7/17

PIR (PASSIVE INFRARED) DETECTOR USING ST7FLITE05/09/SUPERLITE

1.7.3 Hardware Self-Test

Hardware self-testing is performed each time the circuit is powered-ON or at microcontroller

reset. The hardware problem can be indicated by a dedicated LED (D1). In this test, the status

of the transistor Q1 (BC557) collector is checked with respect to the signal at the base of tran-

sistor Q3 (BC547) thus confirming the proper working of the transistor circuitry. LED(D1) gets

ON till hardware test routine executes.

1.7.4 LED Indicators

There are six LEDs (D1-D5,D7) in the circuit for indicating different status types, as explained

below:

1.7.5 Sensitivity Selection

The system can be made more or less sensitive by assigning high or small values to the pa-

rameters used to take movement detection decision. The parameters can be changed in a

function “select_sensitivity()” defined in “main.c”. At one time two values can be assigned to

the parameters and the selection for any value can be done by using jumper J8 (connected to

pin PB1 through a 10K

Ω resistor).

1.7.6 ICP connector

ICP (In circuit Programmer) connector can be used to program the device on the circuit.

LED

Purpose

Description

Led D1

Fault

This LED shows the result of hardware self test. LED Blinking indicates

some hardware (transistor circuitry) fault.

Led D2

Free

Available for user requirements. The port pin is configured as output

push-pull high.

Led D3

Heart Beat

It blinks to show that the microcontroller is working properly.

Led D4

Tamper indicator

LED ON means tampering occurred, selected by putting jumper J11

and removing J10.

Led D5

Movement

indicator

LED ON means human movement detected.

Led D7

Power supply

indicator

LED ON shows that the circuit is receiving power.