A Potential Difficulty in A/D Conversion Using Microcomputer Systems

Special precautions are urged upon designers and users of A/D conversion systems based on laboratory microcomputers. Even when normal design procedures and manufacturer specifications are conscientiously followed in organizing the hardware, serious degradation of A/D system performance can result from synchronous noise generated by the controlling software, unless that software is properly configured to minimize execution of noisy instructions at critical times. Simple procedures are outlined to test for the presence of such effects.