Z8FS021 datasheet(26/68 Pages) ZILOG

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PS028806-0315

Hardware Connection Requirements

ZMOTION® Intrusion Detection

Product Specification

Hardware Connection Requirements

This section describes the required external hardware connection for the ZMOTION MCU

Series. See Appendix A. Example Application Schematics on page 49 for example sche-

matic diagrams showing these connections.

Pins are automatically configured to their required function when the PIR Engine is initial-

ized via the EPIR_INIT macro. The device can be operated in Single Pyro Mode when

supporting one pyroelectric sensor or in Dual Pyro Mode when supporting two pyroelec-

tric sensors. Both of these modes can be operated in Normal or Low Scan Rate modes.

Depending on the application, there can be up to four connection requirements supporting

these modes: one for each of two PIR sensors, one for the ADC and one for the White

Light Detection and Status LED. A description of each of these elements follows in this

section. For a broader description of the White Light Detection component, see the White

Light Detection section on page 19.

Pyroelectric PIR Sensor #1

The signal from the PIR sensor is connected directly to the ANA2 input of the ADC. The

ADC is configured for differential buffered mode by Zilog’s PIR technology. The sensor

signal should be connected directly to the ADC input with no additional signal condition-

ing circuitry unless specified by the pyroelectric sensor manufacturer.

ADC V

REF

The on-chip VREF is configured for 1V of nominal voltage. The PIR Sensor signal is con-

nected to the positive (+) differential input of the ADC (ANA2), and the VREF signal is

connected to the negative (–) differential input (ANA3). The 8-pin device provides an

internal connection from VREF to ANA3 to support this configuration; therefore, no exter-

nal hardware connection is required. The 20- and 28-pin devices require an external con-

nection from the VREF output signal to the ADC negative (–) (ANA3) input.

Pyroelectric PIR Sensor #2

In Dual Pyro Mode, the ADC is still used in differential buffered mode (i.e., as is true for

Single Pyro Mode). The signal from the second PIR sensor is connected to ANA3. The

28-Pin Device Pin 1 (ANA2) is reserved as the analog ADC input from the pyroelectric sensor. In Single

Pyro Mode, Pin 4 (ANA3) must be externally tied to V

REF on Pin 3 (PB5/ VREF). PB5 will

be configured as V

REF output by the PIR Engine when it is enabled.

In Dual Pyro Mode, which supports 2 pyroelectric sensors, Pin 4 (ANA3) is used for the

second sensor. In this mode the Pin 3 V

REF signal is not connected externally to any

other ADC inputs and is therefore available to the application (PB5/V

REF).

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