The Arduino Uno-compatible board has an MCS-51 (often called 8051 instead) instead of the usual ATmega328P/ATmega168. Specifically, [ElectroBoy] uses the AT89S52.

Arduino has announced the new UNO R4 board family for prototyping and learning. The new models feature a faster microcontroller, a USB-C connector, improved power, Wi-Fi and Bluetooth LE, and more.

This compatibility is achieved with an analog-digital converter and a 3.3 V regulator, mimicking the pins found in an Arduino Uno.

The UNO R4 WiFi features Wi-Fi and Bluetooth Low Energy connectivity, while the UNO R4 Minima provides a cost-effective option for those seeking the new microcontroller without additional features.

Massimo Banzi, co-founder and chairman of Arduino, announced the UNO R4 during Arduino Day 2023. He believes the UNO R4 is a new chapter in the UNO story and the perfect way to move forward, ...

Scheduled to appear in late May, Uno R4 will come in two versions: the plain ‘Uno R4 Minima’, and ‘Uno R4 WiFi’ with an Espressif S3 WiFi module that also gives it Bluetooth Low Energy. “We ...