Nextion Intelligent NX4827P043-011R touchscreen not establishing communication with the Arduino UNO R4 WiFi board

Projects General Guidance
1

Hello everyone,

I’m currently working on a project involving dimming a 230V AC light using the RobotDyn 4-Channel AC Dimmer (RBD Dimmer), integrated with a Nextion Intelligent Series display (Model: NX4827P043-011R) and an Arduino UNO R4 WiFi board.

At this stage, I’m able to successfully dim the light using the Arduino IDE Serial Monitor. However, I’m facing issues when trying to control the dimming functionality via the Nextion touchscreen interface.

Has anyone implemented a similar setup or encountered similar challenges? Any insights, suggestions, or code examples would be greatly appreciated!

Thank you in advance for your support.

#define ZC_PIN   2
#define CH1_PIN  3
#define CH2_PIN  4
#define CH3_PIN  5
#define CH4_PIN  6

volatile unsigned long zeroCrossTime = 0;
unsigned long fireTimeCH1 = 0, fireTimeCH2 = 0, fireTimeCH3 = 0, fireTimeCH4 = 0;

uint8_t powerCH1 = 50, powerCH2 = 50, powerCH3 = 50, powerCH4 = 50;

String serialInput = "";
String nextionInput = "";

void setup() {
  Serial.begin(9600);     // PC Serial Monitor
  Serial1.begin(9600);    // Nextion Enhanced via Serial1

  pinMode(ZC_PIN, INPUT);
  pinMode(CH1_PIN, OUTPUT);
  pinMode(CH2_PIN, OUTPUT);
  pinMode(CH3_PIN, OUTPUT);
  pinMode(CH4_PIN, OUTPUT);

  attachInterrupt(digitalPinToInterrupt(ZC_PIN), onZeroCross, RISING);

  Serial.println("Enhanced Nextion + AC Dimmer Ready");
}

void loop() {
  // PC Serial Monitor
  while (Serial.available()) {
    char ch = Serial.read();
    if (ch == '\n' || ch == '\r') {
      processCommand(serialInput);
      serialInput = "";
    } else {
      serialInput += ch;
    }
  }

  // Nextion Enhanced
  while (Serial1.available()) {
    char ch = Serial1.read();
    if (ch == '\n' || ch == '\r') {
      processCommand(nextionInput);
      nextionInput = "";
    } else {
      nextionInput += ch;
    }
  }

  unsigned long now = micros();
  if (fireTimeCH1 > 0 && now >= fireTimeCH1) fireTriac(CH1_PIN, &fireTimeCH1);
  if (fireTimeCH2 > 0 && now >= fireTimeCH2) fireTriac(CH2_PIN, &fireTimeCH2);
  if (fireTimeCH3 > 0 && now >= fireTimeCH3) fireTriac(CH3_PIN, &fireTimeCH3);
  if (fireTimeCH4 > 0 && now >= fireTimeCH4) fireTriac(CH4_PIN, &fireTimeCH4);
}

void onZeroCross() {
  zeroCrossTime = micros();
  fireTimeCH1 = zeroCrossTime + (100 - powerCH1) * 80;
  fireTimeCH2 = zeroCrossTime + (100 - powerCH2) * 80;
  fireTimeCH3 = zeroCrossTime + (100 - powerCH3) * 80;
  fireTimeCH4 = zeroCrossTime + (100 - powerCH4) * 80;
}

void fireTriac(uint8_t pin, unsigned long* fireTime) {
  digitalWrite(pin, HIGH);
  delayMicroseconds(10);
  digitalWrite(pin, LOW);
  *fireTime = 0;
}

void processCommand(String input) {
  input.trim();
  input.toLowerCase();

  if (input.startsWith("ch1=")) powerCH1 = constrain(input.substring(4).toInt(), 0, 100);
  else if (input.startsWith("ch2=")) powerCH2 = constrain(input.substring(4).toInt(), 0, 100);
  else if (input.startsWith("ch3=")) powerCH3 = constrain(input.substring(4).toInt(), 0, 100);
  else if (input.startsWith("ch4=")) powerCH4 = constrain(input.substring(4).toInt(), 0, 100);
  else {
    Serial.println("Invalid command. Use ch1=xx, ch2=xx, etc.");
    return;
  }

  Serial.print("Updated → ");
  Serial.print("CH1: "); Serial.print(powerCH1); Serial.print("% | ");
  Serial.print("CH2: "); Serial.print(powerCH2); Serial.print("% | ");
  Serial.print("CH3: "); Serial.print(powerCH3); Serial.print("% | ");
  Serial.print("CH4: "); Serial.print(powerCH4); Serial.println("%");
}
pert 2

I have deleted your other cross-post @hisjuma1.

Cross-posting is against the Arduino forum rules. The reason is that duplicate posts can waste the time of the people trying to help. Someone might spend a lot of time investigating and writing a detailed answer on one topic, without knowing that someone else already did the same in the other topic.

Repeated cross-posting can result in a suspension from the forum.

In the future, please only create one topic for each distinct subject matter. This is basic forum etiquette, as explained in the "How to get the best out of this forum" guide. It contains a lot of other useful information. Please read it.

Thanks in advance for your cooperation.

3

Hello @hisjuma1 ,

I have a tutorial about Nextion HMI here:

If you use the methods set out in the tutorial and get stuck I will try to help you.

I note you have a lot of other code not related to the Nextion. Ideally start simple, make sure you understand how to communicate with the Nextion before adding anything else.