Z8FS021 datasheet(24/68 Pages) ZILOG

24 / 68 page

PS028806-0315

Peripherals

ZMOTION® Intrusion Detection

Product Specification

UART

Oscillator Control

All devices can be operated with the internal 5.54MHz IPO. For applications that require

more processing power or a more accurate time base, an external crystal oscillator or

ceramic resonator can be used.

When using the 8-pin device, external oscillator support is limited to Single Pyro Mode

only, because ANA3 (the ADC input for a second pyro sensor) is multiplexed with XOUT.

The 20- and 28-pin devices can be operated with an external oscillator in both Single and

Dual Pyro modes.

Do not operate at frequencies lower than the IPO frequency while the PIR Engine is en-

abled or motion detection performance will be degraded.

No other changes or limitations are placed on oscillator control functions by the PIR

Engine.

Flash Memory

The control registers associated with Flash memory are all available to the application.

The PIR Engine uses the value programmed into the Flash Frequency registers (FFREQ)

to determine the required sample rate of the ADC and other functions. The Flash Fre-

quency High (FFREQH) and Flash Frequency Low Byte (FFREQL) registers must be pro-

grammed prior to initializing the PIR Engine. These two registers combine to form a 16-

bit value, FFREQ. This value is the System Clock Frequency in KHz and is calculated

using the following equation.

FFREQ[15:0] = {FFREQH[7:0],FFREQL[7:0]} = (System Clock

Frequency)/1000

8-Pin Device

/CTS0 is configured as ANA2 to support the signal

input from the Pyroelectric sensor. It is therefore not

available to the user application. The UART is still

able to function correctly without /CTS when CTSE in

the U0CTL0 Register is set to 0.

20-Pin Device All external UART functions are available for the user

application.

28-Pin Device All external UART functions are available for the user

application.

Caution:

Z8FS021 Datasheet(PDF) 24 Page - Zilog, Inc.