🛠 Premier sketch : faire clignoter une LED sur Arduino Opta

Objectives

Discover the Arduino Opta, Arduino's certified micro-PLC (STM32H747XI dual-core Cortex-M7 480 MHz + Cortex-M4 240 MHz), by programming your first sketch: making a user LED blink. By the end of this tutorial, you will know how to install the core, upload a sketch, and understand the basic pinout.

Hardware

• An Arduino Opta board (Lite AFX00003, RS485 AFX00001, or WiFi AFX00002)
• A USB-C cable for programming
• A PC with Arduino IDE 2.x
• No 24 V power supply is needed for this test: USB-C powers the processor (but never the relays!)

Complete code

// opta_clignotement_led.ino — core « Arduino Mbed OS Opta Boards »
// Les 4 LED utilisateur sont pilotables via les broches LED1..LED4.

const int LEDS[] = {LED1, LED2, LED3, LED4};

void setup {
  Serial.begin(9600);
  for (int i = 0; i < 4; i++) {
    pinMode(LEDS[i], OUTPUT);
    digitalWrite(LEDS[i], LOW);
  }
  Serial.println("Opta : demo LED prete");
}

void loop {
  for (int i = 0; i < 4; i++) {
    digitalWrite(LEDS[i], HIGH);
    delay(200);
    digitalWrite(LEDS[i], LOW);
  }
}

Expected verification

The 4 user LEDs blink in sequence (a "chaser" effect) every 200 ms. The serial monitor displays the startup message. On the WiFi variant, a fifth network status LED remains managed by the firmware.

Common errors

• Wrong core selected: install "Arduino Mbed OS Opta Boards" (or its successor ArduinoCore-zephyr, same API) in the Boards Manager and choose "Arduino Opta".
• Upload failure: press the RESET button twice quickly (double-click) to enter DFU mode if the sketch hangs, then restart the upload.
• Confusing user LEDs with relay outputs: the relays (D0..D3) control the 230 V load, while LED1..LED4 are simple logical indicators.
• Forgetting the 12–24 VDC power supply in operation: USB-C can never power the relay outputs.