Arduino Uno R4 Wifi

1. Description
The Arduino UNO R4 WiFi (hereafter for 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 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 12×8 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.

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).

2. Features
R7FA4M1AB3CFM#AA0, also called RA4M1, is the main MCU on UNO R4 WiFi board, which connects to all pins on the board and 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 Analog Converter (DAC)

Memory

256 kB Flash Memory

32kB 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

RA4M1 operating voltage is 5V

Recommended input voltage (VIN) is 6-24 V

Barrel jack connected to VIN pin (6-24V)

Power via USB-C® at 5 V

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)

Operating temperature: -40℃~85℃

esp32 – s3 mini -1- n8 is a secondary MCU with a built-in antenna for Wi-Fi® and Bluetooth® connection. This module works at 3.3V, and communicates with RA4M1 through a logical level translator (TXB0108DQSR).

Overview

Xtensa® Dual-core 32-bit LX7 microprocessor

Operating voltage of 3.3V

40 MHz crystal oscillator

Wi-Fi®

Wi-Fi® supports 802.11 b/g/n standard (Wi-Fi®4)

Bit rate up to 150 Mbps

Frequency band of 2.4 GHz

Bluetooth®

Bluetooth® 5

3. Functions
3.1. Board Topology
Img

Ref.

Description

U1

R7FA4M1AB3CFM#AA0 Microcontroller IC

U2

NLASB3157DFT2G multiplexer

U3

ISL854102FRZ-T Buck converter

U4

TXB0108DQSR Logic level converter（5 V – 3.3 V）

U5

SGM2205-3.3XKC3G/TR 3.3 V Linear voltage regulator

U6

NLASB3157DFT2G multiplexer

U_LEDMATRIX

12×8 LED red matrix

M1

ESP32-S3-MINI-1-N8

PB1

RESET button

JANALOG

Analog input/output headers

JDIGITAL

Digital input/output headers

JOFF

OFF, VRTC headers

J1

CX90B-16P USB-C® connector

J2

SM04B-SRSS-TB(LF)(SN) I2C connector

J3

ICSP headers (SPI)

J5

DC power jack

J6

ESP headers

DL1

LED TX (serial transmit)

DL2

LED RX (serial receive)

DL3

LED Power (green)

DL4

LED SCK (serial clock)

D1

PMEG6020AELRX Schottky Diode

D2

PMEG6020AELRX Schottky Diode

D3

PRTR5V0U2X, 215 ESD Protection

3.2. 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).

On the board, the operating voltage is fixed at 5 V to be fully retro compatible with shields, accessories & circuits originally designed for older UNO revisions.

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)

up to 14-bit ADC

up to 12-bit DAC

OPAMP

1x CAN bus

3.3. 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® 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.

3.4. ESP Header
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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)

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3.5. 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).

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

3.6. 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.

3.7. LED Matrix
The UNO R4 WiFi features a 12×8 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

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

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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.

3.8. 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.

3.9. 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.

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This connector also shares the following pin connections:

JANALOG headers

A4

A5

JDIGITAL headers

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.

3.10. 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 3.3V to a number of components, including the ESP32-S3 module.

Power Tree

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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.

4. Pin-out
Img

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4.1. Analog
Pin

Function

Type

Description

1

BOOT

NC

Not Connected

2

IOREF

IOREF

Reference for digital logic V – connected to 5 V

3

Reset

Reset

Reset

4

+3V3

Power

+3V3 Power Rail

5

+5V

Power

+5V Power Rail

6

GND

Power

Ground

7

GND

Power

Ground

8

VIN

Power

Voltage Input

9

A0

Analog

Analog input 0 / DAC

10

A1

Analog

Analog input 1 / OPAMP+

11

A2

Analog

Analog input 2 / OPAMP-

12

A3

Analog

Analog input 3 / OPAMPOut

13

A4

Analog

Analog input 4 / I2C Serial Datal (SDA)

14

A5

Analog

Analog input 5 / I2C Serial Clock (SCL)

4.2. Digital
Pin

Function

Type

Description

1

SCL

Digital

I2C Serial Clock (SCL)

2

SDA

Digital

I2C Serial Datal (SDA)

3

AREF

Digital

Analog Reference Voltage

4

GND

Power

ground

5

D13/SCK/CANRX0

Digital

GPIO 13 / SPI Clock / CAN Receiver (RX)

6

D12/CIPO

Digital

GPIO 12 / SPI Controller In Peripheral Out

7

D11/COPI

Digital

GPIO 11 (PWM) / SPI Controller Out Peripheral In

8

D10/CS/CANTX0

Digital

GPIO 10 (PWM) / SPI Chip Select / CAN Transmitter (TX)

9

D9

Digital

GPIO 9 (PWM~)

10

D8

Digital

GPIO 8

11

D7

Digital

GPIO 7

12

D6

Digital

GPIO 6 (PWM~)

13

D5

Digital

GPIO 5 (PWM~)

14

D4

Digital

GPIO 4

15

D3

Digital

GPIO 3 (PWM~) / Interrupt Pin

16

D2

Digital

GPIO 2 / Interrupt Pin

17

D1/TX0

Digital

GPIO 1 / Serial 0 Transmitter (TX)

18

D0/TX0

Digital

GPIO 0 / Serial 0 Receiver (RX)

4.3. OFF
Pin

Function

Type

Description

1

OFF

Power

For controlling power supply

2

GND

Power

Ground

1

VRTC

Power

Battery connection to power RTC only

4.4. ICSP
Pin

Function

Type

Description

1

CIPO

Internal

Controller In Peripheral Out

2

+5V

Internal

5V Power

3

SCK

Internal

Serial Clock

4

COPI

Internal

Controller Out Peripheral In

5

RESET

Internal

Reset

6

GND

Internal

Ground

For more information of UNO R4 WiFi board, please visit: https://docs.arduino.cc/hardware/uno-r4-wifi/

Ⅱ. UNO R4 Minima Board
Img

1. Description
The Arduino® UNO R4 Minima is the first UNO board to feature a 32-bit microcontroller. It features a RA4M1 series microcontroller from Renesas (R7FA4M1AB3CFM#AA0), which embeds a 48 MHz Arm® Cortex®-M4 microprocessor.

The board features the standard 14 digital I/O ports, 6 analog channels, dedicated pins for I2C, SPI and UART connections. Compared to its predecessors the board has a much larger memory: 8 times more flash memory (256 kB) and 16 times more SRAM (32 kB) as well as 8 kB data memory (EEPROM).

has a barrel jack connector and supports input voltages from 6-24 V. This connector is widely popular and removes the need for additional circuitry required to step down the voltage.

The UNO R4 Minima board’s operating voltage is 5 V, making it hardware compatible with UNO form factor accessories with the same operating voltage. Shields designed for previous UNO revisions are therefore safe to use with this board but are not guaranteed to be software compatible due to the change of microcontroller.

2. Features
R7FA4M1AB3CFM#AA0

48 MHz Arm® Cortex®-M4 microprocessor with a floating point unit (FPU).

5V operating voltage

Real-time Clock (RTC)

Memory Protection Unit (MPU)

Digital-to-analog Converter (DAC)

Memory

256kB flash memory

32kB SRAM

8 kB Data Memory (EEPROM)

Header

14 digital I/O pins (GPIO), D0-D13

6 analog input pins (ADC), A0-A5

6 PWM pins: D3, D5, D6, D9, D10, D11

Peripherals

Capacitive Touch Sensing Unit (CTSU)

USB 2.0 Full-Speed Module (USBFS)

Up to 14-bit ADC

Up to 12-bit DAC

Operational Amplifier (OPAMP)

Power

Operating voltage is 5V

Recommended input voltage (VIN) is 6-24 V

Barrel jack connected to VIN pin (6-24 V)

Power via USB-C® at 5 V

Schottky diodes are used for over-voltage and reverse polarity protection

Communication

1x UART (D0, D1)

1x SPI (D10-D13, ICSP header)

1x I2C (A4, A5, SDA, SCL)

1x CAN (D4, D5, external transceiver is required)

Operating temperature: -40℃~85℃

3. Functions
3.1. Board Topology
Img

Ref.

Description

U1

R7FA4M1AB3CFM#AA0 Microcontroller IC

U2

ISL854102FRZ-T Buck Converter

PB1

RESET Button

JANALOG

Analog input/output headers

JDIGITAL

Digital input/output headers

J1

ICSP header (SPI)

J2

SWD/JTAG Connector

J3

CX90B-16P USB-C® Connector

J4

DC Jack

DL1

LED TX (serial transmit)

DL2

LED RX (serial receive)

DL3

LED Power (green)

DL4

LED SCK (serial clock)

D2

PMEG6020AELRX Schottky Diode

D3

PMEG6020AELRX Schottky Diode

D4

PRTR5V0U2X, 215 ESD Protection

3.2. Microcontroller (R7FA4M1AB3CFM#AA0)
The UNO R4 Minima 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).

On the UNO R4 Minima, the operating voltage is fixed at 5 V to be fully retro compatible with shields, accessories & circuits originally designed for older UNO revisions.

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)

up to 14-bit ADC

up to 12-bit DAC

OPAMP

CAN bus

3.3. USB Connector
The UNO R4 Minima has one USB-C® port, used to power and program your board as well as send & receive serial communication.

NOTE: You should not power the board with more than 5 V via the USB-C® port.

3.4. Digital Analog Converter (DAC)
The UNO R4 Minima 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.

3.5. Power Options
Power can either be supplied via the VIN pin, the barrel jack, or via USB-C® connector. If power is supplied via VIN, the ISL854102FRZ buck converter steps the voltage down to 5 V.

The VUSB, barrel jack connector 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 microcontroller.