through 10.) The usual hardware approach to eliminating contact bounce comprises an RC filter followed by a Schmitt tr igger (Figure 1). You can extend the filter's effectiveness simply by increasing the RC time constant at the expense of increased response time.
展开▼
