Hi everyone! 
I'm experiencing difficulties sending both plain text and concatenated text messages in a bidirectional communication setup between NRF24L01 modules. I would greatly appreciate any guidance you could provide, as I'm unable to find relevant references.
Project:
Transmitter contains the push buttons and Receiver contains 2 pumps and 2 temperature sensors (DS18B20). Button1 controls Pump1, Button2 controls Pump2, and Button3 controls two DS18B20.
(1) The NFR24L01 TRANSMITTER detects the pressed buttons and sends the array "Message1" to the NFR24L01 RECEIVER to execute an action.
(2) The NFR24L01 RECEIVER executes the action and sends back the array "Message2" to the NFR24L01 TRANSMITTER.
Issue
Pertains to (2). I'm unable to figure out how to send "Message2" and receive it. I have indicated the issue where I comment 'HERE IS MY ISSUE'.` What's odd is that when I print the messages for testing in the Serial Monitor of the receiver (COM3), it displays correctly. But in the transmitter (COM4), I get a '⸮⸮⸮⸮⸮#e⸮⸮'. I expect to receive on COM4 what is on COM3.
CODES
//NFR24L01 TRANSMITTER CODE
#include <SPI.h>
#include <nRF24L01.h>
#include <RF24.h>
//PINS------------------------------------------------------------------------------------------------------------------------
// NRF24L01 Pins
RF24 radio(7, 8); // CE, CSN
const byte address[][10] = {"00001","00002"};//addresses that receives and transfer data
// Pump Pins
const int pinPushButton1 = 22; //Controls Pump1
const int pinPushButton2 = 23; //Controls Pump2
// DS18B20 Pins
const int pinPushButton3 = 24; //Controls DS18B20
//VARIABLES------------------------------------------------------------------------------------------------------------------------
// NRF24L01 Variables
int Message1[3];
String Message2[4];
//MAIN------------------------------------------------------------------------------------------------------------------------
void setup() {
pinMode(pinPushButton1, INPUT_PULLUP); // Pump1 - Enable internal pull-up resistor for button
pinMode(pinPushButton2, INPUT_PULLUP); // Pump2 - Enable internal pull-up resistor for button
pinMode(pinPushButton3, INPUT_PULLUP); // DS18B20
Serial.begin(9600);
radio.begin();
radio.openWritingPipe(address[0]);//address of transmitter
radio.openReadingPipe(1, address[1]);//address of receiver - specify the ch-freq in which receives
radio.setPALevel(RF24_PA_MAX);//set power amplifier level (minimum since NRFs are close)
}
void loop() {
delay(10);
radio.stopListening(); //transmit
Message1[0] = digitalRead(pinPushButton1); // Pump1 button current state
Message1[1] = digitalRead(pinPushButton2); // Pump2 button current state
Message1[2] = digitalRead(pinPushButton3); // DS18B20
radio.write(Message1, sizeof(Message1));
delay(10);
//HERE IS MY ISSUE
radio.startListening(); //receive
if (radio.available())
{
radio.read(Message2, sizeof(Message2));
Serial.println(Message2[0]);
Serial.println(Message2[1]);
Serial.println(Message2[2]);
}
}
// NFR24L01 RECEIVER CODE
#include <SPI.h>
#include <nRF24L01.h>
#include <RF24.h>
#include <OneWire.h>
#include <DallasTemperature.h>
//PINS------------------------------------------------------------------------------------------------------------------------
// NFR24L01 Pins
RF24 radio(7, 8); // CE, CSN
const byte address[][10] = {"00001","00002"};//addresses that receives and transfer data
// Pump Pins
const int pinRelay1 = 9;
const int pinRelay2 = 10;
// DS18B20 Pins
#define ONE_WIRE_BUS 25 // Data wire is plugged into pin 25 on the Arduino
//VARIABLES------------------------------------------------------------------------------------------------------------------------
// NRF24L01 Variables
int Message1[3];
String Message2[4];
// Pump Variables
bool previousButtonState1 = HIGH; // Variable to store the previous state of the button. Initially high (not pressed)
bool previousButtonState2 = HIGH; // Variable to store the previous state of the button. Initially high (not pressed)
bool printedState = false; // Flag to control the printing of the state
enum State1 {OFF1,ON1}; // States of Pump1
enum State2 {OFF2,ON2}; // States of Pump2
State1 state1 = OFF1;
State2 state2 = OFF2;
State1 previousState1 = OFF1;
State2 previousState2 = OFF2;
// DS18B20 Variables
enum State3 {OFF3, ON3};
State3 state3 = OFF3;
unsigned long lastDebounceTime = 0; // millisecond timestamp for last button press
const unsigned long debounceDelay = 200; // milliseconds
// DS18B20 Variables
int buttonState3; //button for temperature sensor DS18B20
//FUNCTIONS---------------------------------------------------------------------------------------------------------------------
// Pump Functions
void turnonPump1();
void turnoffPump1();
void turnonPump2();
void turnoffPump2();
// DS18B20 Functions
void readtemperature();
//OBJECTS------------------------------------------------------------------------------------------------------------------------
// DS18B20 Objects
OneWire oneWire(ONE_WIRE_BUS); // Setup a oneWire instance to communicate with any OneWire devices
DallasTemperature sensors(&oneWire); // Pass our oneWire reference to Dallas Temperature.
//MAIN------------------------------------------------------------------------------------------------------------------------
void setup() {
pinMode(pinRelay1, OUTPUT); // Initialize relay pin as output
pinMode(pinRelay2, OUTPUT); // Initialize relay pin as output
turnoffPump1();// Relay is initially off
turnoffPump2();// Relay is initially off
Serial.begin(9600);
radio.begin();
radio.openWritingPipe(address[1]);//address of transmitter
radio.openReadingPipe(1, address[0]);//address of receiver - specify the ch-freq in which receives
radio.setPALevel(RF24_PA_MAX);//set power amplifier level (minimum since NRFs are close)
sensors.begin(); // DS18B20
}
void loop() {
delay(10);
radio.startListening(); //receive
if (radio.available())
{
radio.read(Message1, sizeof(Message1));
int buttonState1 = Message1[0]; // Pump1 button current state
int buttonState2 = Message1[1]; // Pump2 button current state
int buttonState3 = Message1[2]; // DS18B20 button current state
// Pump1 Control
if (buttonState1 != previousButtonState1) { //Compare previous and current states of the button1
if (buttonState1 == LOW) { //keep the button1 activated
turnonPump1(); // Turn on Pump1
state1 = ON1;
} else {
turnoffPump1(); // Turn off Pump1
state1 = OFF1;
}
previousButtonState1 = buttonState1; // Update previous button state for button 1
}
// Pump2 Control
if (buttonState2 != previousButtonState2) { //Compare previous and current states of the button2
if (buttonState2 == LOW) { //keep the button2 activated
turnonPump2(); // Turn on Pump2
state2 = ON2;
} else {
turnoffPump2(); // Turn off Pump2
state2 = OFF2;
}
previousButtonState2 = buttonState2; // Update previous button state for button 2
}
delay(5);// Wait to avoid button bounces
// DS18B20 Control
if ((millis() - lastDebounceTime) > debounceDelay && buttonState3 == LOW) {
readtemperature(); //Read temperatures from DS18B20 sensors
state3 = ON3;
lastDebounceTime = millis(); // Update debounce timer
} else {
state3 = OFF3;
}
}
delay(10);
//HERE IS MY ISSUE
radio.stopListening(); //transmit
if (state1 != previousState1) { //Compare previous and current states of the button1
switch (state1) {
case OFF1:
Message2[0] = "PUMP 1 OFF";
radio.write(Message2, sizeof(Message2));
Serial.println(Message2[0]); //TEST
break;
case ON1:
Message2[0] = "PUMP 1 ON";
radio.write(Message2, sizeof(Message2));
Serial.println(Message2[0]); //TEST
break;
}
previousState1 = state1; //update state1
}
if (state2 != previousState2) { //Compare previous and current states of the button2
switch (state2) {
case OFF2:
Message2[1] = "PUMP 2 OFF";
radio.write(Message2, sizeof(Message2));
Serial.println(Message2[1]); //TEST
break;
case ON2:
Message2[1] = "PUMP 2 ON";
radio.write(Message2, sizeof(Message2));
Serial.println(Message2[1]); //TEST
break;
}
previousState2 = state2; //update state2
}
if (state3 == ON3) { //Compare previous and current states of the button3
Message2[2]="Temperatura 1: " + String(sensors.getTempCByIndex(0)); // Temperature from the sensor 1
Message2[3]="Temperatura 2: " + String(sensors.getTempCByIndex(1)); // Temperature from the sensor 2
radio.write(Message2, sizeof(Message2));
Serial.println(Message2[2]); //TEST
Serial.println(Message2[3]); //TEST
}
}
//FUNCTIONS------------------------------------------------------------------------------------------------------------------------
void turnonPump1() {
digitalWrite(pinRelay1, LOW);
}
void turnoffPump1() {
digitalWrite(pinRelay1, HIGH);
}
void turnonPump2() {
digitalWrite(pinRelay2, LOW);
}
void turnoffPump2() {
digitalWrite(pinRelay2, HIGH);
}
void readtemperature(){
sensors.requestTemperatures(); // Send the command to get temperatures
}
