Z8FS040 Datasheet, PDF (34/56 Pages) Zilog, Inc. – ZMOTION Detection and Control Family Featuring Zilog’s PIR Technology

ZMOTION^TM Detection and Control Family
Product Specification
PIR Advanced Status/Control Register 0 (ePIR_ASC0)
Bit
7
6
5
4
3
Field Reserved Reserved Reserved
Buffer
Refresh
New
Sample
Control
0
0
0
R/W
R/W
Address
F0H
2
MD
Origin
R
1
EM Noise
Detected
R/W
0
EM
Transient
Detected
R/W
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.
PS028506-1110
PRELIMINARY
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