Lesson 34 Tracking Sensor

Introduction

The infrared tracking sensor uses a TRT5000 sensor. The blue LED of TRT5000 is the emission tube and after electrified it emits infrared light invisible to human eye. The black part of the sensor is for receiving; the resistance of the resistor inside changes with the infrared light received.

Components

– 1 * Raspberry Pi

– 1 * Breadboard

– 1 * Network cable (or USB wireless network adapter)

– 1 * Tracking sensor module

– 1 * 3-Pin anti-reverse cable

Experimental Principle

When the infrared transmitter emits rays to a piece of paper, if the rays shine on a white surface, they will be reflected and received by the receiver, and pin SIG will output low level; If the rays encounter black lines, they will be absorbed, thus the receiver gets nothing, and pin SIG will output high level. The schematic diagram:

Experimental Procedures

Step 1: Build the circuit

Raspberry Pi	Tracking Sensor Module
GPIO0	SIG
5V	VCC
GND	GND

For C language users:

Step 2: Change directory

cd /home/pi/SunFounder_SensorKit_for_RPi2/C/34_tracking/

Step 3: Compile

gcc tracking.c -lwiringPi

Step 4: Run

sudo ./a.out

For Python users:

Step 2: Change directory

 cd /home/pi/SunFounder_SensorKit_for_RPi2/Python/

Step 3: Run

sudo python 34_tracking.py

When the tracking sensor encounters black lines, a string “Black Line is detected” will be printed on the screen.

 C Code

#include <wiringPi.h>
#include <stdio.h>

#define TrackSensorPin    0
#define LedPin            1

int main(void)
{
	if(wiringPiSetup() == -1){ //when initialize wiring failed,print messageto screen
		printf("setup wiringPi failed !");
		return 1; 
	}
	
	pinMode(TrackSensorPin, INPUT);
	pinMode(LedPin,  OUTPUT);

	while(1){
		if(digitalRead(TrackSensorPin) == LOW){
			printf("White line is detected\n");
			digitalWrite(LedPin, LOW);     //led on
			delay(100);
			digitalWrite(LedPin, HIGH);    //led off
		}	
		else{
			printf("...Black line is detected\n");
			delay(100);
		}
	}

	return 0;
}

Python Code

#!/usr/bin/env python
import RPi.GPIO as GPIO

TrackPin = 11
LedPin   = 12

def setup():
	GPIO.setmode(GPIO.BOARD)       # Numbers GPIOs by physical location
	GPIO.setup(LedPin, GPIO.OUT)   # Set LedPin's mode is output
	GPIO.setup(TrackPin, GPIO.IN, pull_up_down=GPIO.PUD_UP)
	GPIO.output(LedPin, GPIO.HIGH) # Set LedPin high(+3.3V) to off led

def loop():
	while True:
		if GPIO.input(TrackPin) == GPIO.LOW:
			print 'White line is detected'
			GPIO.output(LedPin, GPIO.LOW)  # led on
		else:
			print '...Black line is detected'
			GPIO.output(LedPin, GPIO.HIGH) # led off

def destroy():
	GPIO.output(LedPin, GPIO.HIGH)     # led off
	GPIO.cleanup()                     # Release resource

if __name__ == '__main__':     # Program start from here
	setup()
	try:
		loop()
	except KeyboardInterrupt:  # When 'Ctrl+C' is pressed, the child program destroy() will be  executed.
		destroy()