An incremental rotary encoder with quadrature outputs enables a system to detect rotational speed, angular displacement and direction of rotation. The output usually comprises two square waves that generate a pulse each time a mark is detected on the sensor’s code wheel.
The encoder’s resolution must be known to calculate the speed and angular displacement. Although resolution is often expressed in terms of Pulses Per Revolution, other terms such as periods, cycles or lines may be used. If the resolution is described in terms of Counts Per Revolution, users need to be aware that a 2-bit quadrature output produces four counts per cycle. It is important to take care when reading the datasheet, particularly if the acronym CPR is used, to understand whether the manufacturer means cycles or counts per revolution.
CUI has several families of optical, mechanical and capacitive incremental rotary encoders and in this CUI Insights™ blog, Jason Kelly provides advice to help designers interpret encoder datasheets correctly to ensure accurate speed and displacement calculations.
Credit: Jason Kelly, CUI