Hi everyone! I’d appreciate any insights, corrections, or observations regarding this issue:
Project: Bidirectional communication using NRF24L01 (PA+LNA) between a MASTER (Arduino Mega) and two independent Slaves (Arduino UNO and MEGA).
Problem: The MASTER successfully sends messages to both Slaves, and both receive them correctly. However, while Slave UNO replies successfully, Slave MEGA fails to send a reply back to the Master.
I suspect the issue might lie in the Channel and Pipe configuration. To rule out overlapping issues, I disconnected Slave UNO (which works fine), but Slave MEGA still couldn’t send a reply back to the Master.
Thanks in advance!
SCHEMATIC (Mega + NRF24L01):
SCHEMATIC (UNO + NRF24L01):
SERIAL PORT DISPLAY
Master Serial display:
Slave Mega Serial display:
Slave UNO Serial display:
Only Master and Slave Mega (no Slave UNO) Serial display:
MASTER CODE:
#include <SPI.h>
#include <nRF24L01.h>
#include <RF24.h>
RF24 radio(7, 8); // CE, CSN
const byte addresses[4][6] = {"00001", "00002", "00003", "00004"};
// addresses[0] = "00001"; MASTER -> SLAVE UNO
// addresses[1] = "00002"; MASTER -> SLAVE MEGA
// addresses[2] = "00003"; SLAVE UNO -> MEGA
// addresses[3] = "00004"; SLAVE MEGA -> MEGA
void setup() {
Serial.begin(9600);
radio.begin();
radio.setPALevel(RF24_PA_MIN);
radio.openWritingPipe(addresses[0]); // To send message to SLAVE UNO (channel 00001)
radio.openWritingPipe(addresses[1]); // To send message to SLAVE MEGA (channel 00002)
radio.openReadingPipe(1, addresses[2]); // To receive reply from SLAVE UNO (channel 00003)
radio.openReadingPipe(2, addresses[3]); // To receive reply from SLAVE MEGA (channel 00004)
}
void loop() {
const char message[] = "Message from MASTER";
//SEND MESSAGE TO SLAVE UNO------------------------------------------------------------
radio.stopListening();
radio.openWritingPipe(addresses[0]); // To send message to SLAVE UNO (channel 00001)
if (radio.write(&message, sizeof(message))) { //Confirm if message was sent
Serial.println("Message sent to SLAVE UNO");
} else {
Serial.println("Failed messaging to SLAVE UNO");
}
//RECEIVE REPLY FROM SLAVE UNO---------------------------------------------------------
radio.startListening();
//Verify if a reply has been received
unsigned long startTime = millis();
bool receivedReply = false;
while (millis() - startTime < 1000) { //Wait 1sec to receive reply
if (radio.available()) {
char replyFromSlaveUNO[32] = "";
radio.read(&replyFromSlaveUNO, sizeof(replyFromSlaveUNO));
Serial.println(replyFromSlaveUNO);
receivedReply = true;
break;
}
}
if (!receivedReply) {
Serial.println("No reply from SLAVE UNO");
}
//SEND MESSAGE TO SLAVE MEGA-----------------------------------------------------------
radio.stopListening();
radio.openWritingPipe(addresses[1]); // To send message to SLAVE MEGA (channel 00002)
if (radio.write(&message, sizeof(message))) { //Confirm if message was sent
Serial.println("Message sent to SLAVE MEGA");
} else {
Serial.println("Failed messaging to SLAVE MEGA");
}
//RECEIVE REPLY FROM SLAVE MEGA--------------------------------------------------------
radio.startListening();
//Verify if a reply has been received
startTime = millis();
receivedReply = false;
while (millis() - startTime < 1000) { //Wait 1sec to receive reply
if (radio.available()) {
char replyFromSlaveMEGA[32] = "";
radio.read(&replyFromSlaveMEGA, sizeof(replyFromSlaveMEGA));
Serial.println(replyFromSlaveMEGA);
receivedReply = true;
break;
}
}
if (!receivedReply) {
Serial.println("No reply from SLAVE MEGA.");
}
delay(1000);
}
SLAVE MEGA:
#include <SPI.h>
#include <nRF24L01.h>
#include <RF24.h>
RF24 radio(7, 8); // CE, CSN
const byte addresses[4][6] = {"00001", "00002", "00003", "00004"};
void setup() {
Serial.begin(9600);
radio.begin();
radio.setPALevel(RF24_PA_MIN);
radio.openReadingPipe(1, addresses[1]); // Receive from MASTER (channel 00002)
radio.openWritingPipe(addresses[3]); // Send to MASTER (channel 00004)
}
void loop() {
radio.startListening();
//RECEIVE FROM MASTER
if (radio.available()) {
char receivedMessage[32] = "";
radio.read(&receivedMessage, sizeof(receivedMessage));
Serial.println(receivedMessage); //Confirm message received from MASTER
//REPLY TO MASTER
radio.stopListening();
const char reply[] = "Reply from SLAVE MEGA";
if (radio.write(&reply, sizeof(reply))) { //Confirm if reply was sent to MASTER
Serial.println("Reply sent to MASTER");
} else {
Serial.println("No reply sent to MASTER");
}
}
}
SLAVE UNO:
#include <SPI.h>
#include <nRF24L01.h>
#include <RF24.h>
RF24 radio(7, 8); // CE, CSN
const byte addresses[4][6] = {"00001", "00002", "00003", "00004"};
void setup() {
Serial.begin(9600);
radio.begin();
radio.setPALevel(RF24_PA_MIN);
// Configurar lectura y escritura
radio.openReadingPipe(1, addresses[0]); // Receive from MASTER (channel 00001)
radio.openWritingPipe(addresses[2]); // Send to MASTER (channel 00003)
}
void loop() {
radio.startListening();
//RECEIVE FROM MASTER
if (radio.available()) {
char receivedMessage[32] = "";
radio.read(&receivedMessage, sizeof(receivedMessage));
Serial.println(receivedMessage); //Confirm message received from MASTER
//REPLY TO MASTER
radio.stopListening();
const char reply[] = "Reply from SLAVE UNO";
if (radio.write(&reply, sizeof(reply))) { //Confirm if reply was sent to MASTER
Serial.println("Reply sent to MASTER");
} else {
Serial.println("No reply sent to MASTER");
}
}
}
