The latest version of the immensely popular development board Arduino UNO is Rev 4. It is a modernized and refined variant of the classic. Instead of a 16MHz ATMega328P, it now features a 32-bit 48MHz ARM Cortex M4 microcontroller. In addition to a faster and more capable microcontroller, it also offers more memory, a USB-C connector (with HID), improved power supply (6-24V input), CAN-BUS, a 12-bit DAC, and an operational amplifier.

The WIFI model includes everything from the Minima version, and in addition, as the name suggests, a WIFI and Bluetooth module, a 12×8 LED matrix, QWIIC connector, and an RTC (Real-Time Clock) with external battery backup.

UNO Rev 4 is 100% backward compatible with the older UNO boards and has 5V GPIOs. All UNO-compatible shields and codebases also work with the R4 version.

UNO R4 is launched in two versions: a simpler variant (Minima) for all projects based on previous UNO models that require a bit more computational power and memory, and a variant with extended functionality (WIFI) for more advanced projects.

Features
* 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 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)

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®
– 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