Senseur IR

Introduction

IR detectors are little microchips with a photocell that are tuned to listen to infrared light. They are almost always used for remote control detection - every TV and DVD player has one of these in the front to listen for the IR signal from the clicker. Inside the remote control is a matching IR LED, which emits IR pulses to tell the TV to turn on, off or change channels. IR light is not visible to the human eye, which means it takes a little more work to test a setup.

There are a few difference between these and say a Photo-résistance:

• IR detectors are specially filtered for Infrared light, they are not good at detecting visible light. On the other hand, photocells are good at detecting yellow/green visible light, not good at IR light
• IR detectors have a demodulator inside that looks for modulated IR at 38 KHz. Just shining an IR LED wont be detected, it has to be PWM blinking at 38KHz. Photocells do not have any sort of demodulator and can detect any frequency (including DC) within the response speed of the photocell (which is about 1KHz)
• IR detectors are digital out - either they detect 38KHz IR signal and output low (0V) or they do not detect any and output high (5V). Photocells act like resistors, the resistance changes depending on how much light they are exposed to

In this tutorial we will show how to

• Test your IR sensor to make sure its working
• Read raw IR codes into a microcontroller
• Create a camera intervalometer
• Listen for 'commands' from a remote control on your microcontroller

Quelques informations

These stats are for the IR detector in the Adafruit shop (LIEN) also known as PNA4602. Nearly all photocells will have slightly different specifications, although they all pretty much work the same. If there's a datasheet, you'll want to refer to it

• Size: square, 7mm by 8mm detector area
• Price:
• Output: 0V (low) on detection of 38KHz carrier, 5V (high) otherwise
• Sensibilité: 800nm to 1100nm with peak response at 940nm. Frequency range is 35KHz to 41KHz with peak detection at 38KHz
• Power supply: 3-5V DC 3mA
• Fiche technique du PNA4602 (obsolète et plus vendu) ou GP1UX311QS ou TSOP38238 (remplacement, brochage compatible)

Où Acheter

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