UNO+WiFi R3 ATmega328P+ESP8266, 32Mb flash, USB-TTL CH340G, Micro-USB

Discontinued RobotDyn SKU: RD-UNO-WIFI-R3
UNO+WiFi R3 ATmega328P+ESP8266, 32Mb flash, USB-TTL CH340G, Micro-USB

Overview

The RobotDyn UNO+WiFi R3 combines an Arduino UNO R3 (ATmega328P) with an ESP8266EX Wi-Fi module on a single shield-compatible board. Both MCUs share a CH340G USB-TTL converter for programming over a single Micro-USB cable.

Unlike Wi-Fi shields, the ESP8266 here is a full microcontroller with its own 32 Mb (4 MB) of flash — enough to run web servers, MQTT clients, or OTA-updatable firmware independently of the ATmega.

Why Use This Board

For IoT projects where you want UNO-level simplicity but need Wi-Fi without sacrificing shield compatibility. The board fits standard Arduino UNO shields (with awareness — see warnings below) while adding wireless connectivity.

Compared to standalone ESP8266 boards (like NodeMCU): you get 5 V I/O on the ATmega side (compatible with most existing Arduino sensors and shields), plus more reliable real-time control.

DIP Switch Configuration

The 8-position DIP switch (from the original RobotDyn documentation):

Mode12345678
CH340 → ESP8266 (upload firmware)OFFOFFOFFOFFONONON—
CH340 → ESP8266 (connect/serial monitor)OFFOFFOFFOFFONONOFF—
CH340 → ATmega328 (upload sketch)OFFOFFONONOFFOFFOFF—
ATmega328 ↔ ESP8266 (independent USB)ONONOFFOFFOFFOFFOFF—
All independent (no connections)OFFOFFOFFOFFOFFOFFOFF—

DIP 8 is reserved (unused).

Programming

ESP8266 Setup in Arduino IDE

To program the ESP8266 side, install the ESP8266 board package:

  1. File → Preferences → Additional Boards Manager URLs, add: 
    http://arduino.esp8266.com/stable/package_esp8266com_index.json
  2. Tools → Board → Boards Manager, search esp8266 by ESP8266 Community, install (version 2.1.0+)
  3. Tools → Board → Generic ESP8266 Module
  4. Tools → Upload Speed → 115200

Upload to ATmega328P (Uno)

  1. Set DIP 3, 4 = ON; rest OFF
  2. Tools → Board → Arduino Uno
  3. Upload as normal

Upload Firmware to ESP8266

  1. Set DIP 5, 6, 7 = ON to enter flash mode
  2. Press the ESP Reboot button before upload
  3. Upload from Arduino IDE
  4. Return DIP 7 = OFF to run normally

MCU-to-MCU Serial

Set DIP 1, 2 = ON. ATmega’s hardware Serial (pins 0/1) connects to ESP8266’s UART. The board includes voltage level shifters on this line.

Note: Because the ESP8266 shares pins 0/1 (RX/TX) with the ATmega’s USB serial, you cannot easily debug via Serial.print() while ESP communication is active. Use SoftwareSerial on other pins for debugging, or disable DIP 1, 2 temporarily.

Example: ATmega controls ESP8266 LED via Serial

This sketch (from the original RobotDyn documentation) configures the ESP8266 as a TCP server on port 5000 and toggles an LED on pin 14 (A0) based on received characters:

void setup() {
  Serial.begin(115200);
  pinMode(14, OUTPUT);
  delay(500);
  Serial.println("AT+CIPMUX=1");
  delay(2000);
  Serial.println("AT+CIPSERVER=1,5000");
  delay(2000);
  Serial.println("AT+CIPSTO=3600");
  delay(2000);
}

void loop() {
  while (Serial.available()) {
    char Rdata;
    Rdata = Serial.read();
    if (Rdata == 'A' || Rdata == 'a') {
      digitalWrite(14, HIGH);
      delay(50);
    } else if (Rdata == 'B' || Rdata == 'b') {
      digitalWrite(14, LOW);
      delay(10);
      digitalWrite(14, HIGH);
      delay(10);
      digitalWrite(14, LOW);
    } else {
      digitalWrite(14, LOW);
    }
  }
}

Set DIP 1, 2 = ON to bridge ATmega↔ESP, upload, then telnet to the board’s IP on port 5000.

Logic Level Warning

The ATmega328P side runs at 5 V, but the ESP8266 is 3.3 V tolerant only. The board includes voltage level shifters on the inter-MCU communication lines, but if you’re wiring external sensors to ESP8266 GPIOs, do not exceed 3.3 V on those pins.

Common Uses

Where to Buy in 2026

Compatible clones are widely available on AliExpress and Amazon. Look for boards with CH340G (not CH340T or older variants) and 32 Mb flash to match this exact configuration.

Documentation