Z8FS040 datasheet(34/56 Pages) ZILOG

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ZMOTION

TM Detection and Control Family

Product Specification

PS028506-1110

PRELIMINARY

PIR Advanced Status/Control Register 0 (ePIR_ASC0)

Bit

Field

Reserved

Buffer

Refresh

New

Sample

Origin

EM Noise

Detected

Transient

Detected

Control

R/W

Address

F0H

Buffer Refresh (Bit 4)

Uses fast fill algorithm to quickly refill the motion detection buffers.

Controlled by 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 may 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 PIR engine, cleared by application

This bit indicates that the PIR engine has a new sensor signal input sample available that may 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.

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