NRF24L01 Radio Controlled Arduino Project

Arduino Code Example

Here is the code I used to control the receiver. Once you are ready, upload the code to the Receiver Arduino.

#include <SPI.h>
#include <RF24.h>
#include <Servo.h> 

#define CE_PIN 9
#define CSN_PIN 10

RF24 radio(CE_PIN, CSN_PIN);

#define myServo 3
Servo servo; 

// Motor Controller Pins
int EN1 = 5; 
int IN1 = 4;
int IN2 = 6;

struct JoystickData {
  int x;
  int y;
};

void setup() {
  Serial.begin(9600);
  
  // Initialize the NRF24 module
  if (!radio.begin()) {
    Serial.println("Failed to initialize NRF24 module. Please check wiring.");
    while (1); // Loop indefinitely if initialization fails
  }
  
  // Set the receiving address
  radio.openReadingPipe(1, 0xF0F0F0F0E1LL);
  
  // Start listening for incoming messages
  radio.startListening();

  // Attach servo to a PWM-capable pin, for example, pin 5
  servo.attach(myServo);

  // Motor driver pins setup
  pinMode(EN1, OUTPUT);
  pinMode(IN1, OUTPUT);
  pinMode(IN2, OUTPUT);
}

void loop() {
  // Check if there's a message available
  if (radio.available()) {
    JoystickData joystickData;
    
    // Read the message from the NRF24 module
    radio.read(&joystickData, sizeof(joystickData));
    
    // Print the received joystick data to the serial monitor
    Serial.print("Received Joystick Data - X: ");
    Serial.print(joystickData.x);
    Serial.print(", Y: ");
    Serial.println(joystickData.y);


    // Control the DC motor based on X axis
    int motorSpeed = map(joystickData.x, 0, 1023, -255, 255); // Map joystick data to motor speed
    analogWrite(EN1, abs(motorSpeed)); // Control the motor speed
    if (motorSpeed > 50) {
      Serial.println("Motor Forwards");
      digitalWrite(IN1, HIGH); // Set motor direction
      digitalWrite(IN2, LOW);
    } else if (motorSpeed < -50) {
      Serial.println("Motor Backwards");
      digitalWrite(IN1, LOW); // Set motor direction
      digitalWrite(IN2, HIGH);
    } else{
      Serial.println("Motor Standby");
      digitalWrite(IN1, LOW); // Motor off
      digitalWrite(IN2, LOW);
    }


    // Control the servo based on Y axis
    int servoAngle = map(joystickData.y, 0, 1023, 0, 180); // Map joystick data to servo angle
    servo.write(servoAngle); // Set servo angle
  }
}

Breaking Down the Code

Now, let’s break down the receiver code step by step:

Step 1: Include Libraries

#include <SPI.h>
#include <RF24.h>
#include <Servo.h>

These lines include the necessary libraries for SPI communication, the NRF24L01 module, and servo control.

Step 2: Define Pins

#define CE_PIN 9
#define CSN_PIN 10

These lines define the pins used for the CE (Chip Enable) and CSN (Chip Select Not) of the NRF24L01 module.

Step 3: Create RF24 Object

RF24 radio(CE_PIN, CSN_PIN);

This line creates an instance of the RF24 class with the specified CE and CSN pins.

Step 4: Define Servo Pin

#define myServo 3

This line defines the pin used to control the servo motor.

Step 5: Create the Servo Object

Servo servo;

This line declares a Servo object named servo to control the servo motor.

Step 6: Define Motor Controller Pins

int EN1 = 5; 
int IN1 = 4;
int IN2 = 6;

These lines define the pins used to control the DC motor connected to the motor controller.

Step 7: Define JoystickData Structure

struct JoystickData {
int x;
int y;
};

This defines a structure named JoystickData containing two integer variables for x and y joystick values.

Step 8: Setup Function

void setup() {
  Serial.begin(9600);
  
  // Initialize the NRF24 module
  if (!radio.begin()) {
    Serial.println("Failed to initialize NRF24 module. Please check wiring.");
    while (1); // Loop indefinitely if initialization fails
  }
  
  // Set the receiving address
  radio.openReadingPipe(1, 0xF0F0F0F0E1LL);
  
  // Start listening for incoming messages
  radio.startListening();

  // Attach servo to a PWM-capable pin
  servo.attach(myServo);

  // Motor driver pins setup
  pinMode(EN1, OUTPUT);
  pinMode(IN1, OUTPUT);
  pinMode(IN2, OUTPUT);
}

In the setup function:

• Serial communication is initialized at a baud rate of 9600.
• The NRF24 module is initialized, and if initialization fails, an error message is printed.
• The receiving address for the NRF24 module is set.
• The NRF24 module starts listening for incoming messages.
• The servo is attached to the specified pin, and motor controller pins are configured as outputs.

Step 9: Loop Function

void loop() {
  // Check if there's a message available
  if (radio.available()) {
    JoystickData joystickData;
    
    // Read the message from the NRF24 module
    radio.read(&joystickData, sizeof(joystickData));
    
    // Print the received joystick data to the serial monitor
    Serial.print("Received Joystick Data - X: ");
    Serial.print(joystickData.x);
    Serial.print(", Y: ");
    Serial.println(joystickData.y);

    // Control the DC motor based on X axis
    int motorSpeed = map(joystickData.x, 0, 1023, -255, 255); // Map joystick data to motor speed
    analogWrite(EN1, abs(motorSpeed)); // Control the motor speed
    if (motorSpeed > 50) {
      Serial.println("Motor Forwards");
      digitalWrite(IN1, HIGH); // Set motor direction
      digitalWrite(IN2, LOW);
    } else if (motorSpeed < -50) {
      Serial.println("Motor Backwards");
      digitalWrite(IN1, LOW); // Set motor direction
      digitalWrite(IN2, HIGH);
    } else {
      Serial.println("Motor Standby");
      digitalWrite(IN1, LOW); // Motor off
      digitalWrite(IN2, LOW);
    }

    // Control the servo based on Y axis
    int servoAngle = map(joystickData.y, 0, 1023, 0, 180); // Map joystick data to servo angle
    servo.write(servoAngle); // Set servo angle
  }
}

In the loop function:

• It checks if there’s a message available from the NRF24 module.
• If a message is available, it reads the joystick data into the joystickData variable.
• It prints the received joystick data to the Serial monitor.
• It maps the joystick data to control the speed and direction of the DC motor.
• Based on the mapped motor speed, it sets the direction of the motor using the motor controller pins.
• It also maps the joystick data to control the angle of the servo motor.