Z8FS021 Datasheet, PDF (38/68 Pages) Zilog, Inc. – Select from an assortment of lenses and pyroelectric sensors to best fit your application

ZMOTION^® Intrusion Detection
Product Specification
30
PIR Scan Rate (Bit 2)
PIR ADC conversion rate for the Pyroelectric Sensor; controlled by the application.
• The PIR Engine performs the necessary ADC conversions on the PIR sensor input. Each conversion
generates an interrupt that is processed by the PIR Engine from the EPIR_ADC_ISR macro. The PIR
Scan Rate bit determines the rate at which the ADC conversions are generated.
• In Normal Scan Rate Mode (PIR Scan Rate set to 0), the Z8FS021 ADC peripheral is set to
continuous conversion mode which causes a conversion to be carried out automatically every 256
system clocks. In this mode, the application is only required to execute the EPIR_ADC_ISR macro
for each ADC interrupt. The ADC continually runs and continuously generates interrupts.
• When Low Scan Rate Mode is selected by setting this bit to a 1, continuous conversion mode is
disabled and the ADC is operated in single-shot mode such that each conversion takes 5129 system
clocks to complete. In this mode, the application software must initiate the ADC conversion request
(set bit 7 of ADCCTL0) and execute the EPIR_ADC_ISR macro once every 5 ms.
• In Low Scan Rate Mode, the ADC is disabled between conversions to reduce power consumption.
Power consumption can be reduced further if the application software uses this mode in conjunction
with the CPU’s Halt or Stop modes. Alternately, this mode can be used to provide the application
software with additional CPU processing time.
• Although the Low Scan Rate Mode provides the application with more processing power and the
opportunity for the system to reduce power consumption, the normal scan rate will provide better
sensitivity and range. While operating in Low Scan Rate Mode, sensitivity is reduced by
approximately 20%. The performance of Direction Detection can also be reduced in this mode. EMC
immunity is disabled while in Low Scan Rate Mode.
• EMC immunity features, such as transient sensitivity and noise sensitivity, are disabled while in Low
Scan Rate Mode.
• If the PIR Scan Rate bit is changed during Engine operation, the Engine will stop detecting motion for
up to 200 ms to avoid potential false motion detection. When changing the PIR Scan Rate mode, the
Advanced API registers must first be updated with the appropriate values.
0 = Normal Scan Rate Mode
1 = Low Scan Rate Mode
2-Pulse Enable (Bit 1)
2-Pulse Detection Mode Enable; controlled by application
This bit determines if motion detection requires one or two motion pulses as the target passes across
the beams created by the Fresnel lens. With a Pulse Count of 1, a single motion pulse from the target
is required to qualify as valid motion. A Pulse Count of 2 requires two motion pulses from the target –
one positive and one negative – to qualify as valid motion. A Pulse Count of 2 is typically used in
harsher environmental conditions to decrease the chances of false triggers from sources such as fast
heating and cooling.
0 = One pulse of motion required for detection.
1 = Two pulses of motion required for detection.
PS028806-0315
Standard API Register Set