Feature: Embedded design
a pivotal shift from the legacy 8-bit AVR architecture used in earlier Arduino UNO models, offering a substantial increase in processing power, memory and peripheral capabilities. With 256KB of flash memory and 32KB of SRAM, the RA4M1 enables more sophisticated applications such as real-time signal processing, sensor fusion and advanced control algorithms. Despite this performance leap, the familiar UNO form factor and pinout remain unchanged, thus ensuring backward compatibility with the UNO R3 series. Table 1 shows a detailed comparison between the UNO R3 and the UNO R4:
With increasing demands for real-time responsiveness, wireless integration and complex multi-tasking capabilities, the limitations of the R3 became increasingly apparent
Key advantages of the UNO R4 Te Renesas RA4M1 microcontroller in the UNO R4 offers significant advantages: • Performance: Tree times the clock speed of the UNO R3. • Memory: 32KB SRAM and 256KB flash enable more complex applications.
• Connectivity: Wi-Fi and Bluetooth (WiFi version), CAN bus, Qwiic I2
C.
• Peripheral Expansion: 12-bit DAC, 14-bit ADC, HID support, op-amp.
• Power: USB-C interface and increased input voltage range (up to 24V). Notice that almost all the projects and libraries used with
the UNO R3 can be used with the UNO R4 without any modifications. It is recommended however to upgrade any libraries which may have been modified specifically for the UNO R4. UNO R4 includes a true 12-bit DAC converter. Te
AnalogWave library allows developers to easily generate analogue waveforms like sine, square or sawtooth, thus enhancing real- time signal generation capabilities. Compared to other Cortex-based boards such as the Raspberry
Pi Pico, which uses the Cortex M0+, the Cortex-M4 performance is about six times better. Just to remind you, the Raspberry Pi Pico clock runs at 125MHz by default. As a result, the Arduino UNO R4 can be used in highly complex real-time projects (e.g., digital control, DSP, AI, etc.) requiring large memory and fast throughput. Arduino UNO R4 comes in two configurations:
1. UNO R4 Minima: A cost-effective variant without wireless capabilities, ideal for education, standalone systems and analogue-centric applications. Despite the minimal design, the R4 Minima includes powerful features such as the 12-bit DAC, CAN bus, SWD debug interface and 14-bit ADC. 2. UNO R4 WiFi: Features an Espressif S3 module for Wi-Fi and Bluetooth LE connectivity, plus a built-in 128 × 8 LED matrix and RTC, making it suitable for IoT and remote interface applications.
Table 1: Comparison of the Arduino UNO R3 and UNO R4
The Arduino UNO R4 Minima hardware Arduino R4 Minima is designed as a lean, cost-effective option for users who prioritise processing power and analogue capabilities over wireless communication. It is ideal for
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