PSoC Analog Coprocessor Pioneer Kit Guide, Doc. # 002-11190 Rev. *B
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Kit Operation
Most of the common PIR motion sensors have two or four sensing elements. These elements are
arranged such that the voltage generated by one is subtracted by the other. This arrangement
cancels the common signal and generates a voltage only when there is a difference in the incident
infrared radiation level on the sensing elements.
shows the dual-element PIR motion sensor with the elements connected in series but
with an opposite phase, because of which it has the maximum sensitivity along a particular axis.
Figure 3-7. PIR Motion Sensor Dual-Element
The sensor package is designed to have a unique field-of-view for each element. When an IR
radiating source moves across the fields of view, the sensor generates a differential signal (see
). For a 90° field-of-view or more, a Fresnel lens is mounted on the PIR motion sensor. It
improves the sensitivity and thus the detection distance.
Figure 3-8. PIR Motion Sensor Output Response
