More on: Arduino Uno R4 Minima and WiFi in detail

Features common to Arduino R4 – ‘WiFi’ (€25, below) and ‘Minima’ (€18, right)

IO connections are in physically similar positions to Uno R3, and IO remains 5V. USB connector changed to Type-C.

6 – 24Vin (barrel jack – higher than Uno R3)
5Vin (USB-C)

14x digital GPIOs, D0-D13
(6x PWM: D3,D5,D6,D9,D10,D11)
6x analogue (14bit ADC) input, A0-A5
(A0 pin also true analogue output via 12bit DAC)

Minima on the left and WiFi on the right

Sketch processor is 48MHz (3x Uno R3) Renesas RA4M1 with Arm Cortex-M4 (has floating point maths acceleration)
256kbyte flash (16x UnoR3)
32kbyte ram
8kbyte eeprom

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

USB 2.0 full-speed (able to simulate a mouse or keyboard to a host PC).
Op-amp
Capacitive touch sensing possible

Features only on Uno R4 WiFi (right) and not on Uno Minima

Wi-Fi 2.4GHz 802.11b/g/n up to 150Mbit/s
Bluetooth 5
Built-in antenna
12 x 8 LED matrix
Qwicc-style connector for 3V3 I²C – additional channel from Renesas MCU
Connector to add external battery to real-time clock (RTC) inside Renesas MCU (MCU RTC power pad held to 5V rail on Minima)

Secondary (wireless) processor:
240MHz 3.3V dual core 32bit Espressif ESP32-S3-MINI-1-N8 module (3V3 from local 5V via on-board LDO)
384kbyte rom
512kbyte ram
Dedicated on-board programming header
No access to ‘Arduino’ board-edge IO pins

Two big differences under the hood

One big difference between the two boards is that the Renesas MCU on R4 Minima is programmed directly over USB while, on R4 WiFi the main Renesas MCU is programmed via the ESP32-S3 (Wi-Fi) processor.
To achieve this, the USB bus is connected directly to ESP32-S3 on R4 WiFi – although an on-board jumper allows the USB to be switched over to the Renesas MCU.

A second difference is that Minima has the Renesas MCU debug bought out to connector called ‘SWD’ for connection to an external debugger, while on R4 WiFi the Renesas MCU debug port is taken to the ESP32.
“Uno R4 WiFi includes an error-catching mechanism that detects run-time crashes and provides detailed explanations and hints about the code line causing the crash,” according to Arduino – electronics Weekly has asked for more information on this – so watch this space.

WiFi’s LED matrix

The on-board 12 x 8 (96pixel) matrix of red LEDs (photo right) is Charlieplexed for pixel-level addressing.

Arduino_LED_Matrix API is available for programming and control, and “we have developed a graphic tool designed to help makers create and export their own animations”, according to Arduino.

Circuit diagrams:

WiFi

Minima