Arduino UNO R4 Minima Pinout: GPIO, DAC, CAN, RTC and USB

The Arduino UNO R4 Minima is the simplest way to get the Renesas RA4M1 architecture in the traditional UNO form factor.

It has no ESP32-S3, no Wi-Fi, no Bluetooth, no LED matrix and no Qwiic connector. Instead, it focuses on the 48 MHz RA4M1, 5 V logic, native USB, higher-resolution ADC, true DAC, CAN controller, RTC and integrated op-amp.

UNO R4 Minima Specifications

Feature	UNO R4 Minima
MCU	Renesas RA4M1, Arm Cortex-M4
Clock	48 MHz
Logic voltage	5 V
Flash	256 kB
SRAM	32 kB
Data memory	8 kB
Digital I/O	14
Analog inputs	6
ADC	Up to 14 bit
DAC	12-bit on A0
CAN	Classic CAN controller
RTC	Built in
USB	Native USB-C

Digital Pinout

Pin	Main functions
D0	RX, GPIO
D1	TX, GPIO
D2	GPIO, interrupt
D3	GPIO, PWM, interrupt
D4	GPIO, CAN TX
D5	GPIO, PWM, CAN RX
D6	GPIO, PWM
D7	GPIO
D8	GPIO
D9	GPIO, PWM
D10	GPIO, PWM, SPI CS
D11	GPIO, PWM, SPI COPI/MOSI
D12	GPIO, SPI CIPO/MISO
D13	GPIO, SPI SCK, LED_BUILTIN

PWM

The official PWM header pins are:

analogWrite() defaults to an 8-bit value range, while the RA4M1 timers support higher resolution through analogWriteResolution().

Analog Inputs

Pin	Functions
A0	ADC, DAC
A1	ADC, OPAMP+
A2	ADC, OPAMP-
A3	ADC, OPAMP output
A4	ADC, SDA
A5	ADC, SCL

14-Bit ADC

The R4 Minima defaults to 10-bit reads for compatibility, but you can request 12- or 14-bit results:

At 14 bits, the numerical range is 0–16383. Resolution is not the same thing as absolute measurement accuracy, so reference voltage, source impedance and noise still matter.

12-Bit DAC on A0

A0 can output a true analog voltage from the RA4M1 DAC.

This is a true DAC output rather than PWM.

Integrated Op-Amp

This peripheral can be used for analog signal conditioning, active filtering and buffering.

I²C

Use Wire.

SPI

The traditional SPI header is also provided for shield compatibility.

UART

Use Serial1 for the external UART. The native USB connection uses Serial, so USB serial and the physical UART are independent.

CAN Bus

UNO R4 Minima has a real CAN controller inside the RA4M1.

An external CAN transceiver is still required. The MCU pins are logic-level controller signals, not CANH/CANL.

RTC

The RA4M1 contains a real-time clock capable of maintaining calendar time and generating alarms. Arduino provides an RTC library for R4 boards.

The RTC is useful for data loggers, scheduled control, timestamps and low-power wake-up applications.

Native USB-C

UNO R4 Minima uses native USB from the RA4M1. This enables:

• programming;
• USB serial;
• keyboard/mouse HID;
• custom USB applications supported by the core.

5 V Logic

The board’s standard digital I/O operates at 5 V. This makes it much easier to use with older UNO shields and legacy 5 V modules than most modern 32-bit boards.

However, 5 V compatibility does not mean every old library is compatible. Direct AVR register code for:

will not work on the RA4M1.

Memory Upgrade over UNO R3

Memory	UNO R3	UNO R4 Minima
Flash	32 kB	256 kB
SRAM	2 kB	32 kB
Non-volatile data	1 kB EEPROM	8 kB data memory

Power

Arduino documents the VIN input range as approximately 6–24 V. USB-C must be powered at 5 V.

When using higher VIN voltages, remember that onboard power conversion still has thermal/current limits. Motors and large servos should use their own suitable supply.

R4 Minima vs R4 WiFi

The Minima and WiFi boards share the RA4M1 application architecture and most header functions.

UNO R4 WiFi adds:

• ESP32-S3 wireless connectivity;
• 12×8 LED matrix;
• 3.3 V Qwiic connector;
• more complicated USB/bridge architecture.

Minima is simpler when you do not need wireless connectivity.

Quick Reference

Final Thoughts

The UNO R4 Minima is a straightforward 32-bit upgrade path for classic UNO projects when you want to retain 5 V logic and shield compatibility.

Its most useful hardware upgrades are not just CPU speed. The 14-bit ADC, true DAC, CAN controller, RTC, native USB and integrated op-amp make it a substantially more capable embedded controller than the UNO R3 while keeping the familiar UNO physical format.