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6.4 Using an Infrared Remote Control

In this lesson, we’ll learn how to use an infrared (IR) remote control and an IR receiver with the Raspberry Pi Pico 2. This will allow us to receive and decode signals from an IR remote, enabling us to control our projects wirelessly.

What You’ll Need

In this project, we need the following components.

It’s definitely convenient to buy a whole kit, here’s the link:

Name

ITEMS IN THIS KIT

LINK

Newton Lab Kit

450+

Newton Lab Kit

You can also buy them separately from the links below.

SN

COMPONENT

QUANTITY

LINK

1

Raspberry Pi Pico 2

1

BUY

2

Micro USB Cable

1

3

Breadboard

1

BUY

4

Jumper Wires

Several

BUY

5

Infrared Receiver

1

BUY

Understanding Infrared Communication

Infrared communication involves transmitting data wirelessly using infrared light. Common household devices like TVs and DVD players use IR remote controls for operation.

  • IR Transmitter (Remote Control): Emits modulated infrared light when a button is pressed.

  • IR Receiver: Detects the modulated IR light and converts it into electrical signals that can be decoded.

Circuit Diagram

sch_irrecv

Wiring Diagram

wiring_irrecv

Writing the Code

We’ll write a program that initializes the IR receiver, listens for incoming IR signals, decodes them, and prints the corresponding button presses to the Serial Monitor.

Note

  • You can open the file 6.4_ir_remote_control.ino from newton-lab-kit/arduino/6.4_ir_remote_control.

  • Or copy this code into Arduino IDE.

  • Select the Raspberry Pi Pico 2 board and the correct port, then click “Upload”.

  • The IRremote library is used here, you can install it from the Library Manager.

    ../_images/lib_ir.png 
#define SEND_PWM_BY_TIMER

#include <IRremote.hpp>  // Include the IRremote library

const int receiverPin = 17;  // Define the pin number for the IR Sensor

void setup() {
  // Start serial communication at a baud rate of 115200
  Serial.begin(115200);
  // Initialize the IR receiver on the specified pin with LED feedback enabled
  IrReceiver.begin(receiverPin, ENABLE_LED_FEEDBACK);
}

void loop() {
  if (IrReceiver.decode()) {  // Check if the IR receiver has received a signal
    bool result = 0;
    String key = decodeKeyValue(IrReceiver.decodedIRData.command);
    if (key != "ERROR") {
      Serial.println(key);  // Print the readable command
      delay(100);
    }
  IrReceiver.resume();  // Prepare the IR receiver to receive the next signal
  }
}

// Function to map received IR signals to corresponding keys
String decodeKeyValue(long result) {
  switch (result) {
    case 0x45: return "POWER";
    case 0x47: return "MUTE";
    case 0x46: return "MODE";
    case 0x44: return "PLAY/PAUSE";
    case 0x40: return "BACKWARD";
    case 0x43: return "FORWARD";
    case 0x7: return "EQ";
    case 0x15: return "-";
    case 0x9: return "+";
    case 0x19: return "CYCLE";
    case 0xD: return "U/SD";
    case 0x16: return "0";
    case 0xC: return "1";
    case 0x18: return "2";
    case 0x5E: return "3";
    case 0x8: return "4";
    case 0x1C: return "5";
    case 0x5A: return "6";
    case 0x42: return "7";
    case 0x52: return "8";
    case 0x4A: return "9";
    case 0x0: return "ERROR";
    default: return "ERROR";
  }
}

After uploading the code, press buttons on the IR remote control. Observe the corresponding key labels printed in the Serial Monitor.

BACKWARD
CYCLE
POWER
MODE
EQ
5
9

Note

The new remote control may have a plastic piece at the end to isolate the battery. Pull out this plastic piece to activate the remote.

Understanding the Code

  1. Header and Constants:

    • #define SEND_PWM_BY_TIMER: This line appears to define a macro for sending PWM signals by using a timer. However, it is not used anywhere in the code, so it might be a leftover or a placeholder.

    • #include <IRremote.hpp>: Includes the IRremote library, which provides functionalities for sending and receiving IR signals.

    • const int receiverPin = 17;: Defines the pin (17) that the IR receiver module is connected to on the Arduino.

  2. Setup Function:

    • Serial.begin(115200);: Initializes serial communication at a baud rate of 115200, which allows the Arduino to communicate with a computer for debugging purposes.

    • IrReceiver.begin(receiverPin, ENABLE_LED_FEEDBACK);: Initializes the IR receiver on receiverPin and enables LED feedback, which will light up an LED when the IR receiver gets a signal.

    void setup() {
  Serial.begin(115200);
  IrReceiver.begin(receiverPin, ENABLE_LED_FEEDBACK);
}

  3. Loop Function:

    • if (IrReceiver.decode()): Checks if the IR receiver has received a valid IR signal. If it has, the function proceeds to decode it.

    • decodeKeyValue(IrReceiver.decodedIRData.command): Calls a function to convert the received IR command into a more human-readable key (like “POWER” or “MUTE”).

    • Serial.println(key);: Prints the decoded key to the serial monitor.

    • delay(100);: Adds a short delay to avoid printing the same signal multiple times.

    • IrReceiver.resume();: Prepares the IR receiver to receive the next signal by clearing the previous one.

    void loop() {
  if (IrReceiver.decode()) {
    bool result = 0;
    String key = decodeKeyValue(IrReceiver.decodedIRData.command);
    if (key != "ERROR") {
      Serial.println(key);
      delay(100);
    }
    IrReceiver.resume();
  }
}

  4. decodeKeyValue Function:

    • This function takes a long value result (the raw IR command) and uses a switch statement to map it to a specific key name. Each case corresponds to a different button on the remote.

    • For example, 0x45 maps to “POWER,” and 0x47 maps to “MUTE.”

    • If the command does not match any known key, the function returns “ERROR.”

    String decodeKeyValue(long result) {
  switch (result) {
    case 0x45: return "POWER";
    case 0x47: return "MUTE";
    case 0x46: return "MODE";
    ...
    case 0x4A: return "9";
    case 0x0: return "ERROR";
    default: return "ERROR";
  }
}

Troubleshooting

  • No Readings Displayed:

    • Ensure the IR receiver is properly connected to GPIO 17.

    • Verify that the IR receiver is receiving power (VCC and GND connections).

    • Check that the correct GPIO pin is defined in the code (receiverPin).

  • Incorrect Readings:

    • Confirm that the remote control is compatible with the IR receiver.

    • Check that the decodeKeyValue function correctly maps the IR codes from your specific remote.

    • Use a universal remote to ensure compatibility.

  • Unknown Commands:

    • Update the decodeKeyValue function to include the IR codes specific to your remote control.

    • Use an IR decoding tool or reference to find the correct codes emitted by your remote.

  • Signal Interference:

    • Ensure there are no obstructions between the remote and the IR receiver.

    • Avoid placing the sensor near other IR-emitting devices that might cause interference.

Further Exploration

  • Controlling Devices with IR Signals:

    Use decoded IR signals to control LEDs, motors, servos, or other actuators based on remote inputs.

  • Creating a Universal Remote:

    Expand the decodeKeyValue() function to support multiple remotes by mapping a broader range of IR codes.

  • Adding Feedback Mechanisms:

    Implement LCD or OLED displays to show the current state or received commands.

Conclusion

In this lesson, you’ve learned how to use an infrared (IR) remote control and an IR receiver with the Raspberry Pi Pico to receive and decode IR signals. By integrating the IRremote library, you can easily interpret remote control inputs and use them to interact with your projects wirelessly. This setup is foundational for creating remote-controlled devices, automated systems, and user-friendly interfaces in various applications.