Z8FS021 Datasheet, PDF (45/68 Pages) Zilog, Inc. – Select from an assortment of lenses and pyroelectric sensors to best fit your application

ZMOTION^® Intrusion Detection
Product Specification
37
Buffer Refresh (Bit 4)
Uses a fast fill algorithm to quickly refill the motion detection buffers; controlled by the application.
• This bit is used to restart motion detection by quickly reinitializing and refilling the motion detection
constructed sample buffers. This can be used as a method to restore motion detection after waking
up from sleep mode or it can be used to help ignore external events that can cause false detections.
• Waking up from Sleep Mode
If this bit is set when the EPIR_INIT macro is executed the Engine re-fills the constructed sample
buffers with a fast fill algorithm that allows it to quickly restore motion detection. Typically, a simple
external wake-up circuit would be implemented that provides an unqualified motion detection signal
to wake up the MCU from Sleep mode (SMR). Upon SMR, the application would set the Buffer
Refresh bit, execute EPIR_INIT, and then continue with normal motion detection functions for some
period of time before returning to Sleep mode. By setting this bit prior to EPIR_INIT, the Engine
buffers are filled much faster enabling it to analyze the original signal seen by the external wake up
circuit and determine if it is 'real' motion.
• Ignoring False Detection Events
If the MCU is used to control external components (LED's, relays, Lights, Triac's, etc) a fluctuation on
the power supply can be created as the external device is turned on or off. The Buffer Refresh bit can
be used to ignore any false detection that could be created by these fluctuations. When the external
device is turned on or off, the application can set the Buffer Refresh bit to effectively reset the motion
detection history and therefore ignore any effect from the external device.
New Sample (Bit 3)
New sample available from PIR Signal High/Low register; set by the PIR Engine, cleared by the
application.
• This bit indicates that the PIR Engine has a new sensor signal input sample available that can be read
by the application. This status is available as an advanced feature as the application is not normally
required to read the sampled PIR sensor signal. The application must clear this bit when the sample
has been read.
MD Origin (Bit 2)
Origin of last motion detection event; controlled by the PIR Engine.
• This bit indicates how the PIR Engine detected the last Motion Detected Event. When the Engine sets
the Motion Detected bit in ePIR_SC0, it also sets this bit according to which detection Engine
registered the event.
0 = Normal Motion Detector
1 = Extended Motion Detector
EM Noise Detected (Bit 1)
New sample available from PIR Signal High/Low Register; set by the PIR Engine, cleared by the
application.
• This bit indicates that the PIR Engine has a new sensor signal input sample available that can be read
by the application. This status is available as an advanced feature as the application is not normally
required to read the sampled PIR sensor signal. The application must clear this bit when the sample
has been read.
PS028806-0315
Advanced API Register Set