Z8FS040 datasheet(17/56 Pages) ZILOG

17 / 56 page

ZMOTION

TM Detection and Control Family

Product Specification

PS028506-1110

PRELIMINARY

ADC

Zilog’s PIR technology requires exclusive access to the ADC peripheral in order to detect

motion. However, ADC conversions can be requested by the application through the API (PIR

Status/Control Register 3). If it is necessary for the user application to utilize the ADC

peripheral directly, the PIR engine must first be disabled via the PIR Engine Enable Register in

the API. Motion detection is not possible while the PIR engine is disabled. When the user

application is finished with the ADC peripheral, it must re-enable the PIR engine.

8 Pin Device: PA3 (ANA2) is reserved as the analog ADC input from the pyroelectric sensor.

Therefore ANA2 is not available for user applications. Additionally ANA3 is used for second

sensor input in dual pyro mode. All other channels are available to the user application.

ADC Channel

Available to Application

Yes

Only in Single Pyro Mode

20 Pin Device: PB2 (ANA2) is reserved as the analog ADC input from the pyroelectric sensor.

Therefore ANA2 is not available for user applications. Also, ANA3 and ANA6 are not available

since PB3 (ANA3) must be tied directly to PC2 (ANA6/ VREF). PC2 is configured as VREF output

by the PIR engine. In dual pyro mode ANA3 is used for second sensor input – rather than

being tied to VREF and therefore ANA6/ VREF becomes available. All other channels are

available to the user application.

ADC Channel

Available to Application

Yes

Only in Dual Pyro Mode

28 Pin Device: PB2 (ANA2) is reserved as the analog ADC input from the pyroelectric sensor.

Therefore ANA2 is not available for user applications. Also, ANA3 is not available since it is

tied directly to PB5/ VREF. PB5 will be configured as VREF output by the PIR engine. In dual pyro

mode ANA3 is used for second sensor input – rather than being tied to VREF and therefore PB5

becomes available. All other channels are available to the user application.

ADC Channel

Available to Application

Yes

Z8FS040 Datasheet(PDF) 17 Page - Zilog, Inc.