A simple software lowpass filter suits embedded-system applications

摘要

BUILDING A DIGITAL EQUIVALENT OF AN ANALOG LOWPASS RC FILTER REQUIRES JUST A COUPLE OF LINES OF FIXED-POINT C CODE. Hardware-design engineers have long recognized the usefulness of RC lowpass filters (Figure 1). Lowpass filters are useful for performing signal conditioning, removing noise from a signal, or rejecting unwanted signals. The first-order recursive filter is the digital equivalent of the RC filter, and, as the ratio of the sample frequency to the bandwidth increases, their responses become identical.