Hello,
I am working on the following project as describes below.
- I have three nrf24l01modules
- I have connected each module with each Arduino uno board
- first nrf24l01 module is transmitter, second nrf24l01 module is extender and third nrf24l01 modules is receiver
- Now I have written a code in transmitter that if I connect pin2 with GND then the message should only go through extender module and send to the receiver.
- whenever receiver receives this message from extender the relay module connected to the receiver should ON, if the pin2 is disconnected on transmitter side then relay on receiver should be OFF. There should not be a direct connection between transmitter and receiver modules.
- If I disconnect the extender module then the receiver module should complain that no devices connected and transmitter should report that no devices connected.
- If transmitter off and both extender and receiver ON then the externder should display a message like no devices connected until sender connected.
- Need to have mechanism to check the device connectivity continuously without effecting the data sending by the transmitter throughout reciever.
I am having the following sketch for each module:
Extender:
#include <SPI.h>
#include <nRF24L01.h>
#include <RF24.h>
#define GREEN_LED 2 // LED for connection status
#define DATA_CHANNEL 110
RF24 radio(8, 9); // CE, CSN pins
// Addresses for communication
const uint64_t DATA_ADDRESS = 0xF0F0F0F0E1LL;
void setup() {
pinMode(GREEN_LED, OUTPUT);
digitalWrite(GREEN_LED, LOW); // Ensure LED is off initially
radio.begin();
radio.setPALevel(RF24_PA_LOW);
// Setup the data channel
radio.setChannel(DATA_CHANNEL);
radio.openReadingPipe(1, DATA_ADDRESS);
Serial.begin(9600);
radio.startListening(); // Start listening for messages
}
void loop() {
if (radio.available()) {
uint8_t pipeNum;
char receivedMessage[32] = "";
radio.read(&receivedMessage, sizeof(receivedMessage));
Serial.print("Received from Transmitter: ");
Serial.println(receivedMessage);
// Forward the message to the receiver
forwardData(receivedMessage);
}
}
void forwardData(const char* message) {
radio.stopListening(); // Stop listening to send data
// Create a new message with the "Extender:" prefix
char forwardedMessage[64] = "Extender:";
strcat(forwardedMessage, message); // Append the original message
// Ensure the string is null-terminated to avoid corruption
forwardedMessage[63] = '\0'; // Ensuring no overflow
// Debugging output: Display the forwarded message
Serial.print("Forwarding message: ");
Serial.println(forwardedMessage);
// Open the pipe to the receiver
radio.openWritingPipe(DATA_ADDRESS);
if (!radio.write(forwardedMessage, strlen(forwardedMessage) + 1)) {
Serial.println("Failed to forward message.");
} else {
Serial.println("Message forwarded successfully.");
}
radio.startListening(); // Start listening again
}
Transmitter:
#include <SPI.h>
#include <nRF24L01.h>
#include <RF24.h>
#define CONTROL_PIN 2 // Pin 2 for control functionality
#define GREEN_LED 4 // LED for connection status
#define DATA_CHANNEL 110
RF24 radio(8, 9);
// Addresses for communication
const uint64_t DATA_ADDRESS = 0xF0F0F0F0E1LL;
bool extenderPresent = false; // Assume no extender is present initially
void setup() {
pinMode(CONTROL_PIN, INPUT_PULLUP); // Control pin
pinMode(GREEN_LED, OUTPUT); // LED for connection status
radio.begin();
radio.setPALevel(RF24_PA_LOW);
// Setup the data channel
radio.setChannel(DATA_CHANNEL);
radio.openWritingPipe(DATA_ADDRESS);
Serial.begin(9600);
}
void loop() {
checkConnection();
const char* message;
if (digitalRead(CONTROL_PIN) == LOW) {
message = extenderPresent ? "Extender:SENDER:pin2connected" : "SENDER:pin2connected";
} else {
message = extenderPresent ? "Extender:SENDER:pin2disconnected" : "SENDER:pin2disconnected";
}
sendData(message); // Send regardless of extender presence for testing
// Blink LED if not connected
if (!radio.available()) {
blinkLed(GREEN_LED);
} else {
digitalWrite(GREEN_LED, HIGH); // Stay ON if connected
}
delay(100); // Adjust delay as necessary
}
void checkConnection() {
// Logic to update extenderPresent based on actual connection can be added here
}
void sendData(const char* message) {
Serial.print("Sending data message: ");
Serial.println(message);
radio.stopListening(); // Switch to send mode
if (!radio.write(message, strlen(message) + 1)) {
Serial.println("Failed to send data message.");
} else {
Serial.println("Data message sent successfully.");
}
radio.startListening(); // Return to listening mode
}
void blinkLed(int pin) {
digitalWrite(pin, LOW);
delay(100);
digitalWrite(pin, HIGH);
delay(100);
}
Receiver:
#include <SPI.h>
#include <nRF24L01.h>
#include <RF24.h>
// Define pins
#define RELAY_PIN 4 // Pin to control relay
#define RED_LED 2 // Red LED for extender connection
#define BLUE_LED 3 // Blue LED for direct sender connection
#define DATA_CHANNEL 110
RF24 radio(8, 9); // CE, CSN pins
// Addresses for communication
const uint64_t DATA_ADDRESS = 0xF0F0F0F0E1LL;
bool extenderPresent = false; // Track if the extender is connected
void setup() {
pinMode(RELAY_PIN, OUTPUT);
pinMode(RED_LED, OUTPUT);
pinMode(BLUE_LED, OUTPUT);
digitalWrite(RELAY_PIN, HIGH); // Ensure relay is OFF initially
digitalWrite(RED_LED, LOW); // Ensure RED LED is OFF
digitalWrite(BLUE_LED, LOW); // Ensure BLUE LED is OFF
Serial.begin(9600); // Start Serial for debugging
radio.begin();
radio.setPALevel(RF24_PA_LOW);
// Setup the data channel
radio.setChannel(DATA_CHANNEL);
radio.openReadingPipe(1, DATA_ADDRESS);
radio.startListening(); // Start listening for messages
}
void loop() {
handleDataMessage();
}
void handleDataMessage() {
uint8_t pipeNum;
while (radio.available(&pipeNum)) {
char receivedMessage[32] = "";
radio.read(&receivedMessage, sizeof(receivedMessage));
Serial.print("Received: ");
Serial.println(receivedMessage);
// Check for extender connection status
if (strstr(receivedMessage, "Extender:connected") != NULL) {
extenderPresent = true;
Serial.println("Extender is now connected.");
digitalWrite(RED_LED, HIGH); // Indicate extender is connected
digitalWrite(BLUE_LED, LOW); // Turn off blue LED
}
if (strstr(receivedMessage, "Extender:disconnected") != NULL) {
extenderPresent = false;
Serial.println("Extender is now disconnected.");
digitalWrite(RED_LED, LOW); // Turn off red LED
digitalWrite(BLUE_LED, LOW); // Turn off blue LED
}
// Handle messages based on extender presence
if (extenderPresent) {
if (strstr(receivedMessage, "Extender:") != NULL) {
if (strstr(receivedMessage, "pin2connected") != NULL) {
digitalWrite(RELAY_PIN, LOW); // Turn relay ON
Serial.println("Relay turned ON from Extender");
} else if (strstr(receivedMessage, "pin2disconnected") != NULL) {
digitalWrite(RELAY_PIN, HIGH); // Turn relay OFF
Serial.println("Relay turned OFF from Extender");
}
} else {
Serial.println("Message ignored as it was not from Extender.");
}
} else {
Serial.println("Extender not connected; ignoring messages.");
}
}
}
after executing these sketches, i found the weird behavior that the receiver always connects with transmitter though I connect or disconnect the extender module.
please help me how to resolve this. This is my wiring diagram whenever I press the button on transmitter the message should go though the extender to receiver.
Extender:
