Z8FS021 Datasheet, PDF (47/68 Pages) Zilog, Inc. – Select from an assortment of lenses and pyroelectric sensors to best fit your application

ZMOTION^® Intrusion Detection
Product Specification
39
Bit
Field
Control
Address
Table 19. PIR Advanced Status/Control Register 2
(ePIR_ASC2)
7
6
5
Lock Level
R/W
4
3
Window Size
R/W
F2H
2
1
0
Window Update Rate
R/W
Lock Level (Bits 7–5)
Controlled by the application.
• This parameter sets the minimum slope change in the signal that can be considered valid motion. This
prevents small signal changes caused by environmental or V_CC shifts from causing a false detection.
Use this value in combination with PIR Sensitivity and Range Control settings to balance sensitivity
and stability to the particular lens and pyroelectric sensor being used.
– Smaller values allow subtle signals with lower slopes to be considered motion events at the
expense of potential false motion events.
– Larger values allow the system to ignore smaller signal slope changes at the expense of potentially
missing smaller motion events.
Window Size (Bits 4–3)
Controlled by the application.
• This register determines the size of the control limit window. A larger window size produces more
stable control limits at the cost of additional CPU usage. If a smaller window size is used, the more
frequently the window can be calculated which allows it to track the signal better.
00 = Reserved.
01 = Small window.
02 = Medium window.
03 = Large window.
Window Update Rate (Bits 2–0)
Controlled by the application.
• This register determines how frequently the control limits are calculated. It is measured in PIR
samples. A smaller number produces more frequent calculations which allow the control limits to track
the signal better, at the cost of increased CPU usage. The valid range is 0 to 7.
• The window is updated every 4 + (Window Update Rate * 2) PIR samples.
PS028806-0315
Advanced API Register Set