Z8FS040 Datasheet, PDF (28/56 Pages) Zilog, Inc. – ZMOTION Detection and Control Family Featuring Zilog’s PIR Technology

ZMOTION^TM Detection and Control Family
Product Specification
PIR Stable (Bit 0)
Passive Infrared (PIR) sensor signal stabilized bit
Controlled by PIR engine
After periods of non-use the PIR sensor will take some time to stabilize before it can be used reliably.
The amount of time is dependant on the PIR Sensor being used and environmental conditions and can
range from a few seconds up to a minute. To relieve the application S/W from having to assume the
worst case stabilization time, the PIR engine automatically monitors the DC offset of the PIR sensor and
sets this bit when it determines that it has become stable. This bit indicates that the PIR sensor has
stabilized after one of the following conditions:
- After initial power on (cold start).
- After re-enabling the Engine via PIR Enable Register.
- After returning from sleep mode.
0 = PIR sensor signal is not stable, motion detected events are not valid
1 = PIR sensor signal is stable, motion detected events are valid
PIR Status/Control Register 1 (ePIR_SC1)
Bit
7
6
5
4
3
Field
Control
Address
Engine
Timer
Tick
R/W
Frequency Response
Read/Write
103H
2
1
PIR Scan
Rate
Reserved
R/W
0
0
Dual
Pyro
Enable
R/W
Engine Timer Tick (Bit 7)
PIR One Second Timer Tick
Set by Application; cleared by PIR engine
This bit must be set to 1 once per second by the user application. This provides the engine with a one-
second tick to perform house keeping operations relating to the motion detection. The engine will
routinely poll this bit to obtain a one-second tick. This bit is cleared by the engine.
0 = Cleared by PIR engine
1 = One-Second interval has occurred
Frequency Response (Bits 3-6)
Frequency Response of PIR engine
Controlled by Application
Range: 0h - Ch
This value determines the frequency response of the motion detection system. Higher values allow
lower frequencies to be accepted by the PIR engine. Lower values cause the Engine to ignore targets
that generate lower frequencies. These targets typically include horizontally oriented objects such as
pets.
The frequency of the signal that is presented to the PIR engine is largely dependent on the structure of
the PIR lens being used (number and dispersion of beams). A lens with several evenly distributed
beams provides better frequency response performance than a lens with an uneven beam distribution.
Note: Lower programmed values also have the effect of reducing the relative range of detection.
PS028506-1110
PRELIMINARY
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