Z8FS021 datasheet(61/68 Pages) ZILOG

61 / 68 page

PS028806-0315

Appendix A. Example Application Schematics

ZMOTION® Intrusion Detection

Product Specification

Z8FS021xHJ20EG (28-Pin)

Examples of single and dual pyro circuit designs employing the 28-pin ZMOTION Intru-

sion Detection MCU are described in this section.

Single Pyroelectric Sensor

Figure 10 shows an example circuit for the 28 pin device of the ZMOTION Intrusion

Detection MCU with a single pyroelectric sensor. The interface to the pyroelectric sensor

is via the dedicated input ANA2 (pin 1). VREF (pin 3) must be externally tied to ANA3

(pin 4). This is considered Internal VREF and bit 7 of PIR_ASC0 is set to '0' since it is

being generated by the internal voltage reference. If an externally generated voltage refer-

ence is to be used, tie it directly to ANA3 (pin 4) and VREF, (pin 3) and set bit 7 of

PIR_ASC0 to '1'.

The status LED is driven by pin 28 (PB1/ANA1) which is normally configured as a GPIO

by the application to control the state of the LED. When White Light Detection is enabled,

the PIR Engine automatically reconfigures this pin to an ADC input to perform the neces-

sary ADC conversion and returns it to a GPIO when done.

Pin 22 is dedicated as the Debug pin and is connected to pin 4 of the Debug Header. Pin 21

is set up for the Reset function, but can also be used as PD0 (general purpose I/O) as the

application requires. Pull-up resistors (10K) are provided on the Debug and Reset signals

as required for the Debug interface. All other signals can be used as required.

The power supply design remains available to application requirements.

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