2.2.7 PIR

Introduction

In this project, we will make a device by using the human body infrared pyroelectric sensors. When someone gets closer to the LED, the LED will turn on automatically. If not, the light will turn off. This infrared motion sensor is a kind of sensor that can detect the infrared emitted by human and animals.

Required Components

In this project, we need the following components.

../_images/list_2.2.4_pir2.png

It’s definitely convenient to buy a whole kit, here’s the link:

Name

ITEMS IN THIS KIT

LINK

Raphael Kit

337

Raphael Kit

You can also buy them separately from the links below.

COMPONENT INTRODUCTION

PURCHASE LINK

GPIO Extension Board

BUY

Breadboard

BUY

Jumper Wires

BUY

Resistor

BUY

RGB LED

BUY

PIR Motion Sensor Module

-

Schematic Diagram

../_images/image327.png

Experimental Procedures

Step 1: Build the circuit.

../_images/image214.png

Step 2: Go to the folder of the code.

cd ~/raphael-kit/c/2.2.7/

Step 3: Compile the code.

gcc 2.2.7_PIR.c -lwiringPi

Step 4: Run the executable file.

sudo ./a.out

After the code runs, PIR detects surroundings and let RGB LED glow yellow if it senses someone walking by.

There are two potentiometers on the PIR module: one is to adjust sensitivity and the other is to adjust the detection distance. To make the PIR module work better, you You need to turn both of them counterclockwise to the end.

../_images/PIR_TTE.png

Note

If it does not work after running, or there is an error prompt: wiringPi.h No such file or directory, please refer to Install and Check the WiringPi.

Code

#include <wiringPi.h>
#include <softPwm.h>
#include <stdio.h>
#define uchar unsigned char

#define pirPin    0     //the pir connect to GPIO0
#define redPin    1
#define greenPin  2
#define bluePin   3

void ledInit(void){
    softPwmCreate(redPin,  0, 100);
    softPwmCreate(greenPin,0, 100);
    softPwmCreate(bluePin, 0, 100);
}
void ledColorSet(uchar r_val, uchar g_val, uchar b_val){
    softPwmWrite(redPin,   r_val);
    softPwmWrite(greenPin, g_val);
    softPwmWrite(bluePin,  b_val);
}
int main(void)
{
    int pir_val;
    if(wiringPiSetup() == -1){ //when initialize wiring failed,print message to screen
        printf("setup wiringPi failed !");
        return 1;
    }
    ledInit();
    pinMode(pirPin, INPUT);
    while(1){
    pir_val = digitalRead(pirPin);
        if(pir_val== 1){ //if read pir is HIGH level
            ledColorSet(0xff,0xff,0x00);
        }
        else {
        ledColorSet(0x00,0x00,0xff);
        }
    }
    return 0;
}

Code Explanation

void ledInit(void);
void ledColorSet(uchar r_val, uchar g_val, uchar b_val);

These codes are used to set the color of the RGB LED, and please refer to 1.1.2 RGB LED for more details.

int main(void)
{
    int pir_val;
    //……
    pinMode(pirPin, INPUT);
    while(1){
    pir_val = digitalRead(pirPin);
        if(pir_val== 1){ //if read pir is HIGH level
            ledColorSet(0xff,0xff,0x00);
        }
        else {
        ledColorSet(0x00,0x00,0xff);
        }
    }
    return 0;
}

When PIR detects the human infrared spectrum, RGB LED emits the yellow light; if not, emits the blue light.

Phenomenon Picture

../_images/image215.jpeg