On a Dynamic Display for Digital System Fault Detection

Abstract

A new and simple method is presented for fault detection of logic circuits. This method describes hexadecimal dynamic mapping, an alternative signature, of a digital system on the screen of an existing ordinary oscilloscope. This signature consists of a matrix of dots and ones, each dot and/or one representing the logic state of four channels, simultaneously. The number of channels may be increased to more than four at the expense of the simplicity of the hardware of the system that implements the system. The method, furthermore, lends itself to the generation of Karnaugh maps displayed on the screen of an oscilloscope for two or more variables. The true states of a Boolean function are displayed by ones while the false states by dots on this visual Karnaugh map. The generated map may be used in the minimization of combinatorial logic circuits, in the absence of other more advanced simulating techniques, or in the educational field for better comprehension of redundant circuits. The method presented herein, is based on the Lissajous patterns of digital signals, and it may also be used in matching digital signals and detecting phase difference and squareness of pulses, qualitatively.