Z8FS021 datasheet(48/68 Pages) ZILOG

48 / 68 page

PS028806-0315

Advanced API Register Set

ZMOTION® Intrusion Detection

Product Specification

Table 20. PIR Process Rate

(ePIR_Process_Rate)

Bit

9876543210

Field

PIR Process Rate

Control

Read

Address

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 abilityto 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

76543210

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.

Z8FS021 데이터시트(PDF) 48 Page - Zilog, Inc.