3 buttons resulting in 3 different actions over nRF24L01

Using Arduino Programming Questions
1

Hello,

For my RC boat, I am using an Uno as my transmitter and ESP32 as my receiver. The idea is to have different modes of operation for the boat. On the transmitter side, I have 3 buttons, each connected to an LED to indicate what mode is active. I am using nRF24L01 for RF comms between the two. I'm struggling with the programming part. When the first button is pressed, I want to activate manual mode where joystick commands (x and y) are transmitted over to the receiver to influence a motor and a servo connected to the rudder. For the second mode, I'd like to have something like a heading hold mode where I can send a heading value through the serial monitor. I haven't yet decided what I want to do with the 3rd button but once I have an idea of how to successfully transmit and code this correctly, I'd like to have a 3rd functionality. The overall idea is that each LED will stay on as long as another button for a different mode is not selected. As of now, I can make the LEDs stay on but I am unable to command an output on the receiver's side. For the RF part, I have been going through tutorials and have been reading about sending data wirelessly using a struct format but I am relatively new to this so any guidance on that front would also be much appreciated. Thank you!

// Transmitter

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

#define BUTTON1 3
#define BUTTON2 4
#define BUTTON3 5
#define LED1 10
#define LED2 9
#define LED3 6

RF24 radio(7, 8); // CE, CSN pins for nRF24L01
const byte address[6] = "00001"; // Address for communication

bool button1State = false, button2State = false, button3State = false;
bool lastButton1 = false, lastButton2 = false, lastButton3 = false;
unsigned long debounceDelay = 50;
unsigned long lastDebounceTime1 = 0, lastDebounceTime2 = 0, lastDebounceTime3 = 0;

struct Payload {
  uint16_t mode; // 0: Manual, 1: Heading Hold, 2: Blink Mode
  uint16_t joystickX;
  uint16_t joystickY;
  uint16_t heading;
};

Payload data = {0, 0, 0, 0}; // Initial payload

void setup() {
  pinMode(BUTTON1, INPUT_PULLUP);
  pinMode(BUTTON2, INPUT_PULLUP);
  pinMode(BUTTON3, INPUT_PULLUP);
  pinMode(LED1, OUTPUT);
  pinMode(LED2, OUTPUT);
  pinMode(LED3, OUTPUT);

  radio.begin();
  radio.openWritingPipe(address);
  radio.setPALevel(RF24_PA_LOW);
  radio.stopListening();
}

void loop() {
  // Button 1
  if (digitalRead(BUTTON1) == LOW) {
    if (millis() - lastDebounceTime1 > debounceDelay) {
      button1State = !button1State;
      button2State = false;
      button3State = false;
      lastDebounceTime1 = millis();
    }
  }
  lastButton1 = digitalRead(BUTTON1);

  // Button 2
  if (digitalRead(BUTTON2) == LOW) {
    if (millis() - lastDebounceTime2 > debounceDelay) {
      button2State = !button2State;
      button1State = false;
      button3State = false;
      lastDebounceTime2 = millis();
    }
  }
  lastButton2 = digitalRead(BUTTON2);

  // Button 3
  if (digitalRead(BUTTON3) == LOW) {
    if (millis() - lastDebounceTime3 > debounceDelay) {
      button3State = !button3State;
      button1State = false;
      button2State = false;
      lastDebounceTime3 = millis();
    }
  }
  lastButton3 = digitalRead(BUTTON3);

  // Set LEDs and mode
  if (button1State) {
    digitalWrite(LED1, HIGH);
    digitalWrite(LED2, LOW);
    digitalWrite(LED3, LOW);
    data.mode = 0; // Manual Mode
    data.joystickX = analogRead(A0);
    data.joystickY = analogRead(A1);
  } else if (button2State) {
    digitalWrite(LED1, LOW);
    digitalWrite(LED2, HIGH);
    digitalWrite(LED3, LOW);
    data.mode = 1; // Heading Hold
    if (Serial.available()) {
      data.heading = Serial.parseInt(); // Read heading from Serial Monitor
    }
  } else if (button3State) {
    digitalWrite(LED1, LOW);
    digitalWrite(LED2, LOW);
    digitalWrite(LED3, HIGH);
    data.mode = 2; // Blink Mode
  }

  // Send data to receiver
  radio.write(&data, sizeof(data));
  delay(50);
}
2 

// Receiver

#include <SPI.h>
#include <nRF24L01.h>
#include <RF24.h>
#include <ESP32Servo.h>

#define BUILTIN_LED 2

const int servo1_pin = 14; // Servo pin

Servo servo1;

RF24 radio(4, 5); // CE, CSN pins for nRF24L01
const byte address[6] = "00001";

struct Payload {
  uint16_t mode; // 0: Manual, 1: Heading Hold, 2: Blink Mode
  uint16_t joystickX;
  uint16_t joystickY;
  uint16_t heading;
};

Payload data;

unsigned long lastBlinkTime = 0;
bool ledState = false;

void setup() {
  pinMode(BUILTIN_LED, OUTPUT);
  radio.begin();
  radio.openReadingPipe(0, address);
  radio.setPALevel(RF24_PA_LOW);
  radio.startListening();
}

void loop() {
  if (radio.available()) {
    radio.read(&data, sizeof(data));
  }

  if (data.mode == 0) {
    // Manual Control
    servo1.write(map(data.joystickX, 0, 1023, 0, 180)); // Control rudder
    analogWrite(16, map(data.joystickY, 0, 1023, 0, 255)); // Control motor
    digitalWrite(BUILTIN_LED, LOW);
  } else if (data.mode == 1) {
    // Heading Hold Mode
    digitalWrite(BUILTIN_LED, LOW);
    int headingError = data.heading - getCurrentHeading(); // Dummy stuff - replace with PID logic
    int correction = map(headingError, 0, 180, 0, 255);
    analogWrite(15, correction); // Adjust motor/servo
  } else if (data.mode == 2) {
    // Blink Mode
    if (millis() - lastBlinkTime >= 1000) {
      ledState = !ledState;
      digitalWrite(BUILTIN_LED, ledState);
      lastBlinkTime = millis();
    }
  }
}

int getCurrentHeading() {
  // Dummy function for now
  return 0;
}
3

Update: So I've managed to get the built in LED on the ESP32 to blink when I press the 3rd button on the Uno. Some success!

4

look over the code below for dealing with buttons,

as for sending data, hoe do you know which byte if the first byte? do you need a preamble to delimit the start of a msg that is synchonized to

// check multiple buttons and toggle LEDs

enum { Off = HIGH, On = LOW };

byte pinsLed [] = { 10, 11, 12 };
byte pinsBut [] = { A1, A2, A3 };
#define N_BUT   sizeof(pinsBut)

byte butState [N_BUT];

// -----------------------------------------------------------------------------
int
chkButtons ()
{
    for (unsigned n = 0; n < sizeof(pinsBut); n++)  {
        byte but = digitalRead (pinsBut [n]);

        if (butState [n] != but)  {
            butState [n] = but;

            delay (10);     // debounce

            if (On == but)
                return n;
        }
    }
    return -1;
}

// -----------------------------------------------------------------------------
void
loop ()
{
    switch (chkButtons ())  {
    case 2:
        digitalWrite (pinsLed [2], ! digitalRead (pinsLed [2]));
        break;

    case 1:
        digitalWrite (pinsLed [1], ! digitalRead (pinsLed [1]));
        break;

    case 0:
        digitalWrite (pinsLed [0], ! digitalRead (pinsLed [0]));
        break;
    }
}

// -----------------------------------------------------------------------------
void
setup ()
{
    Serial.begin (9600);

    for (unsigned n = 0; n < sizeof(pinsBut); n++)  {
        pinMode (pinsBut [n], INPUT_PULLUP);
        butState [n] = digitalRead (pinsBut [n]);
    }

    for (unsigned n = 0; n < sizeof(pinsLed); n++)  {
        digitalWrite (pinsLed [n], Off);
        pinMode      (pinsLed [n], OUTPUT);
    }
}