IR Object Detection

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IR light from LED

IR light reflected off object

IR LED

IR receiver

Infrared (IR) light leaving an LED reflects off an object. The reflected light travelsback to an IR receiver. The IR receiver “detects” the presence of the object. The object does not need to move to be detected.

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Panasonic PNA4602Msupply voltage: 4.8V – 5.2Vcurrent: 3mA

This sensor detects infrared (IR) light. However, to avoid detecting the IR component of regular sunlight or light from other stray IR sources, the sensor only looks for light coming in at 38 kHz.

IR LED (not your usual LED)outputs 940 nm wavelength light

We write an Arduino sketch to make this LED flash 38,000 times per second so it can be detected by the PNA4602M.

The Parts

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IR Light IR detector is most sensitive around 950 nm or 0.95(10)-6 m

wikipedia.org

Panasonic documentation for PNA4602M

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Install an LED Shield

It is important to install the LED in an enclosure to properly direct the IR light. Your kit includes the black pieces shown. Insert the legs of the LED through the holes in the longer black cylinder, and then install the smaller top piece over the exposed end of the LED.

If you don’t have a shield, a piece of paper can be rolled up and taped around the LED.

Your LED will look like this after shielding.

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220Ω

from digital outputpin on Arduino

LED Circuit IR Receiver Circuit

Be sure to aim your LED and IR detector so that they have a clear view (nothing in the way)

5V

220Ω

to digital inputpin on Arduino

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Arduino Sketchvoid setup() Serial.begin(9600); // allows output to display pinMode(2, OUTPUT); // define digital pin 2 as an output (output to LED) pinMode(3, INPUT); // define digital pin 3 as an input (input from sensor)

void loop() tone(2,38000); // output a LOW HIGH LOW sequence at 38,000 Hz int IR_status= digitalRead(3); // acquire the status of the IR sensor Serial.println(IR_status); // display the status of the IR sensor delay(100); // wait 100ms between sensor queries

nothing is detected by IR sensor

something is detected by IR sensor