ZEPIR0BAS02MODG datasheet(18/78 Pages) ZILOG

18 / 78 page

PS030504-0917

Operation

ZMOTION® Detection Module II

Product Specification

Operation

When power is applied, the TXD/SNS pin is sampled to determine the mode of operation.

If the signal is above 2.5V, Serial Interface Mode is entered. If the signal is between 0V

and 1.8V Hardware Interface Mode is entered. During this time, the pyroelectric sensor is

monitored, and the device waits for it to stabilize. After this stabilization period is com-

plete, the device starts normal operation in the selected mode. In Hardware Interface

Mode, the DLY, SNS, LG and SLP signals are sampled regularly. In Serial Interface

Mode, TXD/RXD are used to communicate with the device and LG, SLP and MD also

provide their defined functions.

Hardware Interface Mode

This mode of operation is selected when the SNS pin is at a value between 0V and 1.8V

during power ON (or after a reset caused by VBO). After Hardware Interface Mode has

been established, this pin becomes the sensitivity input and accepts a voltage between 0V

and 1.8V to set the motion detection sensitivity level.

• 0V = highest sensitivity

• 1.8V = lowest sensitivity

These sensitivity levels are normally achieved with a simple resistor divider or potentio-

meter resistor divider.

After application of power, the PIR sensor is allowed to stabilize. At this point, the MCU

waits for the PIR sensor to stabilize; this period is typically 20 seconds but varies depend-

ing on environmental conditions. The software dynamically monitors the pyroelectric sen-

sor during power up and begins detecting motion as soon as the sensor is stable.

The MD (Motion Detect) pin is driven active (Low) when motion is detected. The dura-

tion in which the signal remains active is determined by the voltage on the delay pin and

can be set to a value between 2 seconds and 15 minutes. See Table 2 on page 5.

The Light Gate signal acts as a disable (gate) for the MD signal. In a typical application,

this signal is a representation of the ambient light in the environment. If there is light

detected, the MD signal does not activate, even in the presence of motion. For an example

showing how to use ZDMII in Hardware Interface Mode, see Appendix B. Hardware

Interface Mode on page 63.

ZEPIR0BAS02MODG Datasheet(PDF) 18 Page - Zilog, Inc.