NRF24L01-Based Button State Transmission and Receiver System

Components Required

1. Arduino Nano – 2 units
2. NRF24L01 Module – 2 units
3. Push Button – 1 unit
4. LED – 1 unit
5. 220Ω Resistor – 1 unit
6. Breadboard and jumper wires

How It Works

• Transmitter: Sends the push button’s state (HIGH/LOW).
• Receiver: Receives the transmitted data and displays the state using an LED.

Circuit Diagram

Transmitter:

• NRF24L01 Connections:
  • VCC → Arduino 3.3V
  • GND → Arduino GND
  • CE → Pin 9
  • CSN → Pin 10
  • SCK → Pin 13
  • MOSI → Pin 11
  • MISO → Pin 12
• Button Connection:
  • One terminal → Pin 2
  • Other terminal → GND (with pull-down resistor)

Receiver:

• NRF24L01 Connections:
  • VCC → Arduino 3.3V
  • GND → Arduino GND
  • CE → Pin 9
  • CSN → Pin 10
  • SCK → Pin 13
  • MOSI → Pin 11
  • MISO → Pin 12
• LED Connection:
  • Anode → Pin 3 (via resistor)
  • Cathode → GND

Code

Transmitter Code

#include <SPI.h>
#include <nRF24L01.h>
#include <RF24.h>

RF24 radio(9, 10);  // CE, CSN pins
const byte address[6] = "00001";  // Communication address
int button_pin = 2;  // Button pin
boolean button_state = 0;

void setup() 
{
  pinMode(button_pin, INPUT);
  radio.begin();
  radio.openWritingPipe(address);
  radio.setPALevel(RF24_PA_MIN);
  radio.stopListening();
}

void loop()
{
  button_state = digitalRead(button_pin);
  if (button_state == HIGH)
  {
    const char text[] = "Your Button State is HIGH";
    radio.write(&text, sizeof(text));                
  }
  else
  {
    const char text[] = "Your Button State is LOW";
    radio.write(&text, sizeof(text)); 
  }
  delay(1000);
}

Receiver Code

#include <SPI.h>
#include <nRF24L01.h>
#include <RF24.h>

RF24 radio(9, 10);  // CE, CSN pins
const byte address[6] = "00001";  // Communication address
int led_pin = 3;  // LED pin
boolean button_state;

void setup() 
{
  pinMode(led_pin, OUTPUT);
  radio.begin();
  radio.openReadingPipe(0, address);
  radio.setPALevel(RF24_PA_MIN);
  radio.startListening();
}

void loop()
{
  if (radio.available())
  {
    radio.read(&button_state, sizeof(button_state));
    if (button_state == HIGH)
    {
      digitalWrite(led_pin, HIGH);  // Turn LED ON
    }
    else
    {
      digitalWrite(led_pin, LOW);  // Turn LED OFF
    }
  }
}

Step-by-Step Setup

1. Hardware Setup

1. Transmitter: Connect the button and NRF24L01 module as per the diagram.
2. Receiver: Connect the LED and NRF24L01 module.
3. Make sure all pin connections are accurate as shown in the diagram.

2. Software Setup

1. Open Arduino IDE.
2. Install RF24 Library:
   • Go to Sketch > Include Library > Manage Libraries, search for “RF24,” and install it.
3. Upload the transmitter code to one Arduino board.
4. Upload the receiver code to the other Arduino board.

3. Power and Testing

1. Provide 3.3V power to both Arduino boards.
2. Press the push button and observe the LED’s behavior on the receiver.
3. Check the transmitted messages on the Serial Monitor if needed.

Range and Notes

• Range: Standard NRF24L01 modules have a range of 20–30 meters indoors. Using the NRF24L01-PA-LNA module with an antenna can extend the range to over 1 kilometer (outdoors).
• Ensure the module is powered at 3.3V as it cannot handle 5V.
• For stable communication, place the modules where signal interference is minimal.

This project is highly suitable for remote control systems, robotics, and home automation applications.

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Robotics Lab

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