The UNO + WiFi R3 is a specialized, integrated development board that combines the familiar architecture of the Arduino UNO (ATmega328P) with the wireless power of the ESP8266. This board eliminates the need for external ESP-01 modules or logic level shifters, providing a compact 32Mb (4MB) flash memory environment for IoT applications. All modules can function together or as independent units via onboard switching.

Specifications

• Microcontroller (MCU): Atmel ATmega328P.
• WiFi MCU: ESP8266 with 32Mb (4MB) Flash.
• USB-to-Serial Converter: CH340G.
• Input Voltage: 6V–9V DC recommended.
• Form Factor: Fully compatible with Uno R3 pinouts and shields.
• Communication: Micro-USB port for programming both chips.

DIP Switch Configuration

The board uses an 8-position DIP switch to route the serial signals between the USB port, the ATmega328P, and the ESP8266.

Features

• Integrated IoT Solution: Combines the robust GPIO handling of the ATmega328P with high-speed WiFi, allowing the Uno to act as a web client or server.
• Standard Uno Pinout: Allows the use of existing Uno shields and peripheral hardware without modification.
• Onboard Voltage Regulation: Converts input voltage safely for both the 5V ATmega and the 3.3V ESP8266 components.
• CH340G Interface: A reliable USB-TTL converter that handles communication and programming for both onboard microcontrollers.

Programming Guide

1. Driver: Ensure the CH340G drivers are installed on your PC.
2. Arduino IDE: Select "Arduino Uno" when programming the ATmega328P and "Generic ESP8266 Module" for the WiFi chip.
3. The Reset Trick: When uploading a sketch to the ATmega328P, press and hold the Reset button while the code is compiling. Release the button immediately when the IDE status changes to "Uploading".
4. ESP8266 Programming: Ensure DIP switches 5, 6, and 7 are ON to put the ESP8266 into flash mode.

Common Applications

• Wireless Data Loggers: Reading analog sensors with the ATmega328P and sending the data to the cloud via the ESP8266.
• Home Automation Gateways: Using the ESP8266 to receive web commands and the Uno to toggle relays or motors.
• WiFi-Enabled Shields: Upgrading existing Uno-based projects with internet connectivity in a single-board footprint.

Usage Tips

• Power Input: While the board can run on USB, using a 9V power adapter is recommended when using WiFi heavily to prevent brownouts.
• Logic Level: The ATmega328P on this board operates at 5V, while the ESP8266 operates at 3.3V. The internal traces are already level-shifted, so they can communicate safely when linked via the DIP switches.
• DIP Switch 8: This switch is generally unused in standard operations and should typically remain OFF.