Unknown protocol
If your protocol seems not to be supported by this library, you may try the IRMP library.
Sending IR codes
If you have a device at hand which can generate the IR codes you want to work with (aka IR remote), it is recommended to receive the codes with the ReceiveDemo example, which will tell you on the serial output how to send them.
Protocol=LG Address=0x2 Command=0x3434 Raw-Data=0x23434E 28 bits MSB first Send with: IrSender.sendLG(0x2, 0x3434,
);
You will discover that the address is a constant and the commands sometimes are sensibly grouped.If you are uncertain about the numbers of repeats to use for sending, 3 is a good starting point. If this works, you can check lower values afterwards.
The codes found in the irdb database specify a device, a subdevice and a function. Most of the times, device and subdevice can be taken as upper and lower byte of the address parameter and function is the command parameter for the new structured functions with address, command and repeat-count parameters like e.g.
IrSender.sendNEC((device << 8) | subdevice, 0x19, 2)
.An exact mapping can be found in the IRP definition files for IR protocols. “D” and “S” denotes device and subdevice and “F” denotes the function.
All sending functions support the sending of repeats if sensible.
Repeat frames are sent at a fixed period determined by the protocol. e.g. 110 ms from start to start for NEC.Keep in mind, that there is no delay after the last sent mark. If you handle the sending of repeat frames by your own, you must insert sensible delays before the repeat frames to enable correct decoding.
The old send*Raw() functions for sending like e.g.
IrSender.sendNECRaw(0xE61957A8,2)
are kept for backward compatibility to (old) tutorials and unsupported as well as error prone.
How to Connect an IR Receiver to the Arduino
There are several different types of IR receivers, some are stand-alone, and some are mounted on a breakout board. Check the datasheet for your particular IR receiver since the pins might be arranged differently than the HX1838 IR receiver and remote set I am using here. However, all IR receivers will have three pins: signal, ground, and Vcc.
Lets get started with the hardware connections. The pin layout on most breakout boards looks like this:
The pinout of most stand-alone diodes is like this:
To connect a breakout board mounted IR receiver, hook it up to the Arduino like this:
To connect a stand-alone receiver diode, wire it like this:
Protocol=UNKNOWN
If you see something like
Protocol=UNKNOWN Hash=0x13BD886C 35 bits received
as output of e.g. the ReceiveDemo example, you either have a problem with decoding a protocol, or an unsupported protocol.
- If you have an odd number of bits received, your receiver circuit probably has problems. Maybe because the IR signal is too weak.
-
If you see timings like
+ 600,- 600 + 550,- 150 + 200,- 100 + 750,- 550
then one 450 µs space was split into two 150 and 100 µs spaces with a spike / error signal of 200 µs between. Maybe because of a defective receiver or a weak signal in conjunction with another light emitting source nearby. -
If you see timings like
+ 500,- 550 + 450,- 550 + 500,- 500 + 500,-1550
, then marks are generally shorter than spaces and therefore
MARK_EXCESS_MICROS
(specified in your ino file) should be negative to compensate for this at decoding. -
If you see
Protocol=UNKNOWN Hash=0x0 1 bits received
it may be that the space after the initial mark is longer than
RECORD_GAP_MICROS
. This was observed for some LG air conditioner protocols. Try again with a line e.g.
#define RECORD_GAP_MICROS 12000
before the line
#include
in your .ino file. -
To see more info supporting you to find the reason for your UNKNOWN protocol, you must enable the line
//#define DEBUG
in IRremoteInt.h.
Minimal CPU clock frequency
For receiving, the minimal CPU clock frequency is 4 MHz, since the 50 µs timer ISR (Interrupt Service Routine) takes around 12 µs on a 16 MHz ATmega.The TinyReceiver, which reqires no polling, runs with 1 MHz.For sending, the default software generated PWM has problems on AVR running with 8 MHz. The PWM frequency is around 30 instead of 38 kHz and RC6 is not reliable. You can switch to timer PWM generation by
#define SEND_PWM_BY_TIMER
.
How to convert old MSB first 32 bit IR data codes to new LSB first 32 bit IR data codes
For the new decoders for NEC, Panasonic, Sony, Samsung and JVC, the result
IrReceiver.decodedIRData.decodedRawData
is now LSB-first, as the definition of these protocols suggests!To convert one into the other, you must reverse the byte/nibble positions and then reverse all bit positions of each byte/nibble or write it as one binary string and reverse/mirror it.Example:
0xCB 34 01 02
0x20 10 43 BC
after nibble reverse
0x40 80 2C D3
after bit reverse of each nibble
Nibble reverse map:
0->0 1->8 2->4 3->C 4->2 5->A 6->6 7->E 8->1 9->9 A->5 B->D C->3 D->B E->7 F->F
0xCB340102
is binary
1100 1011 0011 0100 0000 0001 0000 0010
.
0x40802CD3
is binary
0100 0000 1000 0000 0010 1100 1101 0011
.If you read the first binary sequence backwards (right to left), you get the second sequence. You may use
bitreverseOneByte()
or
bitreverse32Bit()
for this.
Errors with using the 4.x versions for old tutorials
If you suffer from errors with old tutorial code including
IRremote.h
instead of
IRremote.hpp
, just try to rollback to Version 2.4.0.Most likely your code will run and you will not miss the new features…
Print Keys to an LCD
Instead of printing the key values to the serial monitor, you can also display the information on an LCD. Check out our article on setting up and programming an LCD on the Arduino for more information on programming the LCD, but the basic setup looks like this:
The resistor sets the LCD’s backlight brightness. It can be anything from 200 ohms to about 2K ohms. The potentiometer sets the character contrast. I normally use a 10K ohm potentiometer for this one.
Once everything is connected, upload this code to the Arduino:
#include
#includeconst int RECV_PIN = 7; LiquidCrystal lcd(12, 11, 5, 4, 3, 2); IRrecv irrecv(RECV_PIN); decode_results results; unsigned long key_value = 0; void setup(){ Serial.begin(9600); irrecv.enableIRIn(); irrecv.blink13(true); lcd.begin(16, 2); } void loop(){ if (irrecv.decode(&results)){ if (results.value == 0XFFFFFFFF) results.value = key_value; lcd.setCursor(0, 0); lcd.clear(); switch(results.value){ case 0xFFA25D: lcd.print("CH-"); break; case 0xFF629D: lcd.print("CH"); break; case 0xFFE21D: lcd.print("CH+"); break; case 0xFF22DD: lcd.print("|<<"); break; case 0xFF02FD: lcd.print(">>|"); break ; case 0xFFC23D: lcd.print(">|"); break ; case 0xFFE01F: lcd.print("-"); break ; case 0xFFA857: lcd.print("+"); break ; case 0xFF906F: lcd.print("EQ"); break ; case 0xFF6897: lcd.print("0"); break ; case 0xFF9867: lcd.print("100+"); break ; case 0xFFB04F: lcd.print("200+"); break ; case 0xFF30CF: lcd.print("1"); break ; case 0xFF18E7: lcd.print("2"); break ; case 0xFF7A85: lcd.print("3"); break ; case 0xFF10EF: lcd.print("4"); break ; case 0xFF38C7: lcd.print("5"); break ; case 0xFF5AA5: lcd.print("6"); break ; case 0xFF42BD: lcd.print("7"); break ; case 0xFF4AB5: lcd.print("8"); break ; case 0xFF52AD: lcd.print("9"); break ; } key_value = results.value; irrecv.resume(); } }
Again, if the hex codes don’t match the codes output by your remote, just replace them for each character where it says
case 0xXXXXXXXX;
.
Programming the IR Receiver
Once you have the receiver connected, we can install the Arduino library and start programming. In the examples below, I’ll show you how to find the codes sent by your remote, how to find the IR protocol used by your remote, how to print key presses to the serial monitor or an LCD, and finally, how to control the Arduino’s output pins with a remote.
Install the IRremote Library
We’ll be using the IRremote library for all of the code examples below. You can download a ZIP file of the library from here.
To install the library from the ZIP file, open up the Arduino IDE, then go to Sketch > Include Library > Add .ZIP Library, then select the IRremote ZIP file that you downloaded from the link above.
Find the Codes for Your Remote
To find the key codes for your remote control, upload this code to your Arduino and open the serial monitor:
#include
const int RECV_PIN = 7; IRrecv irrecv(RECV_PIN); decode_results results; void setup(){ Serial.begin(9600); irrecv.enableIRIn(); irrecv.blink13(true); } void loop(){ if (irrecv.decode(&results)){ Serial.println(results.value, HEX); irrecv.resume(); } }
Now press each key on your remote and record the hexadecimal code printed for each key press.
Using the program above, I derived a table of keys and their corresponding codes from the remote that came with my HX1838 IR receiver and remote set. Note that you will receive a 0XFFFFFFFF code when you press a key continuously.
Key | Code |
CH- | 0xFFA25D |
CH | 0xFF629D |
CH+ | 0xFFE21D |
<< | 0xFF22DD |
>> | 0xFF02FD |
>|| | 0xFFC23D |
0xFFE01F | |
0xFFA857 | |
EQ | 0xFF906F |
100+ | 0xFF9867 |
200+ | 0xFFB04F |
0XFF6897 | |
0xFF30CF | |
0xFF18E7 | |
0xFF7A85 | |
0xFF10EF | |
0xFF38C7 | |
0xFF5AA5 | |
0xFF42BD | |
0xFF4AB5 | |
0xFF52AD |
Find the Protocol Used by Your Remote
Knowing which protocol your remote uses can be useful if you want to work on some more advanced projects. Or you might just be curious. The program below will identify the protocol used by your remote. It should even work on most of the remote controls around your house.
#include
const int RECV_PIN = 7; IRrecv irrecv(RECV_PIN); decode_results results; void setup(){ Serial.begin(9600); irrecv.enableIRIn(); irrecv.blink13(true); } void loop(){ if (irrecv.decode(&results)){ Serial.println(results.value, HEX); switch (results.decode_type){ case NEC: Serial.println("NEC"); break ; case SONY: Serial.println("SONY"); break ; case RC5: Serial.println("RC5"); break ; case RC6: Serial.println("RC6"); break ; case DISH: Serial.println("DISH"); break ; case SHARP: Serial.println("SHARP"); break ; case JVC: Serial.println("JVC"); break ; case SANYO: Serial.println("SANYO"); break ; case MITSUBISHI: Serial.println("MITSUBISHI"); break ; case SAMSUNG: Serial.println("SAMSUNG"); break ; case LG: Serial.println("LG"); break ; case WHYNTER: Serial.println("WHYNTER"); break ; case AIWA_RC_T501: Serial.println("AIWA_RC_T501"); break ; case PANASONIC: Serial.println("PANASONIC"); break ; case DENON: Serial.println("DENON"); break ; default: case UNKNOWN: Serial.println("UNKNOWN"); break ; } irrecv.resume(); } }
Print Keys to the Serial Monitor
I extended the code above to print the key value instead of the hexadecimal code:
#include
const int RECV_PIN = 7; IRrecv irrecv(RECV_PIN); decode_results results; unsigned long key_value = 0; void setup(){ Serial.begin(9600); irrecv.enableIRIn(); irrecv.blink13(true); } void loop(){ if (irrecv.decode(&results)){ if (results.value == 0XFFFFFFFF) results.value = key_value; switch(results.value){ case 0xFFA25D: Serial.println("CH-"); break; case 0xFF629D: Serial.println("CH"); break; case 0xFFE21D: Serial.println("CH+"); break; case 0xFF22DD: Serial.println("|<<"); break; case 0xFF02FD: Serial.println(">>|"); break ; case 0xFFC23D: Serial.println(">|"); break ; case 0xFFE01F: Serial.println("-"); break ; case 0xFFA857: Serial.println("+"); break ; case 0xFF906F: Serial.println("EQ"); break ; case 0xFF6897: Serial.println("0"); break ; case 0xFF9867: Serial.println("100+"); break ; case 0xFFB04F: Serial.println("200+"); break ; case 0xFF30CF: Serial.println("1"); break ; case 0xFF18E7: Serial.println("2"); break ; case 0xFF7A85: Serial.println("3"); break ; case 0xFF10EF: Serial.println("4"); break ; case 0xFF38C7: Serial.println("5"); break ; case 0xFF5AA5: Serial.println("6"); break ; case 0xFF42BD: Serial.println("7"); break ; case 0xFF4AB5: Serial.println("8"); break ; case 0xFF52AD: Serial.println("9"); break ; } key_value = results.value; irrecv.resume(); } }
If your remote sends different codes than the ones in the table above, just replace the hex code in each line where it says:
case 0xFFA25D: Serial.println(“CH-“);
In these lines, when the hex code
0xFFA25D
is received, the Arduino prints “CH-“.
How the Code Works
For any IR communication using the IRremote library, first we need to create an object called
irrecv
and specify the pin number where the IR receiver is connected (line 3). This object will take care of the protocol and processing of the information from the receiver.
The next step is to create an object called
results
, from the
decode_results
class, which will be used by the
irrecv
object to share the decoded information with our application (line 5).
In the
void setup()
block, first we configure the serial monitor baud rate. Next we start the IR receiver by calling the
IRrecv
member function
enableIRIn()
(line 10).
The
irrecv.blink13(true)
function on line 11 will blink the Arduino’s on board LED every time the receiver gets a signal from the remote control, which is useful for debugging.
In the
void loop()
block, the function
irrecv.decode
will return true if a code is received and the program will execute the code in the if statement. The received code is stored in
results.value
. Then I used a switch to handle each IR code and print the corresponding key value.
Before the switch block starts there is a conditional block:
if (results.value == 0XFFFFFFFF) results.value = key_value;
If we receive 0XFFFFFFFF from the remote, it means a repetition of the previous key. So in order to handle the repeat key pattern, I am storing the hex code in a global variable
key_value
every time a code is received:
key_value = results.value;
When you receive a repeat pattern, then the previously stored value is used as the current key press.
At the end of the
void loop()
section, we call
irrecv.resume()
to reset the receiver and prepare it to receive the next code.
Install an Arduino library for the IR remote controller
Be reassured: you won’t have to write hundreds of lines of code to be able to decode the data you get from the IR receiver. Someone already did that for you. All you need to do is to install an Arduino library and use it.
To do that, open the Arduino IDE. Go to Tools > Manage Libraries.
You will get a new window, where you will see many available libraries that you can install. In the search bar, type “irremote”.
You will find this IRremote library (by shirrif, z3t0, ArminJo).
Select the latest version (whatever version is fine, it doesn’t have to be exactly the same as the one you see on the screenshot). The important thing is to have a version starting by at least 3. Don’t use version 2.
Click on “Install” and wait a few seconds. Then you can close the window, and restart the Arduino IDE.
The IRremote library is now installed and ready to be used!
(if you want to download a specific library version not available from the Arduino IDE, you can also directly get the library from GitHub)
Incompatibilities to other libraries and Arduino commands like tone() and analogWrite()
If you use a library which requires the same timer as IRremote, you have a problem, since the timer resource cannot be shared simultaneously by both libraries.
Change timer
The best approach is to change the timer used for IRremote, which can be accomplished by specifying the timer before
#include
.The timer specifications available for your board can be found in private/IRTimer.hpp.
// Arduino Mega #elif defined(__AVR_ATmega1280__) || defined(__AVR_ATmega2560__) # if !defined(IR_USE_AVR_TIMER1) && !defined(IR_USE_AVR_TIMER2) && !defined(IR_USE_AVR_TIMER3) && !defined(IR_USE_AVR_TIMER4) && !defined(IR_USE_AVR_TIMER5) //#define IR_USE_AVR_TIMER1 // send pin = pin 11 #define IR_USE_AVR_TIMER2 // send pin = pin 9 //#define IR_USE_AVR_TIMER3 // send pin = pin 5 //#define IR_USE_AVR_TIMER4 // send pin = pin 6 //#define IR_USE_AVR_TIMER5 // send pin = pin 46 # endif
Here you see the Arduino Mega board and the available specifications are
IR_USE_AVR_TIMER[1,2,3,4,5]
.You just have to include a line e.g.
#define IR_USE_AVR_TIMER3
before
#include
to enable timer 3.
But be aware that the new timer in turn might be incompatible with other libraries or commands.For other boards/platforms you must look for the appropriate section guarded by e.g.
#elif defined(ESP32)
.
Stop and start timer
Another approach can be to share the timer sequentially if their functionality is used only for a short period of time like for the Arduino tone() command.
An example can be seen here, where the timer settings for IR receive are restored after the tone has stopped.
For this we must call
IrReceiver.start()
or better
IrReceiver.start(microsecondsOfToneDuration)
.This only works since each call to
tone()
completely initializes the timer 2 used by the
tone()
command.
Receive controls from your remote control!
Written By: Marcus Schappi
Difficulty
Easy
Steps
11
An IR receiver uses infrared communication. Infrared light, unlike visible light, has a slightly longer wavelength and so is undetectable to the human eye. But it is detectable by a TV which listens for IR signals.
In this guide, you will learn how to capture button presses on a remote with the 100% compatible Arduino development board, the Little Bird Uno R3 and an Arduino compatible IR receiver module. Have a try with a few different remote controls you have around the house!
After completing this guide, you will understand the basics involved and can use an IR receiver in your very own Arduino projects!
Connect Digital Pin 11 to the Signal Pin of the IR Receiver.
Connect 5V to the 5V (middle) Pin of the IR Receiver.
Connect Ground to the Ground Pin of the IR Receiver.
Insert the LED into the breadboard with the Cathode (shorter leg) on the left hand side.
Insert a 220 Ohm Resistor into the Breadboard with one leg in line with the LED’s anode (longer leg).
#include
#include
int RECV_PIN = 11; //define input pin on Arduino IRrecv irrecv(RECV_PIN); decode_results results; void setup() { Serial.begin(9600); irrecv.enableIRIn(); // Start the receiver pinMode(LED_BUILTIN, OUTPUT); } void loop() { if (irrecv.decode( & results)) { String hex = String(results.value, HEX); Serial.print(“Hexadecimal Code: “); Serial.println(hex); if(hex == “ff18e7”){ digitalWrite(LED_BUILTIN, HIGH); // turn the LED on (HIGH is the voltage level) } if(hex == “ff4ab5”){ digitalWrite(LED_BUILTIN, LOW); // turn the LED off by making the voltage LOW } irrecv.resume(); // Receive the next value } }
Copy this code and open it in your Arduino IDE.
This code won’t work without the IRremote Library (we’ll install that next).
Open the Arduino Library Manager by clicking on Sketch → Include Libraries → Manage Libraries.
Search for the IRremote Library and install the latest version.
In this tutorial I will show you how to setup and use an IR (InfraRed) remote controller with Arduino.
You will learn how to map each button of the controller to a specific action, so you can make your Arduino programs more dynamic.
After reading this post you will be able to fully integrate any IR remote controller to any of your Arduino projects.
Table of Contents
decodedIRData structure
struct IRData { decode_type_t protocol; // UNKNOWN, NEC, SONY, RC5, PULSE_DISTANCE, … uint16_t address; // Decoded address uint16_t command; // Decoded command uint16_t extra; // Used for Kaseikyo unknown vendor ID. Ticks used for decoding Distance protocol. uint16_t numberOfBits; // Number of bits received for data (address + command + parity) – to determine protocol length if different length are possible. uint8_t flags; // IRDATA_FLAGS_IS_REPEAT, IRDATA_FLAGS_WAS_OVERFLOW etc. See IRDATA_FLAGS_* definitions IRRawDataType decodedRawData; // Up to 32 (64 bit for 32 bit CPU architectures) bit decoded raw data, used for sendRaw functions. uint32_t decodedRawDataArray[RAW_DATA_ARRAY_SIZE]; // 32 bit decoded raw data, to be used for send function. irparams_struct *rawDataPtr; // Pointer of the raw timing data to be decoded. Mainly the data buffer filled by receiving ISR. };
Flags
This is the list of flags contained in the flags field.Check it with e.g.
if(IrReceiver.decodedIRData.flags & IRDATA_FLAGS_IS_REPEAT)
.
Flag name | Description |
IRDATA_FLAGS_IS_REPEAT | The gap between the preceding frame is as smaller than the maximum gap expected for a repeat. !!!We do not check for changed command or address, because it is almost not possible to press 2 different buttons on the remote within around 100 ms!!! |
IRDATA_FLAGS_IS_AUTO_REPEAT | The current repeat frame is a repeat, that is always sent after a regular frame and cannot be avoided. Only specified for protocols DENON, and LEGO. |
IRDATA_FLAGS_PARITY_FAILED | The current (autorepeat) frame violated parity check. |
IRDATA_FLAGS_TOGGLE_BIT | Is set if RC5 or RC6 toggle bit is set. |
IRDATA_FLAGS_EXTRA_INFO | There is extra info not contained in address and data (e.g. Kaseikyo unknown vendor ID, or in decodedRawDataArray). |
IRDATA_FLAGS_WAS_OVERFLOW | irparams.rawlen is set to 0 in this case to avoid endless OverflowFlag. |
IRDATA_FLAGS_IS_MSB_FIRST | This value is mainly determined by the (known) protocol. |
To access the RAW data, use:
auto myRawdata= IrReceiver.decodedIRData.decodedRawData;
The definitions for the
IrReceiver.decodedIRData.flags
are described here.
Print all fields:
IrReceiver.printIRResultShort(&Serial);
Print the raw timing data received:
IrReceiver.printIRResultRawFormatted(&Serial, true);`
The raw data depends on the internal state of the Arduino timer in relation to the received signal and might therefore be slightly different each time. (resolution problem). The decoded values are the interpreted ones which are tolerant to such slight differences!
Print how to send the received data:
IrReceiver.printIRSendUsage(&Serial);
Introduction: Arduino Infrared Remote Tutorial
It is really easy to control an Arduino using an infrared remote. There is one particular remote that is available from multiple sources and is really quite cheap, they look and operate in a very similar way.NEOMART Raspberry Pi HX1838 Infrared Remote Control Ir Receiver Module DIY Kit. AmazonKootek Raspberry Pi Infrared Remote Control Ir Receiver Module DIY Kit. AmazonKIT,IR REMOTE,IR RECIVER,ARDUI,COMPATIBLE JamecoThe problem is that documentation seems to be scarce for these particular remotes. Here is how I figured out how to use them.
How To Program For IR Remote Controller
- Include the library:
- Declare a DIYables_IRcontroller_17 or DIYables_IRcontroller_21 object corresponds with 17-key or 21-key IR remote controllers:
- Initialize the IR Controller.
- In the loop, check if a key is pressed or not. If yes, get the key
- Once you have detected a key press, you can perform specific actions based on each key.
Ambiguous protocols
NEC, Extended NEC, ONKYO
The NEC protocol is defined as 8 bit address and 8 bit command. But the physical address and data fields are each 16 bit wide.
The additional 8 bits are used to send the inverted address or command for parity checking.The extended NEC protocol uses the additional 8 parity bit of address for a 16 bit address, thus disabling the parity check for address.The ONKYO protocol in turn uses the additional 8 parity bit of address and command for a 16 bit address and command.
The decoder reduces the 16 bit values to 8 bit ones if the parity is correct. If the parity is not correct, it assumes no parity error, but takes the values as 16 bit values without parity assuming extended NEC or extended NEC protocol protocol.
But now we have a problem when we want to receive e.g. the 16 bit address 0x00FF or 0x32CD! The decoder interprets this as a NEC 8 bit address 0x00 / 0x32 with correct parity of 0xFF / 0xCD and reduces it to 0x00 / 0x32.
One way to handle this, is to force the library to always use the ONKYO protocol interpretation by using
#define DECODE_ONKYO
.
Another way is to check if
IrReceiver.decodedIRData.protocol
is NEC and not ONKYO and to revert the parity reducing manually.
NEC, NEC2
On a long press, the NEC protocol does not repeat its frame, it sends a special short repeat frame. This enables an easy distinction between long presses and repeated presses and saves a bit of battery energy. This behavior is quite unique for NEC and its derived protocols like LG.
So there are of course also remote control systems, which uses the NEC protocol but on a long press just repeat the first frame instead of sending the special short repeat frame. We named this the NEC2 protocol and it is sent with
sendNEC2()
.But be careful, the NEC2 protocol can only be detected by the NEC library decoder after the first frame and if you do a long press!
Application example: blink some LEDs with the IR remote controller
In this application, what we want to do is simply to toggle a red LED when we press on button 2, and toggle a green LED when we press on button play/pause.
Circuit
Let’s build this circuit.
We use the same circuit as before, and add 2 LEDs:
- For each LED, plug the shorter leg to GND.
- plug the longer leg to a 220Ohm resistor.
- Connect the other leg of the resistor to pin 12 (red LED) and pin 11 (green LED).
Code
Here is the code for the application.
#include
#define IR_RECEIVE_PIN 8 #define IR_BUTTON_2 24 #define IR_BUTTON_PLAY_PAUSE 64 #define RED_LED_PIN 12 #define GREEN_LED_PIN 11 byte redLedState = LOW; byte greenLedState = LOW; void setup() { IrReceiver.begin(IR_RECEIVE_PIN); pinMode(RED_LED_PIN, OUTPUT); pinMode(GREEN_LED_PIN, OUTPUT); } void loop() { if (IrReceiver.decode()) { IrReceiver.resume(); int command = IrReceiver.decodedIRData.command; switch (command) { case IR_BUTTON_2: { redLedState = (redLedState == LOW) ? HIGH : LOW; digitalWrite(RED_LED_PIN, redLedState); break; } case IR_BUTTON_PLAY_PAUSE: { greenLedState = (greenLedState == LOW) ? HIGH: LOW; digitalWrite(GREEN_LED_PIN, greenLedState); break; } default: { // do nothing } } } }
If you run this, and press on button “play/pause”, you will see the green LED powered on. If you press again, the green LED will be powered off. Etc. The same applies for the red LED when you press on the button “2”.
And let’s now break the code down.
#include
#define IR_RECEIVE_PIN 8 #define IR_BUTTON_2 24 #define IR_BUTTON_PLAY_PAUSE 64
As we have already mapped the buttons, we reuse the same defines we previously wrote. Here we just need buttons “2” and “play/pause” so I’ve only included the numbers for those 2 buttons.
#define RED_LED_PIN 12 #define GREEN_LED_PIN 11 byte redLedState = LOW; byte greenLedState = LOW;
We set some defines for the LED’s pin numbers. We also keep the state of both LEDs in a global variable, so we will be able to retrieve and toggle this state.
void setup() { IrReceiver.begin(IR_RECEIVE_PIN); pinMode(RED_LED_PIN, OUTPUT); pinMode(GREEN_LED_PIN, OUTPUT); }
In the setup() we initialize the IR receiver component, and the 2 LEDs with pinMode() function and OUTPUT mode.
void loop() { if (IrReceiver.decode()) { IrReceiver.resume(); int command = IrReceiver.decodedIRData.command; switch (command) {
This is exactly the same as what we did before. We check if there is some data to read from the IR receiver. If yes, we get the data, we resume the sensor, and we check which button was pressed with a switch structure.
case IR_BUTTON_2: { redLedState = (redLedState == LOW) ? HIGH : LOW; digitalWrite(RED_LED_PIN, redLedState); break; }
When the button “2” is pressed, we toggle the LED state with a one-liner: (redLedState == LOW) will be evaluated to true or false. If it’s true (variable is LOW), we set the variable to HIGH, and if it’s false (variable is HIGH), we set the variable to LOW.
After that we apply the new state to the LED with digitalWrite().
That’s it! If you know how to toggle an LED, and how to get data from an IR receiver, combining the 2 together is really easy.
case IR_BUTTON_PLAY_PAUSE: { greenLedState = (greenLedState == LOW) ? HIGH: LOW; digitalWrite(GREEN_LED_PIN, greenLedState); break; }
We do the same thing for the green LED, when we press on the “play/pause” button.
default: { // do nothing } } } }
And finally we have the switch default, which we don’t use here.
About IR Remote Control
An IR control system includes two components:
- IR remote controller
- IR receiver
An IR kit usually includes two above components.
IR remote controller
The IR remote controller is a handheld device that emits infrared signals. The IR remote controller consists of a keypad with various buttons:
- Each button on the remote controller corresponds to a specific function or command.
- When a button is pressed, the remote emits an infrared signal that carries a unique code or pattern associated with the pressed button.
- These infrared signals are not visible to the human eye as they are in the infrared spectrum.
IR Receiver
The IR receiver module is a sensor that detects and receives the infrared signals emitted by the remote controller.
The infrared receiver detects the incoming infrared signals and converts them into the code (command) representing the button pressed on the remote controller.
The IR Receiver can be a sensor or a module. You can use the following choices:
- IR Receiver Module only
- IR Receiver Sensor only
- IR Receiver Sensor + Adapter
IR Receiver Pinout
IR receiver module or sensor has three pins:
- VCC pin: Connect this pin to the 3.3V or 5V pin of the Arduino or external power source.
- GND pin: Connect this pin to GND pin of the Arduino or external power source..
- OUT (Output) pin: This pin is the output pin of the IR receiver module. Connected to a digital input pin on the Arduino.
How It Works
When user presses a button on the IR remote controller
- The IR remote controller encodes the command corresponding to the button to the infrared signal via a specific protocol
- The IR remote controller emits the encoded infrared signal
- The IR receiver receives the encoded infrared signal
- The IR receiver decoded the encoded infrared signal in to the command
- The Arduino reads the command from the IR receiver
- The Arduino maps the command to the key pressed
It seems to be complicated but don’t worry. With the help of DIYables_IRcontroller library, it is a piece of cake.
Sơ đồ nguyên lý
Các linh kiện cần thiết cho dự án
Tên linh kiện | Số lượng |
Arduino Uno R3 | |
Dây cắm | |
Breadboard | |
IR Receiver | |
LED 5mm | |
Trở 220R | |
IR Remote |
Why do we use 30% duty cycle for sending
We do it according to the statement in the Vishay datasheet:
- Carrier duty cycle 50 %, peak current of emitter IF = 200 mA, the resulting transmission distance is 25 m.
- Carrier duty cycle 10 %, peak current of emitter IF = 800 mA, the resulting transmission distance is 29 m. – Factor 1.16 The reason is, that it is not the pure energy of the fundamental which is responsible for the receiver to detect a signal. Due to automatic gain control and other bias effects, high intensity of the 38 kHz pulse counts more than medium intensity (e.g. 50% duty cycle) at the same total energy.
How we decode signals
The IR signal is sampled at a 50 µs interval. For a constant 525 µs pulse or pause we therefore get 10 or 11 samples, each with 50% probability.And believe me, if you send a 525 µs signal, your receiver will output something between around 400 and 700 µs!Therefore we decode by default with a +/- 25% margin using the formulas here.E.g. for the NEC protocol with its 560 µs unit length, we have TICKS_LOW = 8.358 and TICKS_HIGH = 15.0. This means, we accept any value between 8 ticks / 400 µs and 15 ticks / 750 µs (inclusive) as a mark or as a zero space. For a one space we have TICKS_LOW = 25.07 and TICKS_HIGH = 45.0.And since the receivers generated marks are longer or shorter than the spaces, we have introduced the
MARK_EXCESS_MICROS
macro
to compensate for this receiver (and signal strength as well as ambient light dependent 😞 ) specific deviation.Welcome to the world of real world signal processing.
NEC encoding diagrams
Created with sigrok PulseView with IR_NEC decoder by DjordjeMandic.8 bit address NEC code
16 bit address NEC code
Quick comparison of 5 Arduino IR receiving libraries
This is a short comparison and may not be complete or correct.
I created this comparison matrix for myself in order to choose a small IR lib for my project and to have a quick overview, when to choose which library.It is dated from 24.06.2022 and updated 10/2023. If you have complains about the data or request for extensions, please send a PM or open a discussion.
Here you find an ESP8266/ESP32 version of IRremote with an impressive list of supported protocols.
Subject | IRMP | IRLremote |
IRLib2
mostly unmaintained |
IRremote | TinyIR | IRsmallDecoder |
Number of protocols | 50 | Nec + Panasonic + Hash * | 12 + Hash * | 17 + PulseDistance + Hash * | NEC + FAST | NEC + RC5 + Sony + Samsung |
Timing method receive | Timer2 or interrupt for pin 2 or 3 | Interrupt | Timer2 or interrupt for pin 2 or 3 | Timer2 | Interrupt | Interrupt |
Timing method send | PWM and timing with Timer2 interrupts | Timer2 interrupts | Timer2 and blocking wait |
PWM with Timer2 and/or blocking wait with delay
Microseconds() |
blocking wait with delay
Microseconds() |
|
Send pins | All | All | All ? | Timer dependent | All | |
Decode method | OnTheFly | OnTheFly | RAM | RAM | OnTheFly | OnTheFly |
Encode method | OnTheFly | OnTheFly | OnTheFly | OnTheFly or RAM | OnTheFly | |
Callback support | ||||||
Repeat handling | Receive + Send (partially) | Receive + Send | Receive + Send | Receive | ||
LED feedback | Receive | |||||
FLASH usage (simple NEC example with 5 prints) |
1820
(4300 for 15 main / 8000 for all 40 protocols) (+200 for callback) (+80 for interrupt at pin 2+3) |
1270
(1400 for pin 2+3) |
4830 | 1770 | 900 | ?1100? |
RAM usage |
52
(73 / 100 for 15 (main) / 40 protocols) |
62 | 334 | 227 | 19 | 29 |
Supported platforms |
avr, megaavr, attiny, Digispark (Pro), esp8266, ESP32, STM32, SAMD 21, Apollo3
(plus arm and pic for non Arduino IDE) |
avr, esp8266 | avr, SAMD 21, SAMD 51 | avr, attiny, esp8266, esp32, SAM, SAMD |
All platforms with attach
Interrupt() |
All platforms with attach
Interrupt() |
Last library update | 5/2023 | 4/2018 | 11/2022 | 9/2023 | 5/2023 | 2/2022 |
Remarks |
Decodes 40 protocols concurrently.
39 Protocols to send. Work in progress. |
Only one protocol at a time. | Consists of 5 libraries. *Project containing bugs – 63 issues, 10 pull requests. |
Universal decoder and encoder.
Supports Pronto codes and sending of raw timing values. |
Requires no timer. | Requires no timer. |
* The Hash protocol gives you a hash as code, which may be sufficient to distinguish your keys on the remote, but may not work with some protocols like Mitsubishi
Useful links
- List of public IR code databases
- LIRC database
- IRMP list of IR protocols
- IRDB database for IR codes
- IRP definition files for IR protocols
- IR Remote Control Theory and some protocols (upper right hamburger icon)
- Interpreting Decoded IR Signals (v2.45)
- “Recording long Infrared Remote control signals with Arduino”
- The original blog post of Ken Shirriff A Multi-Protocol Infrared Remote Library for the Arduino
- Vishay datasheet
License
Up to the version 2.7.0, the License is GPLv2. From the version 2.8.0, the license is the MIT license.
Copyright
Initially coded 2009 Ken Shirriff http://www.righto.comCopyright (c) 2016-2017 Rafi KhanCopyright (c) 2020-2023 Armin Joachimsmeyer
Problems with Neopixels, FastLed etc.
IRremote will not work right when you use Neopixels (aka WS2811/WS2812/WS2812B) or other libraries blocking interrupts for a longer time (> 50 µs).Whether you use the Adafruit Neopixel lib, or FastLED, interrupts get disabled on many lower end CPUs like the basic Arduinos for longer than 50 µs. In turn, this stops the IR interrupt handler from running when it needs to. See also this video.
One workaround is to wait for the IR receiver to be idle before you send the Neopixel data with
if (IrReceiver.isIdle()) { strip.show();}
.This prevents at least breaking a running IR transmission and -depending of the update rate of the Neopixel- may work quite well.There are some other solutions to this on more powerful processors, see this page from Marc MERLIN
Arduino Code
- Arduino code for DIYables 17-key IR remote controller
- Arduino code for DIYables 21-key IR remote controller
Quick Steps
- Navigate to the Libraries icon on the left bar of the Arduino IDE.
- Search “DIYables_IRcontroller”, then find the DIYables_IRcontroller library by DIYables
- Click Install button to install DIYables_IRcontroller library.
- You will be asked for installing the library dependency as below image:
- Click Install all button to install the dependency
- Copy the above code and open with Arduino IDE
- Click Upload button on Arduino IDE to upload code to Arduino
- Press keys on the remote controller one by one
- See the result on Serial Monitor.
- The below is the result when you press keys on 21-key IR controller one by one:
Now you can modify the code to control LED, fan, pump, actuator… via IR remote controllers.
Map each button to a number
Now we need to map each button to a number, and save that into our program, so we can recognize which button was actually pressed.
Because with just the previous code, well, what does “12” means? In my specific case, “12” means that I pressed on the button “1” of the remote controller.
Here I’m going to show you the step by step process to map each button you want to use, to an actual number in your code.
Important note: each remote controller will produce different numbers. I got “12” for button “1” but you’re probably going to have something different for each controller you try.
Watch this video as an additional resource to this tutorial (steps 1-2-3 for mapping buttons):
After watching the video, subscribe to the Robotics Back-End Youtube channel so you don’t miss the next tutorials!
Step 1: Setup – Print number for the buttons you want
Let’s use the same code we wrote just before.
Run the code on your Arduino and open the Serial Monitor.
For each button you want to use in your application, press the button and write down the number you get.
In my case, here is what I get:
- 12: button 1
- 24: button 2
- 94: button 3
- 64: button play/pause
Etc etc. Do this for each button you need. And once again, you will certainly have different values than me.
Step 2: Add the numbers into your program
Once you know what are the numbers for each button you’re going to use, add some defines at the top of your program.
#include
#define IR_RECEIVE_PIN 8 #define IR_BUTTON_1 12 #define IR_BUTTON_2 24 #define IR_BUTTON_3 94 #define IR_BUTTON_PLAY_PAUSE 64 …
Now, you don’t need to worry about the numbers anymore, you can just use IR_BUTTON_1 when you want to use button 1.
Step 3: Write your application program
After you’ve done the setup, you don’t need to print the number every time on the Serial monitor. You can remove the unneeded lines and write your application, using for example a switch structure.
#include
#define IR_RECEIVE_PIN 8 #define IR_BUTTON_1 12 #define IR_BUTTON_2 24 #define IR_BUTTON_3 94 #define IR_BUTTON_PLAY_PAUSE 64 void setup() { Serial.begin(9600); IrReceiver.begin(IR_RECEIVE_PIN); } void loop() { if (IrReceiver.decode()) { IrReceiver.resume(); int command = IrReceiver.decodedIRData.command; switch (command) { case IR_BUTTON_1: { Serial.println(“Pressed on button 1”); break; } case IR_BUTTON_2: { Serial.println(“Pressed on button 2”); break; } case IR_BUTTON_3: { Serial.println(“Pressed on button 3”); break; } case IR_BUTTON_PLAY_PAUSE: { Serial.println(“Pressed on button play/pause”); break; } default: { Serial.println(“Button not recognized”); } } } }
As you can see, for each button we have mapped, we add one more block of code in the switch.
When you press on a button, the IR receiver will send the corresponding number to the Arduino. Then in your code, you get the data with IrReceiver.decodedIRData.command. And then, in the switch, depending on which value you have, you will execute a different action.
If you run the code and press on some buttons, you’ll get something like this in the Serial Monitor.
Pressed on button 1 Pressed on button 2 Pressed on button 3 Pressed on button 3 Button not recognized Pressed on button play/pause
Now, you can use this code structure as a template for any project you do with an IR remote controller. Just remember to repeat steps 1 and 2 for each new controller you use, because you’re going to have different numbers for the buttons.
You can also decide to use an “if/else if/else” structure instead of the switch. This will work the same, but it’s maybe a bit cleaner with the switch.
How IR Remotes and Receivers Work
A typical infrared communication system requires an IR transmitter and an IR receiver. The transmitter looks just like a standard LED, except it produces light in the IR spectrum instead of the visible spectrum. If you have a look at the front of a TV remote, you’ll see the IR transmitter LED:
The same type of LED is used in IR transmitter breakout boards for the Arduino. You can see it at the front of this Keyes IR transmitter:
The IR receiver is a photodiode and pre-amplifier that converts the IR light into an electrical signal. IR receiver diodes typically look like this:
Some may come on a breakout board like this:
IR Signal Modulation
IR light is emitted by the sun, light bulbs, and anything else that produces heat. That means there is a lot of IR light noise all around us. To prevent this noise from interfering with the IR signal, a signal modulation technique is used.
In IR signal modulation, an encoder on the IR remote converts a binary signal into a modulated electrical signal. This electrical signal is sent to the transmitting LED. The transmitting LED converts the modulated electrical signal into a modulated IR light signal. The IR receiver then demodulates the IR light signal and converts it back to binary before passing on the information to a microcontroller:
The modulated IR signal is a series of IR light pulses switched on and off at a high frequency known as the carrier frequency. The carrier frequency used by most transmitters is 38 kHz, because it is rare in nature and thus can be distinguished from ambient noise. This way the IR receiver will know that the 38 kHz signal was sent from the transmitter and not picked up from the surrounding environment.
The receiver diode detects all frequencies of IR light, but it has a band-pass filter and only lets through IR at 38 kHz. It then amplifies the modulated signal with a pre-amplifier and converts it to a binary signal before sending it to a microcontroller.
IR Transmission Protocols
The pattern in which the modulated IR signal is converted to binary is defined by a transmission protocol. There are many IR transmission protocols. Sony, Matsushita, NEC, and RC5 are some of the more common protocols.
The NEC protocol is also the most common type in Arduino projects, so I’ll use it as an example to show you how the receiver converts the modulated IR signal to a binary one.
Logical ‘1’ starts with a 562.5 µs long HIGH pulse of 38 kHz IR followed by a 1,687.5 µs long LOW pulse. Logical ‘0’ is transmitted with a 562.5 µs long HIGH pulse followed by a 562.5 µs long LOW pulse:
This is how the NEC protocol encodes and decodes the binary data into a modulated signal. Other protocols differ only in the duration of the individual HIGH and LOW pulses.
IR Codes
Each time you press a button on the remote control, a unique hexadecimal code is generated. This is the information that is modulated and sent over IR to the receiver. In order to decipher which key is pressed, the receiving microcontroller needs to know which code corresponds to each key on the remote.
Different remotes send different codes for the keypresses, so you’ll need to determine the code generated for each key on your particular remote. If you can find the datasheet, the IR key codes should be listed. If not though, there is a simple Arduino sketch that will read most of the popular remote controls and print the hexadecimal codes to the serial monitor when you press a key. I’ll show you how to set that up in a minute, but first we need to connect the receiver to the Arduino…
Increase strength of sent output signal
The best way to increase the IR power for free is to use 2 or 3 IR diodes in series. One diode requires 1.2 volt at 20 mA or 1.5 volt at 100 mA so you can supply up to 3 diodes with a 5 volt output.To power 2 diodes with 1.2 V and 20 mA and a 5 V supply, set the resistor to: (5 V – 2.4 V) -> 2.6 V / 20 mA = 130 Ω.For 3 diodes it requires 1.4 V / 20 mA = 70 Ω.The actual current might be lower since of loss at the AVR pin. E.g. 0.3 V at 20 mA.If you do not require more current than 20 mA, there is no need to use an external transistor (at least for AVR chips).
On my Arduino Nanos, I always use a 100 Ω series resistor and one IR LED 😀.
Using the IR Remote to Control Things
Now I’ll show you a simple demonstration of how you can use the IR remote to control the Arduino’s output pins. In this example, we will light up an LED when a particular button is pressed. You can easily modify the code to do things like control servo motors, or activate relays with any button press from the remote.
The example circuit has the IR receiver connected to the Arduino, with a red LED connected to pin 10 and a green LED connected to pin 11:
The code below will write digital pin 10 HIGH for 2 seconds when the “5” button is pressed, and write digital pin 11 HIGH for 2 seconds when the “2” button is pressed:
#include
const int RECV_PIN = 7; IRrecv irrecv(RECV_PIN); decode_results results; const int redPin = 10; const int greenPin = 11; void setup(){ irrecv.enableIRIn(); irrecv.blink13(true); pinMode(redPin, OUTPUT); pinMode(greenPin, OUTPUT); } void loop(){ if (irrecv.decode(&results)){ switch(results.value){ case 0xFF38C7: //Keypad button "5" digitalWrite(redPin, HIGH); delay(2000); digitalWrite(redPin, LOW); } switch(results.value){ case 0xFF18E7: //Keypad button "2" digitalWrite(greenPin, HIGH); delay(2000); digitalWrite(greenPin, LOW); } irrecv.resume(); } }
So far we have covered the properties of infrared radiation and how communication happens between the transmitter and receiver. We saw how to identify the IR key codes for a given remote control. We learned how to display key presses on serial monitor and on an LCD screen. Finally I showed you how to control the Arduino’s output with the remote. Have fun playing with this and be sure to let us know in the comments if you have any questions or trouble setting this up!
In this tutorial I will show you how to setup and use an IR (InfraRed) remote controller with Arduino.
You will learn how to map each button of the controller to a specific action, so you can make your Arduino programs more dynamic.
After reading this post you will be able to fully integrate any IR remote controller to any of your Arduino projects.
Table of Contents
Disclaimer
This library was designed to fit inside MCUs with relatively low levels of resources and was intended to work as a library together with other applications which also require some resources of the MCU to operate.
For air conditioners see this fork, which supports an impressive set of protocols and a lot of air conditioners.
For long signals see the blog entry: “Recording long Infrared Remote control signals with Arduino”.
Hardware-PWM signal generation for sending
If you define
SEND_PWM_BY_TIMER
, the send PWM signal is forced to be generated by a hardware timer on most platforms.By default, the same timer as for the receiver is used.Since each hardware timer has its dedicated output pin(s), you must change timer or timer sub-specifications to change PWM output pin. See private/IRTimer.hppExeptions are currently ESP32, ARDUINO_ARCH_RP2040, PARTICLE and ARDUINO_ARCH_MBED, where PWM generation does not require a timer.
Bài viết liên quan
- Bài 13: Điều khiển động cơ quạt bằng nút nhấn sử dụng Arduino
- Bài 12: Thay đổi màu sắc LED RGB bằng biến trở sử dụng Arduino
- Bài 11: Điều khiển động cơ Servo bằng biến trở sử dụng Arduino
- Bài 10: Điều khiển động cơ RC Servo sử dụng Arduino
- Bài 9: Cảm biến ánh sáng (Quang trở) cách chia điện áp trong môi trường Arduino
- Bài 8: Cảm biến góc nghiêng sử dụng ngắt (INTERRUPT) trong môi trường Arduino
- Bài 7: Cảnh báo nhiệt độ (LM35) bằng còi báo sử dụng Arduino Uno
- Bài 6: Tạo âm thanh (Còi) bằng Arduino
- Bài 5: Thay đổi màu sắc Led RGB sử dụng Arduino
- Bài 4: PWM | Thay đổi ánh sáng của LED trên Arduino
- Bài 3: Sử dụng Arduino làm hệ thống đèn giao thông
- Bài 2: Chớp tắt LED trên Arduino Uno (Phần 2)
- Bài 1: Chớp tắt LED trên Arduino Uno
Arduino – IR Remote Control
You’ve likely encountered the infrared remote controller, also known as the IR remote controller, while using home electronic devices like TVs and air conditioners… In this tutorial, we are going to learn how to use infrared (IR) remote controller and infrared receiver to control Arduino. In detail, we will learn:
- How to connect an IR receiver to Arduino board
- How to program Arduino to read the command from IR remote controller via IR receiver
Then you can modify the code to control LED, fan, pump, actuator… via IR remote controller.
Step 7: Works on Any Remote!
Now go grab a bunch or remotes from around the house, and give those a try! I got a direct-tv remote and the smartphone pod/remote for a Helo TC remote controlled helicopter. This circuit showed the code for both of these remotes.
Here is the project that inspired me to write this up!
How To Use IR
Some Android devices have a built-in IR transceiver. This means that they can send and receive IR signals (the same thing used by your typical TV remote control). This makes it possible to control TVs, steros, and other equipment with Unified Remote.
Only certain Android devices are supported for IR. Note that Sony devices are not supported at the moment.
- HTC One
- LG G3 Transmitting and learning supported (Learned code will only work on LG G3)
- Samsung devices with IR (S4, S6, Note 3, etc)
Create a Widget or Quick Actions and edit a button.
There are 3 different modes for specifying the IR command.
- Lookup lets you search for a known IR code in a database.
- Learn lets you use your device IR sensor to recognize the code from a remote control.
- Input lets you enter a Pronto Code (which can be found on various web sites).
To Lookup a code, enter the manufacturer name of the device you want to control, select the device, and then select a code set. The code sets are not linked to specific models. Select a code set and then test a button to see if it is the correct code set for your device. It is a trial and error process unfortunately.
To Learn a code, follow the instructions on shown in the app. The instructions may vary for different Android devices. Note that it may take several attempts to capture the code correctly.
To Input a code you can try to search for the IR codes for your device. The best online resource is www.remotecentral.com. Make sure you enter codes in Pronto format only.
Use an IR Receiver with Arduino
Application example: blink some LEDs with the IR remote controller
In this application, what we want to do is simply to toggle a red LED when we press on button 2, and toggle a green LED when we press on button play/pause.
Circuit
Let’s build this circuit.
We use the same circuit as before, and add 2 LEDs:
- For each LED, plug the shorter leg to GND.
- plug the longer leg to a 220Ohm resistor.
- Connect the other leg of the resistor to pin 12 (red LED) and pin 11 (green LED).
Code
Here is the code for the application.
#include
#define IR_RECEIVE_PIN 8 #define IR_BUTTON_2 24 #define IR_BUTTON_PLAY_PAUSE 64 #define RED_LED_PIN 12 #define GREEN_LED_PIN 11 byte redLedState = LOW; byte greenLedState = LOW; void setup() { IrReceiver.begin(IR_RECEIVE_PIN); pinMode(RED_LED_PIN, OUTPUT); pinMode(GREEN_LED_PIN, OUTPUT); } void loop() { if (IrReceiver.decode()) { IrReceiver.resume(); int command = IrReceiver.decodedIRData.command; switch (command) { case IR_BUTTON_2: { redLedState = (redLedState == LOW) ? HIGH : LOW; digitalWrite(RED_LED_PIN, redLedState); break; } case IR_BUTTON_PLAY_PAUSE: { greenLedState = (greenLedState == LOW) ? HIGH: LOW; digitalWrite(GREEN_LED_PIN, greenLedState); break; } default: { // do nothing } } } }
If you run this, and press on button “play/pause”, you will see the green LED powered on. If you press again, the green LED will be powered off. Etc. The same applies for the red LED when you press on the button “2”.
And let’s now break the code down.
#include
#define IR_RECEIVE_PIN 8 #define IR_BUTTON_2 24 #define IR_BUTTON_PLAY_PAUSE 64
As we have already mapped the buttons, we reuse the same defines we previously wrote. Here we just need buttons “2” and “play/pause” so I’ve only included the numbers for those 2 buttons.
#define RED_LED_PIN 12 #define GREEN_LED_PIN 11 byte redLedState = LOW; byte greenLedState = LOW;
We set some defines for the LED’s pin numbers. We also keep the state of both LEDs in a global variable, so we will be able to retrieve and toggle this state.
void setup() { IrReceiver.begin(IR_RECEIVE_PIN); pinMode(RED_LED_PIN, OUTPUT); pinMode(GREEN_LED_PIN, OUTPUT); }
In the setup() we initialize the IR receiver component, and the 2 LEDs with pinMode() function and OUTPUT mode.
void loop() { if (IrReceiver.decode()) { IrReceiver.resume(); int command = IrReceiver.decodedIRData.command; switch (command) {
This is exactly the same as what we did before. We check if there is some data to read from the IR receiver. If yes, we get the data, we resume the sensor, and we check which button was pressed with a switch structure.
case IR_BUTTON_2: { redLedState = (redLedState == LOW) ? HIGH : LOW; digitalWrite(RED_LED_PIN, redLedState); break; }
When the button “2” is pressed, we toggle the LED state with a one-liner: (redLedState == LOW) will be evaluated to true or false. If it’s true (variable is LOW), we set the variable to HIGH, and if it’s false (variable is HIGH), we set the variable to LOW.
After that we apply the new state to the LED with digitalWrite().
That’s it! If you know how to toggle an LED, and how to get data from an IR receiver, combining the 2 together is really easy.
case IR_BUTTON_PLAY_PAUSE: { greenLedState = (greenLedState == LOW) ? HIGH: LOW; digitalWrite(GREEN_LED_PIN, greenLedState); break; }
We do the same thing for the green LED, when we press on the “play/pause” button.
default: { // do nothing } } } }
And finally we have the switch default, which we don’t use here.
New features with version 3.x
-
Any pin can be used for sending -if
SEND_PWM_BY_TIMER
is not defined- and receiving. - Feedback LED can be activated for sending / receiving.
- An 8/16 bit **command value as well as an 16 bit address and a protocol number is provided for decoding (instead of the old 32 bit value).
- Protocol values comply to protocol standards.NEC, Panasonic, Sony, Samsung and JVC decode & send LSB first.
- Supports Universal Distance protocol, which covers a lot of previous unknown protocols.
- Compatible with tone() library. See the ReceiveDemo example.
- Simultaneous sending and receiving. See the SendAndReceive example.
- Supports more platforms.
- Allows for the generation of non PWM signal to just simulate an active low receiver signal for direct connect to existent receiving devices without using IR.
- Easy protocol configuration, directly in your source code.Reduces memory footprint and decreases decoding time.
- Contains a very small NEC only decoder, which does not require any timer resource.
-> Feature comparison of 5 Arduino IR libraries.
Converting your 2.x program to the 4.x version
Starting with the 3.1 version, the generation of PWM for sending is done by software, thus saving the hardware timer and enabling arbitrary output pins for sending.If you use an (old) Arduino core that does not use the
-flto
flag for compile, you can activate the line
#define SUPPRESS_ERROR_MESSAGE_FOR_BEGIN
in IRRemote.h, if you get false error messages regarding begin() during compilation.
-
IRreceiver and IRsender object have been added and can be used without defining them, like the well known Arduino Serial object.
-
Just remove the line
IRrecv IrReceiver(IR_RECEIVE_PIN);
and/or
IRsend IrSender;
in your program, and replace all occurrences of
IRrecv.
or
irrecv.
with
IrReceiver
and replace all
IRsend
or
irsend
with
IrSender
. -
Since the decoded values are now in
IrReceiver.decodedIRData
and not in
results
any more, remove the line
decode_results results
or similar. -
Like for the Serial object, call
IrReceiver.begin(IR_RECEIVE_PIN, ENABLE_LED_FEEDBACK)
or
IrReceiver.begin(IR_RECEIVE_PIN, DISABLE_LED_FEEDBACK)
instead of the
IrReceiver.enableIRIn()
or
irrecv.enableIRIn()
in setup().For sending, call
IrSender.begin();
or
IrSender.begin(DISABLE_LED_FEEDBACK);
in setup().If IR_SEND_PIN is not defined (before the line
#include
) you must use e.g.
IrSender.begin(3, ENABLE_LED_FEEDBACK, USE_DEFAULT_FEEDBACK_LED_PIN);
-
Old
decode(decode_results *aResults)
function is replaced by simple
decode()
. So if you have a statement
if(irrecv.decode(&results))
replace it with
if (IrReceiver.decode())
. -
The decoded result is now in in
IrReceiver.decodedIRData
and not in
results
any more, therefore replace any occurrences of
results.value
and
results.decode_type
(and similar) to
IrReceiver.decodedIRData.decodedRawData
and
IrReceiver.decodedIRData.protocol
. -
Overflow, Repeat and other flags are now in
IrReceiver.receivedIRData.flags
. -
Seldom used:
results.rawbuf
and
results.rawlen
must be replaced by
IrReceiver.decodedIRData.rawDataPtr->rawbuf
and
IrReceiver.decodedIRData.rawDataPtr->rawlen
. -
The 5 protocols NEC, Panasonic, Sony, Samsung and JVC have been converted to LSB first. Send functions for sending old MSB data for NEC and JVC were renamed to
sendNECMSB
, and
sendJVCMSB()
. The old
sendSAMSUNG()
and
sendSony()
MSB functions are still available. The old MSB version of
sendPanasonic()
function was deleted, since it had bugs nobody recognized.For converting MSB codes to LSB see below.
Example
Old 2.x program:
#include
#define RECV_PIN 2 IRrecv irrecv(RECV_PIN); decode_results results; void setup() { … irrecv.enableIRIn(); // Start the receiver } void loop() { if (irrecv.decode(&results)) { Serial.println(results.value, HEX); … irrecv.resume(); // Receive the next value } … }
New 4.x program:
#include
#define IR_RECEIVE_PIN 2 void setup() { … IrReceiver.begin(IR_RECEIVE_PIN, ENABLE_LED_FEEDBACK); // Start the receiver } void loop() { if (IrReceiver.decode()) { Serial.println(IrReceiver.decodedIRData.decodedRawData, HEX); // Print “old” raw data // USE NEW 3.x FUNCTIONS IrReceiver.printIRResultShort(&Serial); // Print complete received data in one line IrReceiver.printIRSendUsage(&Serial); // Print the statement required to send this data … IrReceiver.resume(); // Enable receiving of the next value } … }
Map each button to a number
Now we need to map each button to a number, and save that into our program, so we can recognize which button was actually pressed.
Because with just the previous code, well, what does “12” means? In my specific case, “12” means that I pressed on the button “1” of the remote controller.
Here I’m going to show you the step by step process to map each button you want to use, to an actual number in your code.
Important note: each remote controller will produce different numbers. I got “12” for button “1” but you’re probably going to have something different for each controller you try.
Watch this video as an additional resource to this tutorial (steps 1-2-3 for mapping buttons):
After watching the video, subscribe to the Robotics Back-End Youtube channel so you don’t miss the next tutorials!
Step 1: Setup – Print number for the buttons you want
Let’s use the same code we wrote just before.
Run the code on your Arduino and open the Serial Monitor.
For each button you want to use in your application, press the button and write down the number you get.
In my case, here is what I get:
- 12: button 1
- 24: button 2
- 94: button 3
- 64: button play/pause
Etc etc. Do this for each button you need. And once again, you will certainly have different values than me.
Step 2: Add the numbers into your program
Once you know what are the numbers for each button you’re going to use, add some defines at the top of your program.
#include
#define IR_RECEIVE_PIN 8 #define IR_BUTTON_1 12 #define IR_BUTTON_2 24 #define IR_BUTTON_3 94 #define IR_BUTTON_PLAY_PAUSE 64 …
Now, you don’t need to worry about the numbers anymore, you can just use IR_BUTTON_1 when you want to use button 1.
Step 3: Write your application program
After you’ve done the setup, you don’t need to print the number every time on the Serial monitor. You can remove the unneeded lines and write your application, using for example a switch structure.
#include
#define IR_RECEIVE_PIN 8 #define IR_BUTTON_1 12 #define IR_BUTTON_2 24 #define IR_BUTTON_3 94 #define IR_BUTTON_PLAY_PAUSE 64 void setup() { Serial.begin(9600); IrReceiver.begin(IR_RECEIVE_PIN); } void loop() { if (IrReceiver.decode()) { IrReceiver.resume(); int command = IrReceiver.decodedIRData.command; switch (command) { case IR_BUTTON_1: { Serial.println(“Pressed on button 1”); break; } case IR_BUTTON_2: { Serial.println(“Pressed on button 2”); break; } case IR_BUTTON_3: { Serial.println(“Pressed on button 3”); break; } case IR_BUTTON_PLAY_PAUSE: { Serial.println(“Pressed on button play/pause”); break; } default: { Serial.println(“Button not recognized”); } } } }
As you can see, for each button we have mapped, we add one more block of code in the switch.
When you press on a button, the IR receiver will send the corresponding number to the Arduino. Then in your code, you get the data with IrReceiver.decodedIRData.command. And then, in the switch, depending on which value you have, you will execute a different action.
If you run the code and press on some buttons, you’ll get something like this in the Serial Monitor.
Pressed on button 1 Pressed on button 2 Pressed on button 3 Pressed on button 3 Button not recognized Pressed on button play/pause
Now, you can use this code structure as a template for any project you do with an IR remote controller. Just remember to repeat steps 1 and 2 for each new controller you use, because you’re going to have different numbers for the buttons.
You can also decide to use an “if/else if/else” structure instead of the switch. This will work the same, but it’s maybe a bit cleaner with the switch.
New features with version 4.x
- New universal Pulse Distance / Pulse Width decoder added, which covers many previous unknown protocols.
-
Printout of code how to send received command by
IrReceiver.printIRSendUsage(&Serial)
. -
RawData type is now 64 bit for 32 bit platforms and therefore
decodedIRData.decodedRawData
can contain complete frame information for more protocols than with 32 bit as before. - Callback after receiving a command – It calls your code as soon as a message was received.
-
Improved handling of
PULSE_DISTANCE
+
PULSE_WIDTH
protocols. - New FAST protocol.
Converting your 3.x program to the 4.x version
-
You must replace
#define DECODE_DISTANCE
by
#define DECODE_DISTANCE_WIDTH
(only if you explicitly enabled this decoder). -
The parameter
bool hasStopBit
is not longer required and removed e.g. for function
sendPulseDistanceWidth()
.
Bang & Olufsen protocol
The Bang & Olufsen protocol decoder is not enabled by default, i.e if no protocol is enabled explicitly by #define
DECODE_
. It must always be enabled explicitly by
#define DECODE_BEO
.
This is because it has an IR transmit frequency of 455 kHz and therefore requires a different receiver hardware (TSOP7000).And because generating a 455 kHz PWM signal is currently only implemented for
SEND_PWM_BY_TIMER
, sending only works if
SEND_PWM_BY_TIMER
or
USE_NO_SEND_PWM
is defined.For more info, see ir_BangOlufsen.hpp.
Handling unknown Protocols
Multiple IR receivers
IRreceiver consists of one timer triggered function reading the digital IR signal value from one pin every 50 µs.So multiple IR receivers can only be used by connecting the output pins of several IR receivers together. The IR receivers use an NPN transistor as output device with just a 30k resistor to VCC. This is almost “open collector” and allows connecting of several output pins to one Arduino input pin.But keep in mind, that any weak / disturbed signal from one of the receivers will in turn also disturb a good signal from another one.
Send pin
Any pin can be choosen as send pin, because the PWM signal is generated by default with software bit banging, since
SEND_PWM_BY_TIMER
is not active.
If
IR_SEND_PIN
is specified (as c macro), it reduces program size and improves send timing for AVR. If you want to use a variable to specify send pin e.g. with
setSendPin(uint8_t aSendPinNumber)
, you must disable this
IR_SEND_PIN
macro. Then you can change send pin at any time before sending an IR frame. See also Compile options / macros for this library.
List of public IR code databases
http://www.harctoolbox.org/IR-resources.html
Step 2: Download IR Library
In order to reverse engineer the remote and obtain the codes for each button we are going to need to download and install the following library.https://github.com/shirriff/Arduino-IRremoteExtract the file in your libraries directory. e.g. ( C:\electronics\arduino-1.0.5\libraries )note: I had to rename the library because the name was too long, I just renamed it to IR.
Wiring Diagram
Wiring diagram between Arduino and IR Receiver Module
This image is created using Fritzing. Click to enlarge image
The real wiring diagram
Wiring diagram between Arduino and IR Receiver Sensor
This image is created using Fritzing. Click to enlarge image
The real wiring diagram
Wiring diagram between Arduino and IR Receiver Sensor and Adapter
You can also connect The IR receiver sensor to the adapter before connecting to the Arduino.
Components and supplies
IR receiver (generic)
Arduino UNO
JustBoom IR Remote
Tools and machines
IR Remote Libary
Apps and platforms
Arduino IDE
Project description
Code
Code
c_cpp
Upload the Code and See the Code of Button Pressed in Serial Monitor
Downloadable files
Circuit Diagram
1. Connect the First pin from the left of TSOP1738 (OUT pin) with pin 11 of Arduino. 2. Hook the Middle pin (GND pin) with the GND pin of Arduino. 3. Connect the third and the last pin (VCC pin) with 5V pin of Arduino.
Circuit Diagram
Circuit Diagram
1. Connect the First pin from the left of TSOP1738 (OUT pin) with pin 11 of Arduino. 2. Hook the Middle pin (GND pin) with the GND pin of Arduino. 3. Connect the third and the last pin (VCC pin) with 5V pin of Arduino.
Circuit Diagram
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Table of contents
Intro
Infrared (IR) communication is a widely used and easy to implement wireless technology that has many useful applications. The most prominent examples in day to day life are TV/video remote controls, motion sensors, and infrared thermometers.
There are plenty of interesting Arduino projects that use IR communication too. With a simple IR transmitter and receiver, you can make remote controlled robots, distance sensors, heart rate monitors, DSLR camera remote controls, TV remote controls, and lots more.
In this tutorial I’ll first explain what infrared is and how it works. Then I’ll show you how to set up an IR receiver and remote on an Arduino. I’ll also show you how to use virtually any IR remote (like the one for your TV) to control things connected to the Arduino.
Watch the video for this tutorial here:
Now let’s get into the details…
Staying on 2.x
Consider using the original 2.4 release form 2017
or the last backwards compatible 2.8 version for you project.It may be sufficient and deals flawlessly with 32 bit IR codes.If this doesn’t fit your case, be assured that 3.x is at least trying to be backwards compatible, so your old examples should still work fine.
Drawbacks
-
Only the following decoders are available:
NEC
Denon
Panasonic
JVC
LG
RC5
RC6
Samsung
Sony
-
The call of
irrecv.decode(&results)
uses the old MSB first decoders like in 2.x and sets the 32 bit codes in
results.value
. -
The old functions
sendNEC()
and
sendJVC()
are renamed to
sendNECMSB()
and
sendJVCMSB()
.Use them to send your old MSB-first 32 bit IR data codes. - No decoding by a (constant) 8/16 bit address and an 8 bit command.
Why *.hpp instead of *.cpp?
Every *.cpp file is compiled separately by a call of the compiler exclusively for this cpp file. These calls are managed by the IDE / make system. In the Arduino IDE the calls are executed when you click on Verify or Upload.
And now our problem with Arduino is:How to set compile options for all *.cpp files, especially for libraries used?IDE’s like Sloeber or PlatformIO support this by allowing to specify a set of options per project. They add these options at each compiler call e.g.
-DTRACE
.
But Arduino lacks this feature.
So the workaround is not to compile all sources separately, but to concatenate them to one huge source file by including them in your source.This is done by e.g.
#include "IRremote.hpp"
.
But why not
#include "IRremote.cpp"
?Try it and you will see tons of errors, because each function of the *.cpp file is now compiled twice, first by compiling the huge file and second by compiling the *.cpp file separately, like described above.So using the extension cpp is not longer possible, and one solution is to use hpp as extension, to show that it is an included *.cpp file.Every other extension e.g. cinclude would do, but hpp seems to be common sense.
Using the new *.hpp files
In order to support compile options more easily,
you must use the statement
#include
instead of
#include
in your main program (aka *.ino file with setup() and loop()).
In all other files you must use the following, to prevent
multiple definitions
linker errors:
#define USE_IRREMOTE_HPP_AS_PLAIN_INCLUDE #include
Ensure that all macros in your main program are defined before any
#include
.The following macros will definitely be overridden with default values otherwise:
-
RAW_BUFFER_LENGTH
-
IR_SEND_PIN
-
SEND_PWM_BY_TIMER
Receiving IR codes
Check for a completly received IR frame with:
if (IrReceiver.decode()) {}
This also decodes the received data.After successful decoding, the IR data is contained in the IRData structure, available as
IrReceiver.decodedIRData
.
What is Infrared?
Infrared radiation is a form of light similar to the light we see all around us. The only difference between IR light and visible light is the frequency and wavelength. Infrared radiation lies outside the range of visible light, so humans can’t see it:
Because IR is a type of light, IR communication requires a direct line of sight from the receiver to the transmitter. It can’t transmit through walls or other materials like WiFi or Bluetooth.
Step 6: Record Button Codes
Here are the codes that I got for the white remote. FFFFFF is a repeat command, you’ll get a stream of them if you hold down a button.PWR FF629DCH FFE21D|<< FF22DD>| FFC23D>>| FF02FD- FFE01FPlus FFA857EQ FF906F0 FF6897100 FF9867200 FFB04F1 FF30CF2 FF18E73 FF7A854 FF10EF5 FF38C76 FF5AA57 FF42BD8 FF48B59 FF52ADand here are the codes I got from the black remote.PWR FD00FFVOL FD807FFUNC/STOP FD40BF|<< FD20DF>| FDA05F>>| FD609FDOWN FD10EFVOL FD906FUP FD50AF0 FD30CFEQ FDB04FST/REPT FD708F1 FD08F72 FD88773 FD48B74 FD28D75 FDA8576 FD68977 FD18E78 FD98679 FD58A7
Read data from the IR remote controller
Here is the code to print the corresponding data for each button you press.
#include
#define IR_RECEIVE_PIN 8 void setup() { Serial.begin(9600); IrReceiver.begin(IR_RECEIVE_PIN); } void loop() { if (IrReceiver.decode()) { IrReceiver.resume(); Serial.println(IrReceiver.decodedIRData.command); } }
Let’s break this down line by line.
#include
#define IR_RECEIVE_PIN 8
First you need to include the library you’ve just installed. We also use a define for the data pin of the IR receiver.
void setup() { Serial.begin(9600); IrReceiver.begin(IR_RECEIVE_PIN); }
In the void setup() function, we initialize the Serial communication and the IR receiver. For the IR receiver, you use the begin() function with one argument: the number of the data pin for the IR receiver.
void loop() { if (IrReceiver.decode()) { IrReceiver.resume(); Serial.println(IrReceiver.decodedIRData.command); } }
In the void loop() function, we continuously check if some new data is available with IrReceiver.decode(). If yes, we immediately call IrReceiver.resume() so that the sensor will continue to read data – if you don’t do this you will get weird errors.
And to get access to the data, we need to use IrReceiver.decodedIRData.command.
If you run this program on your Arduino, and open the Serial Monitor, you’ll see something like this:
12 24 94 28
For each button you press, you’ll get a number.
Flipper Zero
Flipper decoding | IRremote decoding |
Samsung32 | Samsung |
NEC | NEC |
NECext | ONKYO |
and ID is MSB of address. address: 8A 02 20 00 command: 56 03 00 00 -> IRremote: Address 0x6A8, sendPanasonic (for 02 20) and Command 0x35 |
Tiny NEC receiver and sender
For applications only requiring NEC, NEC variants or FAST -see below- protocol, there is a special receiver / sender included,which has very small code size of 500 bytes and does NOT require any timer.
Check out the TinyReceiver and IRDispatcherDemo examples.Take care to include
TinyIRReceiver.hpp
or
TinyIRSender.hpp
instead of
IRremote.hpp
.
TinyIRReceiver usage
//#define USE_ONKYO_PROTOCOL // Like NEC, but take the 16 bit address and command each as one 16 bit value and not as 8 bit normal and 8 bit inverted value. //#define USE_FAST_PROTOCOL // Use FAST protocol instead of NEC / ONKYO #include “TinyIRReceiver.hpp” void setup() { initPCIInterruptForTinyReceiver(); // Enables the interrupt generation on change of IR input signal } void loop() { if (TinyIRReceiverData.justWritten) { TinyIRReceiverData.justWritten = false; printTinyReceiverResultMinimal(&Serial); } }
TinyIRSender usage
#include “TinyIRSender.hpp” void setup() { sendNEC(3, 0, 11, 2); // Send address 0 and command 11 on pin 3 with 2 repeats. } void loop() {}
Another tiny receiver and sender supporting more protocols can be found here.
The FAST protocol
The FAST protocol is a proprietary modified JVC protocol without address, with parity and with a shorter header. It is meant to have a quick response to the event which sent the protocol frame on another board. FAST takes 21 ms for sending and is sent at a 50 ms period. It has full 8 bit parity for error detection.
FAST protocol characteristics:
- Bit timing is like JVC
- The header is shorter, 3156 µs vs. 12500 µs
- No address and 16 bit data, interpreted as 8 bit command and 8 bit inverted command, leading to a fixed protocol length of (6 + (16 * 3) + 1) * 526 = 55 * 526 = 28930 microseconds or 29 ms.
- Repeats are sent as complete frames but in a 50 ms period / with a 21 ms distance.
Sending FAST protocol with IRremote
#define IR_SEND_PIN 3 #include
void setup() { sendFAST(11, 2); // Send command 11 on pin 3 with 2 repeats. } void loop() {}
Sending FAST protocol with TinyIRSender
#define USE_FAST_PROTOCOL // Use FAST protocol. No address and 16 bit data, interpreted as 8 bit command and 8 bit inverted command #include “TinyIRSender.hpp” void setup() { sendFAST(3, 11, 2); // Send command 11 on pin 3 with 2 repeats. } void loop() {}
The FAST protocol can be received by IRremote and TinyIRReceiver.
FAQ and hints
Arduino circuit with IR receiver and IR remote controller
For the circuit you will need:
- Arduino board (any version is fine, I will use Arduino Uno).
- breadboard.
- IR receiver. This will receive data from the remote controller and send it to the Arduino board.
- IR remote controller.
To build the circuit:
You are learning how to use Arduino to build your own projects?
Check out Arduino For Beginners and learn step by step.
- Place the IR receiver on the breadboard, with each pin on an independent line, so they are not connected with each other.
- Connect the GND pin of the IR receiver to one GND pin of the Arduino.
- Connect the Vcc or power pin of the IR receiver to the 5V pin of the Arduino.
- For the data pin, connect it to one digital pin of the Arduino (here digital pin number 8).
(more info on Arduino Uno pins)
Note that the IR receiver you have may be different from the one you see here on the picture. The order of the pins can also be different. The important thing is to locate first GND, Vcc, and data pins, and then connect them accordingly to the correct Arduino pins.
Code
#include
int RECV_PIN = 11; int ledPin = 10; boolean ledState = LOW; IRrecv irrecv(RECV_PIN); decode_results results; void setup(){ Serial.begin(9600); irrecv.enableIRIn(); pinMode(ledPin,OUTPUT); } void loop() { if (irrecv.decode(&results)) { Serial.println(results.value, HEX); if(results.value == 0xFD00FF){ ledState = !ledState; digitalWrite(ledPin,ledState); } irrecv.resume(); } }
Giải thích code
Đầu tiên kiểm tra xem remote đã nhận tín hiệu chưa nếu quá trình nhận tín hiệu thành công thì xuất ra màn hình giá trị mã HEX.
if (irrecv.decode(&results)) … if(results.value == 0xFD00FF)
Đảo trạng thái của LED
ledState = !ledState; digitalWrite(ledPin,ledState);
Nhận giá trị tiếp theo.
irrecv.resume();
Thư viện
Cài đặt thư viện IR Remote: Tải ngay
Protocol=PULSE_DISTANCE
If you get something like this:
PULSE_DISTANCE: HeaderMarkMicros=8900 HeaderSpaceMicros=4450 MarkMicros=550 OneSpaceMicros=1700 ZeroSpaceMicros=600 NumberOfBits=56 0x43D8613C 0x3BC3BC
then you have a code consisting of 56 bits, which is probably from an air conditioner remote.You can send it with sendPulseDistance().
uint32_t tRawData[] = { 0xB02002, 0xA010 }; IrSender.sendPulseDistance(38, 3450, 1700, 450, 1250, 450, 400, &tRawData[0], 48, false, 0, 0);
You can send it with calling sendPulseDistanceWidthData() twice, once for the first 32 bit and next for the remaining 24 bits.The PulseDistance or PulseWidth decoders just decode a timing steam to a bit stream. They can not put any semantics like address, command or checksum on this bitstream, since it is no known protocol. But the bitstream is way more readable, than a timing stream. This bitstream is read LSB first by default. If this does not suit you for further research, you can change it here.
Receive controls from your remote control!
Written By: Marcus Schappi
Difficulty
Easy
Steps
11
An IR receiver uses infrared communication. Infrared light, unlike visible light, has a slightly longer wavelength and so is undetectable to the human eye. But it is detectable by a TV which listens for IR signals.
In this guide, you will learn how to capture button presses on a remote with the 100% compatible Arduino development board, the Little Bird Uno R3 and an Arduino compatible IR receiver module. Have a try with a few different remote controls you have around the house!
After completing this guide, you will understand the basics involved and can use an IR receiver in your very own Arduino projects!
Connect Digital Pin 11 to the Signal Pin of the IR Receiver.
Connect 5V to the 5V (middle) Pin of the IR Receiver.
Connect Ground to the Ground Pin of the IR Receiver.
Insert the LED into the breadboard with the Cathode (shorter leg) on the left hand side.
Insert a 220 Ohm Resistor into the Breadboard with one leg in line with the LED’s anode (longer leg).
#include
#include
int RECV_PIN = 11; //define input pin on Arduino IRrecv irrecv(RECV_PIN); decode_results results; void setup() { Serial.begin(9600); irrecv.enableIRIn(); // Start the receiver pinMode(LED_BUILTIN, OUTPUT); } void loop() { if (irrecv.decode( & results)) { String hex = String(results.value, HEX); Serial.print(“Hexadecimal Code: “); Serial.println(hex); if(hex == “ff18e7”){ digitalWrite(LED_BUILTIN, HIGH); // turn the LED on (HIGH is the voltage level) } if(hex == “ff4ab5”){ digitalWrite(LED_BUILTIN, LOW); // turn the LED off by making the voltage LOW } irrecv.resume(); // Receive the next value } }
Copy this code and open it in your Arduino IDE.
This code won’t work without the IRremote Library (we’ll install that next).
Open the Arduino Library Manager by clicking on Sketch → Include Libraries → Manage Libraries.
Search for the IRremote Library and install the latest version.
Arduino IRremote
A library enabling the sending & receiving of infra-red signals.
Available as Arduino library “IRremote”.
If you find this program useful, please give it a star.
Overview
- Supported IR Protocols
- Features
- Converting your 2.x program to the 4.x version
- Errors with using the 3.x versions for old tutorials
- Why *.hpp instead of *.cpp
- Using the new *.hpp files
- Receiving IR codes
- Sending IR codes
- Tiny NEC receiver and sender
- The FAST protocol
- FAQ and hints
- Handling unknown Protocols
- Examples for this library
- WOKWI online examples
- Issues and discussions
- Compile options / macros for this library
- Supported Boards
- Timer and pin usage
- How we decode signals
- NEC encoding diagrams
- Quick comparison of 5 Arduino IR receiving libraries
- Useful links
- Contributors
- License
- Copyright
Supported IR Protocols
NEC / Onkyo / Apple
Denon / Sharp
Panasonic / Kaseikyo
JVC
LG
RC5
RC6
Samsung
Sony
Universal Pulse Distance
Universal Pulse Width
Hash
Pronto
BoseWave
Bang & Olufsen
Lego
FAST
Whynter
MagiQuest
Protocols can be switched off and on by defining macros before the line
#include
like here:
#define DECODE_NEC //#define DECODE_DENON #include
Features
- Lots of tutorials and examples.
- Actively maintained.
- Allows receiving and sending of raw timing data.
Conclusion – Arduino IR remote controller
In this tutorial you have seen how to integrate an IR remote controller to make your application more dynamic.
To recap:
- First build the circuit with an IR receiver. One of the pins contains the data, which you are going to connect to a digital pin on your Arduino board.
- Then, you need to map each button so you can know on what you’ve pressed in your code. To map the buttons, first upload a program to print the numbers you get. Create some defines to map those numbers to existing buttons – you will need to repeat this step for each new remote controller you use.
- Remove the printing number code, and write your application using the defines. In the void loop() function, you can use a switch structure to do a different action for each button.
Bài 14: Điều khiển LED bằng IR Remote sử dụng Arduino
Trong nội dung bài viết khóa học lập trình Arduino hôm mình mình xin gửi đến các bạn một chủ đề mới (linh kiện mới IR), dùng để điều khiển các thiết bị.
Thông qua bài viết các bạn sẽ nắm được chức năng cấu tạo của IR Receiver trong lập trình Arduino.
Với chủ đề hôm nay mình sẽ dùng ánh sáng hồng ngoại IR để bật tắt LED nhé.
IR Receiver
Bức xạ hồng ngoại (IR), hay ánh sáng hồng ngoại, là dạng năng lượng bức xạ mà mắt người không nhìn thấy nhưng chúng ta có thể cảm nhận dưới dạng nhiệt. Mọi vật trong vũ trụ đều phát bức xạ IR ở mức nào đó, song có hai nguồn dễ thấy nhất là mặt trời và ngọn lửa.
IR là một loại bức xạ điện từ, một dải liên tục tần số được tạo ra khi các nguyên tử hấp thụ và sau đó giải phóng năng lượng. Từ tần số cao nhất đến thấp nhất, bức xạ điện từ bao gồm tia gamma, tia X, bức xạ tử ngoại, ánh sáng nhìn thấy, bức xạ hồng ngoại, vi sóng và sóng vô tuyến.
Read data from the IR remote controller
Here is the code to print the corresponding data for each button you press.
#include
#define IR_RECEIVE_PIN 8 void setup() { Serial.begin(9600); IrReceiver.begin(IR_RECEIVE_PIN); } void loop() { if (IrReceiver.decode()) { IrReceiver.resume(); Serial.println(IrReceiver.decodedIRData.command); } }
Let’s break this down line by line.
#include
#define IR_RECEIVE_PIN 8
First you need to include the library you’ve just installed. We also use a define for the data pin of the IR receiver.
void setup() { Serial.begin(9600); IrReceiver.begin(IR_RECEIVE_PIN); }
In the void setup() function, we initialize the Serial communication and the IR receiver. For the IR receiver, you use the begin() function with one argument: the number of the data pin for the IR receiver.
void loop() { if (IrReceiver.decode()) { IrReceiver.resume(); Serial.println(IrReceiver.decodedIRData.command); } }
In the void loop() function, we continuously check if some new data is available with IrReceiver.decode(). If yes, we immediately call IrReceiver.resume() so that the sensor will continue to read data – if you don’t do this you will get weird errors.
And to get access to the data, we need to use IrReceiver.decodedIRData.command.
If you run this program on your Arduino, and open the Serial Monitor, you’ll see something like this:
12 24 94 28
For each button you press, you’ll get a number.
Arduino circuit with IR receiver and IR remote controller
For the circuit you will need:
- Arduino board (any version is fine, I will use Arduino Uno).
- breadboard.
- IR receiver. This will receive data from the remote controller and send it to the Arduino board.
- IR remote controller.
To build the circuit:
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Check out Arduino For Beginners and learn step by step.
- Place the IR receiver on the breadboard, with each pin on an independent line, so they are not connected with each other.
- Connect the GND pin of the IR receiver to one GND pin of the Arduino.
- Connect the Vcc or power pin of the IR receiver to the 5V pin of the Arduino.
- For the data pin, connect it to one digital pin of the Arduino (here digital pin number 8).
(more info on Arduino Uno pins)
Note that the IR receiver you have may be different from the one you see here on the picture. The order of the pins can also be different. The important thing is to locate first GND, Vcc, and data pins, and then connect them accordingly to the correct Arduino pins.
Install an Arduino library for the IR remote controller
Be reassured: you won’t have to write hundreds of lines of code to be able to decode the data you get from the IR receiver. Someone already did that for you. All you need to do is to install an Arduino library and use it.
To do that, open the Arduino IDE. Go to Tools > Manage Libraries.
You will get a new window, where you will see many available libraries that you can install. In the search bar, type “irremote”.
You will find this IRremote library (by shirrif, z3t0, ArminJo).
Select the latest version (whatever version is fine, it doesn’t have to be exactly the same as the one you see on the screenshot). The important thing is to have a version starting by at least 3. Don’t use version 2.
Click on “Install” and wait a few seconds. Then you can close the window, and restart the Arduino IDE.
The IRremote library is now installed and ready to be used!
(if you want to download a specific library version not available from the Arduino IDE, you can also directly get the library from GitHub)
Conclusion – Arduino IR remote controller
In this tutorial you have seen how to integrate an IR remote controller to make your application more dynamic.
To recap:
- First build the circuit with an IR receiver. One of the pins contains the data, which you are going to connect to a digital pin on your Arduino board.
- Then, you need to map each button so you can know on what you’ve pressed in your code. To map the buttons, first upload a program to print the numbers you get. Create some defines to map those numbers to existing buttons – you will need to repeat this step for each new remote controller you use.
- Remove the printing number code, and write your application using the defines. In the void loop() function, you can use a switch structure to do a different action for each button.
How to deal with protocols not supported by IRremote
If you do not know which protocol your IR transmitter uses, you have several choices.
- Use the IRreceiveDump example to dump out the IR timing. You can then reproduce/send this timing with the SendRawDemo example. For long codes with more than 48 bits like from air conditioners, you can change the length of the input buffer in IRremote.h.
- The IRMP AllProtocol example prints the protocol and data for one of the 40 supported protocols. The same library can be used to send this codes.
- If you have a bigger Arduino board at hand (> 100 kByte program memory) you can try the IRremoteDecode example of the Arduino library DecodeIR.
- Use IrScrutinizer. It can automatically generate a send sketch for your protocol by exporting as “Arduino Raw”. It supports IRremote, the old IRLib and Infrared4Arduino.
Examples for this library
The examples are available at File > Examples > Examples from Custom Libraries / IRremote.In order to fit the examples to the 8K flash of ATtiny85 and ATtiny88, the Arduino library ATtinySerialOut is required for this CPU’s.
SimpleReceiver + SimpleSender
The SimpleReceiver and SimpleSender examples are a good starting point. A simple example can be tested online with WOKWI.
TinyReceiver + TinySender
If code size or timer usage matters, look at these examples.The TinyReceiver example uses the TinyIRReceiver library which can only receive NEC, Extended NEC, ONKYO and FAST protocols, but does not require any timer. They use pin change interrupt for on the fly decoding, which is the reason for the restricted protocol choice.TinyReceiver can be tested online with WOKWI.
The TinySender example uses the TinyIRSender library which can only send NEC, ONKYO and FAST protocols.It sends NEC protocol codes in standard format with 8 bit address and 8 bit command as in SimpleSender example. It has options to send using Extended NEC, ONKYO and FAST protocols. Saves 780 bytes program memory and 26 bytes RAM compared to SimpleSender, which does the same, but uses the IRRemote library (and is therefore much more flexible).
SmallReceiver
If the protocol is not NEC and code size matters, look at this example.
ReceiveDemo + AllProtocolsOnLCD
ReceiveDemo receives all protocols and generates a beep with the Arduino tone() function on each packet received.Long press of one IR button (receiving of multiple repeats for one command) is detected.AllProtocolsOnLCD additionally displays the short result on a 1602 LCD. The LCD can be connected parallel or serial (I2C).By connecting debug pin to ground, you can force printing of the raw values for each frame. The pin number of the debug pin is printed during setup, because it depends on board and LCD connection type.This example also serves as an example how to use IRremote and tone() together.
ReceiveDump
Receives all protocols and dumps the received signal in different flavors including Pronto format. Since the printing takes much time, repeat signals may be skipped or interpreted as UNKNOWN.
SendDemo
Sends all available protocols at least once.
SendAndReceive
Demonstrates receiving while sending.
ReceiveAndSend
Record and play back last received IR signal at button press. IR frames of known protocols are sent by the approriate protocol encoder.
UNKNOWN
protocol frames are stored as raw data and sent with
sendRaw()
.
ReceiveAndSendDistanceWidth
Try to decode each IR frame with the universal DistanceWidth decoder, store the data and send it on button press with
sendPulseDistanceWidthFromArray()
.Storing data for distance width protocol requires 17 bytes. The ReceiveAndSend example requires 16 bytes for known protocol data and 37 bytes for raw data of e.g.NEC protocol.
ReceiveOneAndSendMultiple
Serves as a IR remote macro expander. Receives Samsung32 protocol and on receiving a specified input frame, it sends multiple Samsung32 frames with appropriate delays in between. This serves as a Netflix-key emulation for my old Samsung H5273 TV.
IRDispatcherDemo
Framework for calling different functions of your program for different IR codes.
IRrelay
Control a relay (connected to an output pin) with your remote.
IRremoteExtensionTest
Example for a user defined class, which itself uses the IRrecv class from IRremote.
SendLGAirConditionerDemo
Example for sending LG air conditioner IR codes controlled by Serial input.By just using the function
bool Aircondition_LG::sendCommandAndParameter(char aCommand, int aParameter)
you can control the air conditioner by any other command source.The file acLG.h contains the command documentation of the LG air conditioner IR protocol. Based on reverse engineering of the LG AKB73315611 remote.IReceiverTimingAnalysis can be tested online with WOKWI Click on the receiver while simulation is running to specify individual IR codes.
ReceiverTimingAnalysis
This example analyzes the signal delivered by your IR receiver module.
Values can be used to determine the stability of the received signal as well as a hint for determining the protocol.It also computes the
MARK_EXCESS_MICROS
value, which is the extension of the mark (pulse) duration introduced by the IR receiver module.It can be tested online with WOKWI. Click on the receiver while simulation is running to specify individual NEC IR codes.
UnitTest
ReceiveDemo + SendDemo in one program. Demonstrates receiving while sending.
Here you see the delay of the receiver output (blue) from the IR diode input (yellow).
WOKWI online examples
- Simple receiver
- Simple toggle by IR key 5
- TinyReceiver
- ReceiverTimingAnalysis
- Receiver with LCD output and switch statement
Issues and discussions
- Do not open an issue without first testing some of the examples!
- If you have a problem, please post the MCVE (Minimal Complete Verifiable Example) showing this problem. My experience is, that most of the times you will find the problem while creating this MCVE 😄.
- Use code blocks; it helps us help you when we can read your code!
Compile options / macros for this library
To customize the library to different requirements, there are some compile options / macros available.These macros must be defined in your program before the line
#include
to take effect.Modify them by enabling / disabling them, or change the values if applicable.
Name | Default value | Description |
100 | Buffer size of raw input buffer. Must be even! 100 is sufficient for regular protocols of up to 48 bits, but for most air conditioner protocols a value of up to 750 is required. Use the ReceiveDump example to find smallest value for your requirements. | |
disabled | Excludes the universal decoder for pulse distance protocols and decodeHash (special decoder for all protocols) from | |
all | Selection of individual protocol(s) to be decoded. You can specify multiple protocols. See here | |
disabled | Check for additional required characteristics of protocol timing like length of mark for a constant mark protocol, where space length determines the bit value. Requires up to 194 additional bytes of program memory. | |
disabled | Saves up to 60 bytes of program memory and 2 bytes RAM. | |
20 | MARK_EXCESS_MICROS is subtracted from all marks and added to all spaces before decoding, to compensate for the signal forming of different IR receiver modules. | |
5000 |
Minimum gap between IR transmissions, to detect the end of a protocol.
Must be greater than any space of a protocol e.g. the NEC header space of 4500 µs. Must be smaller than any gap between a command and a repeat; e.g. the retransmission gap for Sony is around 24 ms. Keep in mind, that this is the delay between the end of the received command and the start of decoding. |
|
disabled | Enable it if you use a RF receiver, which has an active HIGH output signal. | |
disabled | If specified, it reduces program size and improves send timing for AVR. If you want to use a variable to specify send pin e.g. with | |
disabled | Disables carrier PWM generation in software and use hardware PWM (by timer). Has the advantage of more exact PWM generation, especially the duty cycle (which is not very relevant for most IR receiver circuits), and the disadvantage of using a hardware timer, which in turn is not available for other libraries and to fix the send pin (but not the receive pin) at the dedicated timer output pin(s). Is enabled for ESP32 and RP2040 in all examples, since they support PWM gereration for each pin without using a shared resource (timer). | |
disabled | Uses no carrier PWM, just simulate an active low receiver signal. Used for transferring signal by cable instead of IR. Overrides | |
30 | Duty cycle of IR send signal. | |
disabled | Uses or simulates open drain output mode at send pin. Attention, active state of open drain is LOW, so connect the send LED between positive supply and send pin! | |
disabled | Saves up to 450 bytes program memory and 269 bytes RAM if receiving functionality is not required. | |
disabled | Excludes BANG_OLUFSEN, BOSEWAVE, WHYNTER, FAST and LEGO_PF from | |
disabled | Required on some boards (like my BluePill and my ESP8266 board), where the feedback LED is active low. | |
disabled | Disables the LED feedback code for send and receive. Saves around 100 bytes program memory for receiving, around 500 bytes for sending and halving the receiver ISR (Interrupt Service Routine) processing time. | |
50 | Resolution of the raw input buffer data. Corresponds to 2 pulses of each 26.3 µs at 38 kHz. | |
25 | Relative tolerance (in percent) for matchTicks(), matchMark() and matchSpace() functions used for protocol decoding. | |
disabled | Enables lots of lovely debug output. | |
Selection of timer to be used for generating IR receiving sample interval. |
These next macros for TinyIRReceiver must be defined in your program before the line
#include
to take effect.
Name | Default value | Description |
The pin number for TinyIRReceiver IR input, which gets compiled in. | ||
The pin number for TinyIRReceiver feedback LED, which gets compiled in. | ||
disabled | Disables the feedback LED function. Saves 14 bytes program memory. | |
disabled | Disables the addres and command parity checks. Saves 48 bytes program memory. | |
disabled | Like NEC, but take the 16 bit address as one 16 bit value and not as 8 bit normal and 8 bit inverted value. | |
disabled | Like NEC, but take the 16 bit address and command each as one 16 bit value and not as 8 bit normal and 8 bit inverted value. | |
disabled | Use FAST protocol (no address and 16 bit data, interpreted as 8 bit command and 8 bit inverted command) instead of NEC. | |
disabled | Instead of sending / receiving the NEC special repeat code, send / receive the original frame for repeat. | |
disabled | Call the fixed function |
The next macro for IRCommandDispatcher must be defined in your program before the line
#include
to take effect.
|
USE_TINY_IR_RECEIVER
| disabled | Use TinyReceiver for receiving IR codes. |
|
IR_COMMAND_HAS_MORE_THAN_8_BIT
| disabled | Enables mapping and dispatching of IR commands consisting of more than 8 bits. Saves up to 160 bytes program memory and 4 bytes RAM + 1 byte RAM per mapping entry. |
|
BUZZER_PIN
| | If
USE_TINY_IR_RECEIVER
is enabled, the pin to be used for the optional 50 ms buzzer feedback before executing a command. Other IR libraries than Tiny are not compatible with tone() command. |
Changing include (*.h) files with Arduino IDE
First, use Sketch > Show Sketch Folder (Ctrl+K).If you have not yet saved the example as your own sketch, then you are instantly in the right library folder.Otherwise you have to navigate to the parallel
libraries
folder and select the library you want to access.In both cases the library source and include files are located in the libraries
src
directory.The modification must be renewed for each new library version!
Modifying compile options / macros with PlatformIO
If you are using PlatformIO, you can define the macros in the platformio.ini file with
build_flags = -D MACRO_NAME
or
build_flags = -D MACRO_NAME=macroValue
.
Modifying compile options / macros with Sloeber IDE
If you are using Sloeber as your IDE, you can easily define global symbols with Properties > Arduino > CompileOptions.
Supported Boards
Issues and discussions with the content “Is it possible to use this library with the ATTinyXYZ? / board XYZ” without any reasonable explanations will be immediately closed without further notice.Digispark boards are only tested with ATTinyCore using
New Style
pin mapping for the Digispark Pro board.ATtiny boards are only tested with ATTinyCore or megaTinyCore.
- Arduino Uno / Mega / Leonardo / Duemilanove / Diecimila / LilyPad / Mini / Fio / Nano etc.
-
Arduino Uno R4, but not yet tested, because of lack of a R4 board. Sending does not work on the
arduino:renesas_uno:unor4wifi
. - Teensy 1.0 / 1.0++ / 2.0 / 2++ / 3.0 / 3.1 / 3.2 / Teensy-LC – but limited support; Credits: PaulStoffregen (Teensy Team)
- Sanguino
- ATmega8, 48, 88, 168, 328
- ATmega8535, 16, 32, 164, 324, 644, 1284,
- ATmega64, 128
- ATmega4809 (Nano every)
- ATtiny3217 (Tiny Core 32 Dev Board)
- ATtiny84, 85, 167 (Digispark + Digispark Pro)
- SAMD21 (Zero, MKR*, but not SAMD51 and not DUE, the latter is SAM architecture)
- ESP8266
- ESP32 (ESP32-C3 since board package 2.0.2 from Espressif) not for ESP32 core version > 3.0.0
- Sparkfun Pro Micro
- Nano Every, Uno WiFi Rev2, nRF5 BBC MicroBit, Nano33_BLE
- BluePill with STM32
- RP2040 based boards (Raspberry Pi Pico, Nano RP2040 Connect etc.)
For ESP8266/ESP32, this library supports an impressive set of protocols and a lot of air conditioners
We are open to suggestions for adding support to new boards, however we highly recommend you contact your supplier first and ask them to provide support from their side.If you can provide examples of using a periodic timer for interrupts for the new board, and the board name for selection in the Arduino IDE, then you have way better chances to get your board supported by IRremote.
Timer and pin usage
The receiver sample interval of 50 µs is generated by a timer. On many boards this must be a hardware timer. On some boards where a software timer is available, the software timer is used.
Every pin can be used for receiving.If software PWM is selected, which is default, every pin can also be used for sending. Sending with software PWM does not require a timer!
The TinyReceiver example uses the TinyReceiver library, which can only receive NEC codes, but does not require any timer and runs even on a 1 MHz ATtiny85.
The code for the timer and the timer selection is located in private/IRTimer.hpp. The selected timer can be adjusted here.
Be aware that the hardware timer used for receiving should not be used for analogWrite()!.
Board/CPU |
Receive
& send PWM Timer Default timer is bold |
Hardware-Send-PWM Pin |
analogWrite()
pins occupied by timer |
ATtiny84 | |||
ATtiny85 > 4 MHz | 0, 1 | 0, 4 | 0, 1 & 4 |
ATtiny88 > 4 MHz | PB1 / 8 | PB1 / 8 & PB2 / 9 | |
ATtiny167 > 4 MHz | 9, 8 – 15 | 8 – 15 | |
ATtiny1604 | TCB0 | PA05 | |
ATtiny1614, ATtiny816 | TCA0 | PA3 | |
ATtiny3217 | TCA0, TCD | ||
ATmega8 | |||
ATmega1284 | 1, 2, 3 | 13, 14, 6 | |
ATmega164, ATmega324, ATmega644 | 1, 2 | 13, 14 | |
ATmega8535 ATmega16, ATmega32 | 13 | ||
ATmega64, ATmega128, ATmega1281, ATmega2561 | 13 | ||
ATmega8515, ATmega162 | 13 | ||
ATmega168, ATmega328 | 1, 2 | 9, 3 | 9 & 10, 3 & 11 |
ATmega1280, ATmega2560 | 1, 2, 3, 4, 5 | 5, 6, 9, 11, 46 | 5, 6, 9, 11, 46 |
ATmega4809 | TCB0 | A4 | |
Leonardo (Atmega32u4) | 1, 3, 4_HS | 5, 9, 13 | 5, 9, 13 |
Zero (SAMD) | TC3 | *, 9 | |
ESP32 | Ledc chan. 0 | All pins | |
Sparkfun Pro Micro | 1, 3 | 5, 9 | |
Teensy 1.0 | 17 | 15, 18 | |
Teensy 2.0 | 1, 3, 4_HS | 9, 10, 14 | 12 |
Teensy++ 1.0 / 2.0 | 1, 2, 3 | 1, 16, 25 | |
Teensy-LC | TPM1 | 16 | 17 |
Teensy 3.0 – 3.6 | CMT | ||
Teensy 4.0 – 4.1 | FlexPWM1.3 | 7, 25 | |
BluePill / STM32F103C8T6 | PA6 & PA7 & PB0 & PB1 | ||
BluePill / STM32F103C8T6 | TIM4 | PB6 & PB7 & PB8 & PB9 | |
RP2040 / Pi Pico | default alarm pool | All pins | No pin |
RP2040 / Mbed based | Mbed Ticker | All pins | No pin |
No timer required for sending
The send PWM signal is by default generated by software. Therefore every pin can be used for sending.
The PWM pulse length is guaranteed to be constant by using
delayMicroseconds()
.
Take care not to generate interrupts during sending with software generated PWM, otherwise you will get jitter in the generated PWM.
E.g. wait for a former
Serial.print()
statement to be finished by
Serial.flush()
.
Since the Arduino
micros()
function has a resolution of 4 µs at 16 MHz, we always see a small jitter in the signal, which seems to be OK for the receivers.
Software generated PWM showing small jitter because of the limited resolution of 4 µs of the Arduino core | Detail (ATmega328 generated) showing 30% duty cycle |
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