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

Figure 4. Main Routine Flowchart (Part 1 of 2)

Is ADC input

signal HIGH?

START

Set the biasing signal HIGH and provide

a delay to let the capacitor charge

No

Hardware Problem

Yes

Set the biasing signal LOW and provide

short delay to let capacitor discharge

Is ADC Input

signal LOW?

No

Yes

Set biasing Signal HIGH

Is ADC input

signal<

Threshold?

Yes

No

Make a buffer of 10 integers to store 10 consecutive values of Low_var

Low_var: A variable that counts the number of times that were needed to make

the biasing signal LOW to keep the ADC input signal at threshold level (3V in the

software).This is done in the Timer ISR.

Enable Timer (AR Timer) Interrupt

with interrupt time 52µs

Hardware

check

Stabilization

A