Arduino UNO R4 WiFi Product Reference 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

Features

The R7FA4M1AB3CFM#AA0, often referred to as RA4M1 in this datasheet, is the main MCU on the UNO R4 WiFi, connected to all pin headers on the board as well as all communication buses.

Overview

• 48 MHz Arm® Cortex®-M4 microprocessor with a floating point unit (FPU)
• 5 V operating voltage
• Real-time Clock (RTC)
• Memory Protection Unit (MPU)
• Digital-to-analog Converter (DAC)

Memory

• 256 kB Flash Memory
• 32 kB SRAM
• 8 kB Data Memory (EEPROM)

Peripherals

• Capacitive Touch Sensing Unit (CTSU)
• USB 2.0 Full-Speed Module (USBFS)
• 14-bit ADC
• Up to 12-bit DAC
• Operational Amplifier (OPAMP)

Power

• Operating voltage for RA4M1 is 5 V
• Recommended input voltage (VIN) is 6-24 V
• Barrel jack connected to VIN pin (6-24 V)
• Power via USB-C® at 5V

Communication

• 1x UART (pin D0, D1)
• 1x SPI (pin D10-D13, ICSP header)
• 1x I2C (pin A4, A5, SDA, SCL)
• 1x CAN (pin D4, D5, external transceiver is required)

See the full datasheet for the R7FA4M1AB3CFM#AA0 in the link below: R7FA4M1AB3CFM#AA0 datasheet

The ESP32-S3-MINI-1-N8 is the secondary MCU with a built-in antenna for Wi-Fi® & Bluetooth® connectivity. This module operates on 3.3 V and communicates with the RA4M1 using a logic-level translator (TXB0108DQSR).

Overview

• Xtensa® dual-core 32-bit LX7 microprocessor
• 3.3 V operating voltage
• 40 MHz crystal oscillator

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

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

Recommended Operating Conditions

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

Block Diagram

The block diagram illustrates the architecture of the Arduino UNO R4 WiFi. It shows the main MCU (RA4M1), the Wi-Fi/Bluetooth module (ESP32-S3), USB connectors and switches, power regulation components, and various communication interfaces like UART, I2C, and SPI. The diagram details how these components are interconnected, including the logic-level translator between the two MCUs.

Board Topology

Front View

The front view of the Arduino UNO R4 WiFi board displays the layout of its key components and connectors. This includes the microcontroller (U1), Wi-Fi/Bluetooth module (M1), ESP header (J6), USB-C connector (J1), DC Jack (J5), ICSP header (J3), and I2C connector (J2). Pin headers are arranged along the edges, labeled JDIGITAL, JANALOG, and JOFF. The 12x8 LED matrix is centrally located, and a reset button (PB1) is also visible.

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® LE 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® dual-core 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 logic-level translator. Note that this module operates on 3.3 V as opposed to the RA4M1's 5 V operating voltage.

Antenna

The ESP32-S3-MINI-1-N8 (M1) has a PCB antenna, and has no option to connect an external antenna.

Operations

The ESP32-S3-MINI-1-N8 module provides the UNO R4 WiFi board the possibility to transmit and receive signals using the Wi-Fi® and Bluetooth® Low Energy standards.

Wi-Fi®

• The center frequency range is between 2412 - 2484 MHz.
• The typical Decibel Milliwatts (dBm) using the 802.11b specification for the Wi-Fi RF transmitter is 20.5 dBm at 1 Mbps.
• The typical sensitivity in dBm using the 802.11b specification for the Wi-Fi RF receiver is -98.2 dBm at 1 Mbps.

You can read more about Wi-Fi RF Characteristics at: Page 19 of the ESP32-S3-MINI-1-N8's datasheet.

Bluetooth® Low Energy

The center frequency range for the Bluetooth Low Energy radio is between 2402 - 2480 MHz.

RF transmitter (TX) specifications:

• RF power control range is between -24 dBm to 21 dBm.
• Typical control gain step is 3 Decibels (dB).

You can read more about Bluetooth® RF Characteristics at: Page 21 of the ESP32-S3-MINI-1-N8's datasheet.

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)

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

The LED matrix is composed of 96 individual red LEDs arranged in a 12x8 grid. Each LED is connected via specific pins of the RA4M1 MCU. The diagram shows rows (ROW0 to ROW10) and columns, with resistors (Rxx) of 330 ohms. A mapping table shows how each physical LED position corresponds to a number from 1 to 96, indicating its position within the grid.

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.

I2C Connector

The I2C 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.

The I2C connector (J2) has pins for SCL, SDA, VCC, GND, and FIX. It connects to a +3V3_I2C line and passes through a filter (F1). The connector also shares pin connections with the JANALOG header (A4, A5) and the 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

The power tree diagram illustrates how power is distributed on the Arduino UNO R4 WiFi. Input power comes from the J1 USB-C Connector (VBUS_USB0) or J5 Power Jack (VIN). Both are connected to the U2 Buck Converter (ISL854102FRZ-T), which outputs +5V. This +5V is then supplied to the U1 Microcontroller, M1 Radio Module, and J1 ICSP Connector. A separate +5V rail is also available. The U5 Linear Regulator (SGM2205-3.3XKC3G/TR) takes the +5V and converts it to +3V3, which powers the M1 Radio Module and is available on the J2 I2C Connector and J1 ICSP Connector. Various LEDs (RX, TX, PWR, SCK) are also powered.

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.

Pinout

The pinout diagram shows the physical layout of all connectors and pins on the Arduino UNO R4 WiFi board. It details the ESP32-S3 header with its pins (GP1042, GP1041, GP1043, TXD0, DOWNLOAD, RXD0, GP1044, GND). It also shows the main microcontroller (U1 R7FA4M1AB3CFM) and the Wi-Fi/Bluetooth module (M1 ESP32-S3-MINI-1-N8). Various headers are labeled: USB-C®, Power (VIN, GND, VBATT, VRTC, BOOT, IOREF, RESET), Digital, Analog, I2C (Qwiic), SPI, UART/USART, and PWM/Timer pins. Warnings are present regarding the ESP header's 3.3V signals and the Qwiic connector's 3.3V limitation.

Analog Pins

Digital Pins

OFF

ICSP

Mounting Holes And Board Outline

The mechanical view provides the dimensions and mounting hole locations for the Arduino UNO R4 WiFi board. The overall dimensions are approximately 66.04mm x 53.34mm. Mounting holes are located at specific positions, with corner radii of R1.60mm. Detailed measurements are provided for the board's length, width, and the placement of mounting points.

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 Web Editor

All Arduino boards, including this one, work out-of-the-box on the Arduino® Web Editor [2], by just installing a simple plugin. The Arduino Web 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 IoT Cloud

All Arduino IoT enabled products are supported on Arduino IoT 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 double-tapping the reset button right after the power-up.

Certifications

Declaration of Conformity CE DoC (EU)

Arduino S.r.l. declares under its sole responsibility that the products are in conformity with the essential requirements of the following EU Directives and therefore qualify for free movement within markets comprising the European Union (EU) and European Economic Area (EEA).

Declaration of Conformity to EU RoHS & REACH 211 01/19/2021

Arduino boards are in compliance with RoHS 2 Directive 2011/65/EU of the European Parliament and RoHS 3 Directive 2015/863/EU of the Council of 4 June 2015 on the restriction of the use of certain hazardous substances in electrical and electronic equipment.

Exemptions: No exemptions are claimed.

Arduino Boards are fully compliant with the related requirements of European Union Regulation (EC) 1907 /2006 concerning the Registration, Evaluation, Authorization and Restriction of Chemicals (REACH). We declare none of the SVHCs (https://echa.europa.eu/web/guest/candidate-list-table), the Candidate List of Substances of Very High Concern for authorization currently released by ECHA, is present in all products (and also package) in quantities totaling in a concentration equal or above 0.1%. To the best of our knowledge, we also declare that our products do not contain any of the substances listed on the "Authorization List" (Annex XIV of the REACH regulations) and Substances of Very High Concern (SVHC) in any significant amounts as specified by the Annex XVII of Candidate list published by ECHA (European Chemical Agency) 1907 /2006/EC.

Conflict Minerals Declaration

As a global supplier of electronic and electrical components, Arduino is aware of our obligations with regards to laws and regulations regarding Conflict Minerals, specifically the Dodd-Frank Wall Street Reform and Consumer Protection Act, Section 1502. Arduino does not directly source or process conflict minerals such as Tin, Tantalum, Tungsten, or Gold. Conflict minerals are contained in our products in the form of solder, or as a component in metal alloys. As part of our reasonable due diligence Arduino has contacted component suppliers within our supply chain to verify their continued compliance with the regulations. Based on the information received thus far we declare that our products contain Conflict Minerals sourced from conflict-free areas.

FCC Caution

Any Changes or modifications not expressly approved by the party responsible for compliance could void the user's authority to operate the equipment.

This device complies with part 15 of the FCC Rules. Operation is subject to the following two conditions:

1. This device may not cause harmful interference
2. this device must accept any interference received, including interference that may cause undesired operation.

FCC RF Radiation Exposure Statement:

1. This Transmitter must not be co-located or operating in conjunction with any other antenna or transmitter.
2. This equipment complies with RF radiation exposure limits set forth for an uncontrolled environment.
3. This equipment should be installed and operated with a minimum distance of 20 cm between the radiator & your body.

Note: This equipment has been tested and found to comply with the limits for a Class B digital device, pursuant to part 15 of the FCC Rules. These limits are designed to provide reasonable protection against harmful interference in a residential installation. This equipment generates, uses and can radiate radio frequency energy and, if not installed and used in accordance with the instructions, may cause harmful interference to radio communications. However, there is no guarantee that interference will not occur in a particular installation. If this equipment does cause harmful interference to radio or television reception, which can be determined by turning the equipment off and on, the user is encouraged to try to correct the interference by one or more of the following measures:

• Reorient or relocate the receiving antenna.
• Increase the separation between the equipment and receiver.
• Connect the equipment into an outlet on a circuit different from that to which the receiver is connected.
• Consult the dealer or an experienced radio/TV technician for help.

English: User manuals for licence-exempt radio apparatus shall contain the following or equivalent notice in a conspicuous location in the user manual or alternatively on the device or both. This device complies with Industry Canada licence-exempt RSS standard(s). Operation is subject to the following two conditions:

1. this device may not cause interference
2. this device must accept any interference, including interference that may cause undesired operation of the device.

French: Le présent appareil est conforme aux CNR d'Industrie Canada applicables aux appareils radio exempts de licence. L'exploitation est autorisée aux deux conditions suivantes :

1. l' appareil nedoit pas produire de brouillage
2. l'utilisateur de l'appareil doit accepter tout brouillage radioélectrique subi, même si le brouillage est susceptible d'en compromettre le fonctionnement.

IC SAR Warning:

English This equipment should be installed and operated with a minimum distance of 20 cm between the radiator and your body.

French: Lors de l' installation et de l' exploitation de ce dispositif, la distance entre le radiateur et le corps est d'au moins 20 cm.

Important: The operating temperature of the EUT can't exceed 85 °C and shouldn't be lower than -40 °C.

Hereby, Arduino S.r.l. declares that this product is in compliance with essential requirements and other relevant provisions of Directive 2014/53/EU. This product is allowed to be used in all EU member states.

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