Analog transducer circuit with digital control

Abstract From the Canadian patent

A two wire transmitter controls loop current as a function of a sensed parameter such as pressure or temperature using analog sensing and signal processing circuitry. Corrections such as, for zero, span, and linearity are provided in the form of analog correction signals by a digital circuit which includes a nonvolatile memory a, microcomputer , and a digitial-to-analog (D/A) converter . The microprocessor controls the D/A converter as a function of stored digital correction values to produce the analog correction signals used by the analog signal processing circuitry to control the magnitude of the loop current flowing through the two wire transmitter