Digital Multiplexing of Analog Data in a Microprocessor Controlled Data Acquisition System

An analog data acquisition system typically consists of an analog multiplexor followed by an analog to digital (A/D) converter. An alternative configuration uses multiple comparators (one per input) followed by a digital multiplexor. If the control functions for A/D conversion are incorporated into a microprocessor, several potentially interesting data acquisition and conversion strategies are available. At first thought, an interrupt-driven conversion process which simultaneously searches all inputs in parallel for a level match appears attractive. However, analysis shows that a sequential conversion of the inputs, one at a time, using the successive approximation algorithm, is usually superior.