TinkerNewsWeekly · DIY electronicsEst. 2025
TinkerNews
Board

Arduino Uno R4 Minima specs, pinout & datasheets

Microcontroller board · Arduino · Released June 2023

The 2023 Uno with a 48 MHz Arm Cortex-M4: 16 times the flash and RAM of the R3, USB-C, a DAC and 24 V input, in the same layout.

Arduino Uno R4 Minima
Photo: Arduino, CC BY-SA 3.0, via Wikimedia Commons
CPU
Arm Cortex-M4F
Clock
48 MHz
RAM
32 KB SRAM
Flash
256 KB
I/O voltage
5 V
Released
June 2023
Status
In production

Draft entry: these specs were compiled from the linked sources and are waiting for a second check. Spotted a mistake? Use the form at the end of the page.

Specifications

13 specs
Chip / SoC
Renesas RA4M1 (R7FA4M1AB3CFM)[1]
CPU
Arm Cortex-M4F[1]
Clock
48 MHz[1]
RAM
32 KB SRAM[1]
Flash
256 KB[1]
EEPROM
8 KB data flash[1]
GPIO
14 digital I/O[1]
Analog
6 analog inputs (up to 14-bit); 12-bit DAC on A0[1]
I/O voltage
5 V[1]
Input voltage
6–24 V on VIN or the barrel jack; 5 V via USB-C[1]
USB
USB-C, native USB on the RA4M1 (HID capable)[1]
Launch price
US$20[3]
Upload limits
256 KB flash, 32 KB RAM[4]

Upload limits are what a sketch or firmware may use after the bootloader, as the build tools enforce them, not the chip’s full memory.

Can I still use it?

1 platforms
Arduino framework
Supported[1]Official Arduino core.

As published by each project, checked weekly. A platform not listed has no published information here, which is not the same as no support.

Datasheets and documents

5 documents

Pinout

32 pins
Arduino Uno R3 headers pinout diagramPower1NC2IOREF3RESET43.3V55V6GND7GND8VINAnalog in1A02A13A24A35A46A5Digital 0–71D02D13D24D35D46D57D68D7Digital 8–13, GND, AREF, SDA, SCL1D82D93D104D115D126D137GND8AREF9SDA10SCL
Arduino Uno R3 headers[1]. Same header positions as the Uno R3; pin functions differ (A0 is also a DAC)
  • Power
  • Ground
  • GPIO
  • Special
  • Not connected
Pin table (32 pins)
Power
PinLabelKindFunctions
1NCNot connected
2IOREFPowerI/O reference voltage
3RESETSpecialReset (active low)
43.3VPower
55VPower
6GNDGround
7GNDGround
8VINPowerInput voltage
Analog in
PinLabelKindFunctions
1A0GPIOADC
2A1GPIOADC
3A2GPIOADC
4A3GPIOADC
5A4GPIOADC, I2C SDA
6A5GPIOADC, I2C SCL
Digital 0–7
PinLabelKindFunctions
1D0GPIOUART RX
2D1GPIOUART TX
3D2GPIOINT0
4D3GPIOPWM, INT1
5D4GPIO
6D5GPIOPWM
7D6GPIOPWM
8D7GPIO
Digital 8–13, GND, AREF, SDA, SCL
PinLabelKindFunctions
1D8GPIO
2D9GPIOPWM
3D10GPIOPWM, SPI SS
4D11GPIOPWM, SPI MOSI
5D12GPIOSPI MISO
6D13GPIOSPI SCK, LED
7GNDGround
8AREFSpecialAnalog reference
9SDAGPIOI2C SDA (same as A4)
10SCLGPIOI2C SCL (same as A5)

Gotchas

2 known issues
  • AVR register code does not port. Sketches that write AVR registers directly (PORTB, timers, ISR names) will not compile; libraries that use the Arduino API do.[1]
  • 5 V logic. I/O is 5 V. Sensors and modules that run at 3.3 V (most modern ones) need level shifting on their inputs.[1]

What changed

From the specs

Since the Arduino Uno (R1–R3)

SpecArduino Uno (R1–R3)Arduino Uno R4 Minima
Chip / SoCMicrochip ATmega328PRenesas RA4M1 (R7FA4M1AB3CFM)
CPU8-bit AVRArm Cortex-M4F
Clock16 MHz48 MHz
RAM2 KB SRAM32 KB SRAM
Flash32 KB (0.5 KB used by the bootloader)256 KB
EEPROM1 KB8 KB data flash
GPIO14 digital I/O (6 PWM)14 digital I/O
Analog6 analog inputs (10-bit)6 analog inputs (up to 14-bit); 12-bit DAC on A0
Input voltage7–12 V recommended via barrel jack or VIN; 5 V via USB6–24 V on VIN or the barrel jack; 5 V via USB-C
USBUSB-B via an ATmega16U2 (R3) or ATmega8U2 (R1, R2)USB-C, native USB on the RA4M1 (HID capable)
Dimensions68.6 × 53.4 mm, 25 g—
Launch price—US$20

Next came the Arduino Uno R4 WiFi

SpecArduino Uno R4 MinimaArduino Uno R4 WiFi
Wireless—Wi-Fi and Bluetooth LE via an on-board ESP32-S3
Launch priceUS$20US$27.50

History and use today

Editorial

History

Announced in June 2023, the R4 was the first Uno to move off the AVR, keeping 5 V I/O and the R3 shield layout so existing shields still fit.[1]

Still useful for

The Uno to buy when you want the classic form factor with room for real programs; add the WiFi version if you need wireless or the LED matrix.

Sources

4 sources
  1. Arduino UNO R4 Minima, Arduino documentation
  2. Arduino UNO R4 Minima datasheet (ABX00080)
  3. Arduino Uno, Wikipedia
  4. PlatformIO board definition (uno_r4_minima) at 7a2c1bcc52

Spotted a mistake?

Reviewed by hand

Every report is read by a person and checked against a source before anything changes. Please link one if you have it.

Report a mistake