clignotante.ino
The verification blink on the RA4M1: LED_BUILTIN and millis() behave as on AVRs, the USB monitor shows the trace. First test after an upload, before any electronics.
Hardware
An Arduino UNO R4 WiFi (Renesas RA4M1 @ 14 MHz + companion ESP32-S3 Wi-Fi/BLE, 12x8 LED matrix, RGB LED) powered by USB or 6-24 V. No external component.
Wiring
Nothing to wire: the user LED is built in (the 12x8 matrix and the RGB LED are separate outputs).
How it works
The loop compares millis() with the last toggle and flips LED_BUILTIN every second, tracing to serial at 9600 baud.
Running it
Arduino IDE 2.x with the « Arduino UNO R4 Boards » core, « Arduino UNO R4 WiFi » board, serial port then Upload. The ESP32-S3 coprocessor updates separately if the IDE asks.
Variants
On the R4 WiFi, replace with a blink of the internal RGB LED (WS2812 driver) in red/green, or two external LEDs.
clignotante.ino
// Clignotement sur l'UNO R4 : LED_BUILTIN pointe vers la LED
// utilisateur (la LED RGB est pilotee par le WS2812 interne).
const long PERIODE = 1000;
bool etat = false;
unsigned long dernier = 0;
void setup() {
pinMode(LED_BUILTIN, OUTPUT);
Serial.begin(9600);
Serial.println(F("UNO R4 : clignotement demarre"));
}
void loop() {
if (millis() - dernier >= PERIODE) {
dernier = millis();
etat = !etat;
digitalWrite(LED_BUILTIN, etat);
Serial.println(etat ? F("ON") : F("OFF"));
}
}