Z8FS021 Datasheet, PDF (48/68 Pages) Zilog, Inc. – Select from an assortment of lenses and pyroelectric sensors to best fit your application

ZMOTION^® Intrusion Detection
Product Specification
40
Bit
Field
Control
Address
Table 20. PIR Process Rate
(ePIR_Process_Rate)
15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0
PIR Process Rate
Read
F3H
F4H
ePIR Process Rate (Bits 15–0)
Controlled by the PIR Engine.
• The PIR Process Rate Indicator is provided by the Engine to determine if the user application process
and interrupts overhead is impacting the performance of the Engine. If the Engine process rate drops
significantly, its ability to detect motion can be significantly reduced.This value is typicallyused at the
application development stage. This number gives an indication of how much CPU time the Engine
is receiving. Higher numbers are better. Generally, if the process rate drops below 0080h, the ability
to detect motion could be compromised.
Note: The 16-bit value provided by these two 8-bit registers must be read as an atomic operation by
the application. This read can be ensured by using either the CPU's ATM instruction or by disabling
interrupts while reading the two 8-bit registers.
Table 21. PIR Sample Size Register
(ePIR_Sample_Size)
Bit
7
6
5
4
3
2
1
0
Field
PIR Sample Size
Control
Read/Write
Address
F5H
PIR Sample Size (Bits 7–0)
Controlled by the application.
• This register controls the amount of averaging that the Engine performs on the incoming PIR signal
ADC samples. More averaging improves signal noise immunity at the cost of a slower sample rate.
PS028806-0315
Advanced API Register Set