IR is a complex piece of technology yet very simple to work with. Unlike LEDs or LASERs, Infrared cannot be seen with the human eye. So in this Instructable, I will demonstrate the basic use of Infrared through 4 different circuits.
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The circuits will not use IR receivers or microcontrollers, instead, they will use a photodiode to detect the IR signal because it is more simple.
The three projects all depend on the IR LED and Photodiode. The IR LED emits infrared radiation in all directions, the photodiode is placed next to it so if an object gets close to it, it will reflect the infrared radiation into the photodiode, the photodiode turns the infrared it absorbed into a signal, the signal then can activate other things. Note the diagram above has a black IR LED and a transparent photodiode, this is not very common as it is usually the other way around, but the following 3 projects use the normal types of IR pairs (IR LED: transparent, Photodiode: Black/dark purple). The colours of the diodes do not matter but just make sure you remember which one is which.
Important things to note (Please read the following):
IR LED: The infrared LED emits IR radiation, we cannot see the radiation because it is a lower frequency than visible light, however, humans can detect infrared as heat (so the IR LED can get a bit hot, that's normal), the radiation is also not harmful.
Photodiode: The photodiode is like an LED but it does not give out light, instead, it is an infrared light sensor (like an LDR but not quite). The photodiode can come in many forms: it usually looks like a black LED but it can also be transparent (in which case don't get it mixed up with other LEDs). The photodiode is connected differently from normal LEDs, instead, Vcc is connected to the cathode rather than the anode of the photodiode.
When purchasing IR LEDs and photodiodes, try to buy them in pairs because sometimes the IR LED does not work with the photodiode.
Before you finish the circuit, make sure the IR LED and Photodiode are placed next to each other.
Once the circuit is complete, test the sensor by hovering an object or your finger about 5cm above the two diodes, then slowly move the object/finger towards the diodes till you touch them both. The generic LED should light up more the closer you get, this is because the object is reflecting more infrared into the photodiode.
If this does not happen, check you have put the photodiode in correctly, check your wire connections, and check your power source, if none of this help, the problem might have occurred between the IR LED and the photodiode. If you have an oscilloscope, try probing the output of the photodiode. If you don't, perhaps try a different IR LED and photodiode pair.
Ensure you do not run the circuit under the sun or very bright light as the EM waves contain a significant amount of IR which can interfere with the circuit.
Remember the two diodes have to be next to each other as the last circuit. To test the circuit, move an object or your hand above the two diodes, this should trigger the alarm. You can also adjust the sensitivity of the photodiode by turning the potentiometer, there will be a point when the alarm will always be on, this is because the photodiode is so sensitive to IR it detects it from the atmosphere around it. It is not possible for me to show the circuit functioning in the picture above but just imagine you can hear the sound of the buzzer.
Do not operate the circuit under the sun or very bright light because that can confuse the photodiode.
To troubleshoot, repeat step 3.
The circuit consists of two pairs of diodes, one turns the output on, the other turns it off. You must first figure out which pair of diodes controls what. Once you do, you can turn the output on by hovering an object over one pair of diodes. The output will stay on even after you have taken your object away from the sensor, the output will only shut off if you hover an object over the other sensor, it will then stay off until you repeat this process.
Again, do not operate under sunlight.
For more flexibility in the circuit, a transistor can be used to drive a relay, which in turn can be used to switch much higher power appliances. This circuit works similar to the first circuit, however, uses a light gate instead.
The photodiode will be conducting when the light gate is completed, which means the transistor will be powered off. When the gate is disrupted, the photodiode will no longer be conducting, thus the transistor switches on and so does the relay.
This circuit can operate from 3.3v to 12v depending on what voltage your relay is rated for. However, from my testing, any voltage below 6v is unreliable as some transistors are unable to provide enough current to power the coil of the relay. R1 should be changed to 220 ohms for 5v to 3.3v. Q1 can be any standard NPN transistor such as 2n, 2n or BC547. Variations of this circuit might use a diode in parallel with the coil for reverse current protection, but in my opinion, that is excessive as the circuit is not connected to sensitive microcontrollers.
IR, or infrared, communication is a common, inexpensive, and easy to use wireless communication technology. IR light is very similar to visible light, except that it has a slightly longer wavelength. This means IR is undetectable to the human eye - perfect for wireless communication. For example, when you hit a button on your TV remote, an IR LED repeatedly turns on and off, 38,000 time a second, to transmit information (like volume or channel control) to an IR photo sensor on your TV.
This is a very simple, clear infrared LED. These devices operate between 940-950nm and work well for generic IR systems inclu&#;
$1.05Use this simple IR receiver for infrared remote control of your next project. With low power consumption and an easy to use p&#;
$2.10This tutorial will first explain the inner workings of common IR communication protocols. Then we will go over two examples that will allow you to transmit and receive IR data using an Arduino. In the first example, we will read incoming IR data from a common remote control using the TSOP382 IR photo sensor. The next example will show you how to transmit data from an IR LED to control a common appliance, for example your home stereo.
All of the gritty signal processing is handled by a great Arduino library written by Ken Shirriff and allows you to easily send and receive IR data. For additional details on how the IR Arduino library works, see Ken Shirriff's blog: A Multi-Protocol Infrared remote Library for the Arduino. Also, the code examples used in this tutorial are found in the examples directory in the library.
Here are some concepts that we will be covering in this tutorial.
IR radiation is simply light that we cannot see, which makes it great for communication. IR sources are all around us. The sun, light bulbs, or any anything with heat is very bright in the IR spectrum. When you use your TV remote, an IR LED is used to transmit information to your TV. So, how does the IR receiver in your TV pick out signals from your remote among all of the ambient IR? The answer is that the IR signal is modulated. Modulating a signal is like assigning a pattern to your data, so that the receiver knows to listen.
A common modulation scheme for IR communication is something called 38kHz modulation. There are very few natural sources that have the regularity of a 38kHz signal, so an IR transmitter sending data at that frequency would stand out among the ambient IR. 38kHz modulated IR data is the most common, but other frequencies can be used.
When you hit a key on your remote, the transmitting IR LED will blink very quickly for a fraction of a second, transmitting encoded data to your appliance.
Each pulse is turned on and off at a frequency of 38kHzIf you were to hook an oscilloscope up to your TV remote's IR LED, you would see a signal similar to the one above. This modulated signal is exactly what the receiving system sees. However, the point of the receiving device is to demodulate the signal and output a binary waveform that can be read by a microcontroller. When you read the OUT pin of the TSOP382 with the wave from above, you will see something like this:
By controlling the spacing between the transmitted modulated signals, the waveform can be read by an input pin on a microcontroller and decoded as a serial bit stream.
Below is conceptual view of how an IR transmitter receiver pair works.
Thanks to SBProjects.com for the gif and excellent IR resource!An Arduino or other microcontroller can be connected to either end of the system to transmit data (left side) or receive data (right side).
For the hardware in this tutorial, you will need the following materials. You may not need everything though depending on what you have. Add it to your cart, read through the guide, and adjust the cart as necessary.
Note: In place of the IR remote control can also use any IR remote that uses 38kHz modulation.You will be setting up two separate circuits both using an Arduino. The first example circuit uses a TSOP382 IR photo sensor to receive and demodulate the IR signal from a common remote control. The second example circuit uses a 950nm IR LED and current limiting resistor to transmit IR codes to a common appliance, for example a home stereo or TV.
Here is the complete setup for connecting to an Arduino:
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Hardware setup for both of the examples.Be sure to connect your LED correctly! The long leg is positive and connects to the resistor, then to the Arduino&#;s output pin. The short leg is negative and is connected to ground (GND).
Also, you cannot see IR LED light with your eyes, since IR radiation is outside of the visible spectrum. However, most cellphone cameras can detect short wave IR and can see the LED faintly glowing.
When the LED is modulating at 38kHz, the LED should appear constantly lit, but dim.Also, pay attention to the polarity of the TSOP382. Refer to the TSOP382 datasheet for the pinout of the sensor.
The current limiting resistor attached to the LED can have values down to 100Ω (40mA) for full power and longest range. If you use a larger value resistor, the LED won't light as bright and your range will suffer. With a 330Ω resistor, you should be able to operate the IR LED across a dimly lit room.
To quickly and easily add IR control to your Arduino, we recommend you download Ken Shirriff's IRremote library. Shirriff has written a library for IR remote. You can obtain this library through the Arduino Library Manager. Search for IRremote by shirriff and you should be able to install the latest version. If you prefer downloading the libraries manually you can grab them from the GitHub repository:
Warning: Make sure the folder name that you copy into your "libraries" folder is named "IRremote". Use of the ` - ` in the directory name can lead to errors in compiling the code.The IRremote library is a powerful tool for adding IR to your project. Whether you want to send IR codes out to an appliance, or transmit IR codes from a remote to your Arduino (or both!). We'll go over some of the simple stuff you can do with the library. For more help using it, check out Ken Shirriff's blog.
IR remote controls are as ubiquitous as their appliance counterparts. What if you could put all of those old remote controls to use in your next project? This example will show you how to read IR remote codes from any IR remote using the TSOP382 IR receiver and an Arduino. Once you can receive codes from individual button presses, your remote control and Arduino become a general purpose, short range, communication interface!
In this example, all you need is the TSOP382 IR receiver connected to an Arduino and a common remote control. The IR LED and button can stay connected, but you will not use it until the next example.Assuming that you have the IR library, go to your Arduino project directory: Arduino/libraries/IRremote/examples/IRrecvDemo and open the IRrecvDemo.ino. Upload the sketch to your Arduino.
The sketch will automatically decode the type of remote you are using and identify which button on your remote is pressed. Open the serial port in the Arduino IDE at bps and hit different buttons on your remote.
Terminal window displaying random button presses on my remote. Different buttons show different codes.When specific buttons are pressed, you can use the incoming values to do something else in your code, for example turn on and off a motor or LED.
The results from each button press can be found by calling the value() method:
language:c
results.value
You can print the values to the terminal window:
language:c
Serial.println(results.value, HEX); //prints the hex value a a button press
Or you might need read the values to run a conditional statement:
language:c
if(irrecv.decode(&results)) //this checks to see if a code has been received
{
if(results.value == 0xC284) //if the button press equals the hex value 0xC284
{
//do something useful here
}
irrecv.resume(); //receive the next value
}
In this example, your Arduino and an IR LED imitate an IR remote to control an appliance (TV, stereo, etc.). In order to control your appliance with the LED, you need to know what type of IR protocol your appliance uses. The easiest way to find this out is to have the remote that comes with the appliance. This example receives a remote key press with the TSOP382 IR receiver, copies the data, then sends it out of the IR LED.
This example uses both the LED and TSOP382.Assuming that you have the IRremote library, go to your Arduino project directory: Arduino/libraries/IRremote/examples/IRrecord and open the IRrecord.ino. Upload the sketch to your Arduino.
After you have loaded the sketch, open the Arduino serial monitor to bps. Point your remote directly at the TSOP382 and hit a button. You should see specific codes in the terminal window, corresponding to the button you hit on the remote.
Now if you point the LED at your appliance and hit the push button that is connected to your Arduino, the code for the button press on your remote will be sent. Once you know which codes correspond to each button, you can create your own remote with the Arduino and IR LED.
For example, the transmitting IR example circuit received an unknown code when the volume up button on my Panasonic remote was hit. The data bytes on the second line are the raw codes displayed as mark and space timings for the volume up command.
If you received an unknown code and want to send it, use this line in your Arduino sketch:
language:c
irsend.sendRaw(rawCodes, codeLen, 38);
If you don&#;t have the appliance&#;s remote or if you are lucky enough to have a remote that uses a common protocol, then you can try the pre-loaded manufacturer codes from the IRSendDemo.ino example in the IRremote library.
For example, if you have a Sony TV and want the LED to turn your TV on/off, you can use this piece of code:
language:c
for (int i = 0; i < 3; i++)
{
irsend.sendSony(0xa90, 12); // Sony TV power code
delay(40);
}
Different appliance manufacturers use different protocols to send commands. This is why you have to define the manufacturer of the appliance to use this library. Also, note that the Sony command needs to be sent three times using a for() loop. Every protocol will have its own intricacies. A good reference for un-official commands to common IR protocols can be found on San Bergmans' website:
There are a few common protocols the IR Arduino library supports. They are: NEC, Sony SIRC, Philips RC5, Philips RC6, and raw formats. Here are the methods you can use in your Arduino code for different manufacturers:
language:c
void sendNEC(unsigned long data, int nbits);
void sendSony(unsigned long data, int nbits);
void sendRC5(unsigned long data, int nbits);
void sendRC6(unsigned long data, int nbits);
void sendDISH(unsigned long data, int nbits);
void sendSharp(unsigned long data, int nbits);
void sendPanasonic(unsigned int address, unsigned long data);
void sendJVC(unsigned long data, int nbits, int repeat);
void sendRaw(unsigned int buf[], int len, int hz);
You will need to fill in the data and nbits fields with a information specific to the protocol you are using. More information on how use this feature can be found in the IR Arduino library blog post (see the "Details of the sending library" section).
Infrared LEDs are awesome. Along with an IR receiver they can be used for remote control and even basic remote data communica&#;
RetiredIf you're looking for more documents and resources related to the IR LED or receiver, check out some of these links:
If you're looking for general information on infrared communication SparkFun Engineer Chris Taylor's IR Project video:
ReplaceMeOpen
ReplaceMeClose
And there's also Jeff Branson, starring in an IR Communication video tutorial using our IR Emitter/Detector Pair:
Side-looking Infrared Emitters and IR Detectors. These simple devices operate at 940nm and work well for generic IR systems i&#;
RetiredNow you should be prepared to create an IR communication system of your own. What are you going to control with this extravisible, modulated light source? Need some inspiration? Check out some of these tutorials:
Or check out some of these blog posts for ideas:
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