Arduino UNO R4 WiFi, ABX00087 Manual

Description

The Arduino® UNO R4 WiFi is the first UNO board to feature a 32-bit microcontroller and an ESP32-S3 Wi-Fi® module (ESP32-S3-MINI-1-N8). It features a RA4M1 series microcontroller from Renesas (R7FA4M1AB3CFM#AA0), based on a 48 MHz Arm® Cortex®-M4 microprocessor. The UNO R4 WiFi's memory is larger than its predecessors, with 256 kB flash, 32 kB SRAM and 8 kB of EEPROM.
The RA4M1's operating voltage is fixed at 5 V, whereas the ESP32-S3 module is 3.3 V. Communication between these two MCUs is performed via a logic-level translator (TXB0108DQSR).

Target areas:
Maker, beginner, education

• Wi-Fi®
  • Wi-Fi® support with 802.11 b/g/n standard (Wi-Fi® 4)
  • Bit rate at up to 150 Mbps
  • 2.4 GHz band
• Bluetooth®
  • Bluetooth® 5
    See the full datasheet for the ESP32-S3-MINI-1-N8 in the link below:
  • ESP32-S3-MINI-1-N8 datasheet

The Board

Application Examples

The UNO R4 WiFi is part of the first UNO series of 32-bit development boards, being previously based on 8-bit AVR microcontrollers. There are thousands of guides, tutorials and books written about the UNO board, where the UNO R4 WiFi continues its legacy.
The board features 14 digital I/O ports, 6 analog channels, dedicated pins for I2C, SPI and UART connections. It has a significantly larger memory: 8 times more flash memory (256 kB) and 16 times more SRAM (32 kB). With a 48 MHz clock speed, it is also 3x faster than its predecessors.
In addition, it features an ESP32-S3 module for Wi-Fi® & Bluetooth® connectivity, as well as a built-in 12x8 LED matrix, making it one of the most visually unique Arduino boards to date. The LED matrix is fully programmable, where you can load anything from still frames to custom animations.
Entry-level projects: If this is your first project within coding and electronics, the UNO R4 WiFi is a good fit. It is easy to get started with, and it has a lot of online documentation.
Easy IoT applications: build projects without writing any networking code in the Arduino Cloud. Monitor your board, connect it with other boards and services, and develop cool IoT projects.
LED Matrix: the 12x8 LED matrix on the board can be used for showing animations, text scrolling, create minigames and much more, being the perfect feature to give your project more personality.

Related Products

• UNO R3
• UNO R3 SMD
• UNO R4 Minima

Rating

Recommended Operating Conditions

Note: V_DD controls the logic level and is connected to the 5V power rail. V_AREF is for the analog logic.

Functional Overview

Block Diagram

Arduino UNO R4 WiFi Block Diagram

Board Topology

Front View

Top View of Arduino UNO R4 WiFi

Microcontroller (R7FA4M1AB3CFM#AA0)

The UNO R4 WiFi is based on the 32-bit RA4M1 series microcontroller, R7FA4M1AB3CFM#AA0, from Renesas, which uses a 48 MHz Arm® Cortex®-M4 microprocessor with a floating point unit (FPU).
The operating voltage for the RA4M1 is fixed at 5 V as to be hardware compatible with shields, accessories & circuits based on previous Arduino UNO boards.
The R7FA4M1AB3CFM#AA0 features:

• 256 kB flash / 32 kB SRAM / 8 kB data flash (EEPROM)
• Real-time Clock (RTC)
• 4x Direct Memory Access Controller (DMAC)
• 14-bit ADC
• Up to 12-bit DAC
• OPAMP
• CAN bus

For more technical details on this microcontroller, visit the Renesas - RA4M1 series official documentation.

Wi-Fi® / Bluetooth® Module (ESP32-S3-MINI-1-N8)

The Wi-Fi® / Bluetooth® LE module on the UNO R4 WiFi is from the ESP32-S3 SoCs. It features the Xtensa® dualcore 32-bit LX7 MCU, a built-in antenna and support for 2.4 GHz bands.
The ESP32-S3-MINI-1-N8 features:

• Wi-Fi® 4 - 2.4 GHz band
• Bluetooth® 5 LE support
• 3.3 V operating voltage
• 384 kB ROM
• 512 kB SRAM
• Up to 150 Mbps bit rate

This module acts as a secondary MCU on the UNO R4 WiFi, and communicates with the RA4M1 MCU using a logiclevel translator. Note that this module operates on 3.3 V as opposed to the RA4M1's 5 V operating voltage.

ESP Header

ESP header.

The header located close to the RESET button can be used to access the ESP32-S3 module directly. The pins accessible are:

• ESP_IO42 - MTMS debugging (Pin 1)
• ESP_IO41 - MTDI debugging (Pin 2)
• ESP_TXD0 - Serial Transmit (UART) (Pin 3)
• ESP_DOWNLOAD - boot (Pin 4)
• ESP_RXD0 - Serial Receive (UART) (Pin 5)
• GND - ground (Pin 6)

ESP header (schematic)

USB Bridge

When programming the UNO R4 WiFi, the RA4M1 MCU is programmed via the ESP32-S3 module by default. The U2 and U6 switches can switch the USB communication to go directly to the RA4M1 MCU, by writing a high state to the P408 pin (D40).

Soldering together the SJ1 pads permanently sets the USB communication directly to the RA4M1, bypassing the ESP32-S3.

USB Connector

The UNO R4 WiFi has one USB-C® port, used to power and program your board as well as sending & receiving serial communication.
Note: The board should not be powered with more than 5 V via the USB-C® port.

LED Matrix

The UNO R4 WiFi features a 12x8 matrix of red LEDs (U_LEDMATRIX), connected using the technique known as charlieplexing.

The following pins on the RA4M1 MCU are used for the matrix:

• P003
• P004
• P011
• P012
• P013
• P015
• P204
• P205
• P206
• P212
• P213

LED matrix schematics.

These LEDs can be accessed as an array, using a specific library. See the mapping below:
LED matrix number mapping.

This matrix can be used for a number of projects and prototyping purposes, and supports animation, simple game designs and scrolling text among other things.

Digital Analog Converter (DAC)

The UNO R4 WiFi has a DAC with up to 12-bit resolution attached to the A0 analog pin. A DAC is used to convert a digital signal to an analog signal.
The DAC can be used for signal generation for e.g. audio applications, like generating and altering sawtooth waves.

Qwiic I2C Connector

The I2C Qwiic connector SM04B-SRSS-TB(LF)(SN) is connected to a secondary I2C bus on the board. Note that this connector is powered via 3.3 V.
I2C Qwiic connector.

The standard I2C is accessible through the following pin connections:

JANALOG header

• A4
• A5

JDIGITAL header

• SDA
• SCL

Note: as A4/A5 is connected to the main I2C bus, these should not be used as ADC inputs whenever the bus is in use. You can however connect I2C devices to each of these pins and connectors simultaneously.

Power Options

Power can either be supplied via the VIN pin, or via USB-C® connector. If power is supplied via VIN, the ISL854102FRZ buck converter steps the voltage down to 5 V.
Both VUSB and VIN pins are connected to the ISL854102FRZ buck converter, with Schottky diodes in place for reverse polarity & overvoltage protection respectively.
Power via USB supplies about ~4.7 V (due to Schottky drop) to the RA4M1 MCU.
The linear regulator (SGM2205-3.3XKC3G/TR) converts 5 V from either the buck converter or USB, and provides 3.3 V to a number of components, including the ESP32-S3 module.

Power Tree

Arduino UNO R4 WiFi power tree.

Pin Voltage

The general operating voltage for UNO R4 WiFi is 5 V, however the ESP32-S3 module's operating voltage is 3.3 V.
Note: It is very important that ESP32-S3's pins (3.3 V) do not come in contact with any of the RA4M1's pins (5 V), as this may damage the circuits.

Pin Current

The GPIOs on the R7FA4M1AB3CFM#AA0 microcontroller can safely handle up to 8 mA of current. Never connect devices that draw higher current directly to a GPIO as this may damage the circuit.
For powering e.g. servo motors, always use an external power supply.

Mechanical Information

Pinout

Pinout for UNO R4 WiFi.

Analog

Digital

OFF

ICSP

Mounting Holes And Board Outline

Top side Mechanical View of Arduino UNO R4 WiFi

Board Operation

Getting Started - IDE

If you want to program your UNO R4 WiFi while offline you need to install the Arduino® Desktop IDE [1]. To connect the UNO R4 WiFi to your computer, you will need a Type-C® USB cable, which can also provide power to the board, as indicated by the LED (DL1).

Getting Started - Arduino Cloud Editor

All Arduino boards, including this one, work out-of-the-box on the Arduino® Cloud Editor [2], by just installing a simple plugin.
The Arduino Cloud Editor is hosted online, therefore it will always be up-to-date with the latest features and support for all boards. Follow [3] to start coding on the browser and upload your sketches onto your board.

Getting Started - Arduino Cloud

All Arduino IoT enabled products are supported on Arduino Cloud which allows you to log, graph and analyze sensor data, trigger events, and automate your home or business.

Online Resources

Now that you have gone through the basics of what you can do with the board you can explore the endless possibilities it provides by checking existing projects on Arduino Project Hub [4], the Arduino Library Reference [5], and the online store [6]; where you will be able to complement your board with sensors, actuators and more.

Board Recovery

All Arduino boards have a built-in bootloader which allows flashing the board via USB. In case a sketch locks up the processor and the board is not reachable anymore via USB, it is possible to enter bootloader mode by doubletapping the reset button right after the power-up.

Company Information

Reference Documentation