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A State Machine Design for Binary Pattern Recognition

by James Antonakos

Start ý The Problem ý Enumeration ý State Diagram Approach ý A Little Synchronous Logic ý State Transition Table ý Let Karnaugh Maps Find the Patterns ý A Hotshot One-Shot ý The Real Thing ý Other Implementations ý I Challenge Youý ý Sources and PDF

A HOTSHOT ONE-SHOT

The push buttons used to enter zeroes and ones must be debounced to avoid multiple input bits from either button for a single press or release. This is where you get to interface a little analog circuitry with your digital machine (as done previously using the NOR gate to drive the indicator LED). Here, use the 555 timer connected as a monostable multivibrator (a one-shot), so that a single press or release of the push button generates a lengthy output pulse (around 250 ms) to overshadow the contact bounce. Figure 4 shows the associated 555 timer connections.

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