🛠 Premier Blink sur la UNO R4 WiFi : la première UNO 32 bits

Objectives

Discover the first 32-bit UNO: the UNO R4 WiFi (Arduino reference ABX00082) is based on the Renesas RA4M1 microcontroller — a Cortex-M4 clocked at 48 MHz with 256 KB of flash and 32 KB of SRAM, compared to 16 MHz, 32 KB of flash, and 2 KB of SRAM for the ATmega328P in the UNO R3. You will upload your first program, make the "L" LED blink, and discover USB-C as well as the new IDE platform.

Hardware

• 1 Arduino UNO R4 WiFi board (the R4 Minima, without the matrix or WiFi, also works for this tutorial)
• 1 USB-C data cable (low-quality charger cables only carry 5 V: no port will appear)
• PC with Arduino IDE 2.x or arduino-cli, with the "Arduino Renesas UNO Boards" platform installed

Complete code

// Blink — LED intégrée « L » sur la pin 13.
const uint8_t LED = 13;

void setup {
  pinMode(LED, OUTPUT);
  Serial.begin(115200);   // le port série passe par le pont embarqué (HIC)
}

void loop {
  digitalWrite(LED, HIGH);
  delay(500);
  digitalWrite(LED, LOW);
  delay(500);
  Serial.println(millis);
}

In the IDE: install the Renesas UNO platform, select Arduino UNO R4 WiFi, choose the displayed port, and Upload. From the command line: arduino-cli compile -b arduino:renesas_uno:unoR4WiFi then arduino-cli upload -b arduino:renesas_uno:unoR4WiFi -p <port>.

Expected verification

The "L" LED blinks every 500 ms and the Serial Monitor scrolls. The program continues to run once the USB is unplugged and the board is powered by the jack (6–24 V accepted): the sketch is burned into flash. Note that, unlike the R3: there is no DTR reset each time the port is opened, so the sketch does not restart when you open the Monitor.

Common errors

• Wrong board type: R4 WiFi and R4 Minima are two distinct targets; the Minima does not have an ESP32-S3 and WiFi examples will fail on it.
• USB-C charging-only cable: no data, no serial port.
• Forgetting the 8 mA per pin limit: never connect an LED without a resistor, and never connect a motor or relay directly.
• Thinking in AVR specifications: the ADC goes up to 14 bits (0–16383) and the SRAM is 32 KB — old habits like F and the 0–1023 range need to be reviewed.
• Upload timing out on a finicky USB hub: flashing goes through the onboard bridge (CMSIS-DAP); connect directly to a PC port.