Raspberry Pi 5 vs. Arduino UNO Q: desktop Linux or Linux with a dedicated controller
The board choice depends on the work attached to the pins, including how it must behave while the operating system is busy.
The unusual part of Arduino UNO Q is the second brain. A Linux processor handles applications while a separate microcontroller runs Arduino sketches over Zephyr. The familiar UNO outline now contains a division of labor.
Arduino’s UNO Q documentation identifies a quad-core Cortex-A53 at 2GHz and an STM32U585 Cortex-M33 running up to 160MHz. The microcontroller has 2MB of flash and 786kB of SRAM. Its job differs from the larger processor’s, so combining their clocks would be a very small math crime.
The Raspberry Pi 5 specification lists a quad-core Cortex-A76 at 2.4GHz, dual 4Kp60 display output, USB ports, Gigabit Ethernet and a standard 40-pin header. It is the more obvious fit when the project starts with a desktop-style Linux computer and peripherals.
| Project requirement | Raspberry Pi 5 | Arduino UNO Q |
|---|---|---|
| Application CPU | Four Cortex-A76 cores, 2.4GHz | Four Cortex-A53 cores, 2GHz |
| Dedicated onboard sketch controller | No separate UNO-style MCU in listed spec | STM32U585, up to 160MHz |
| Display arrangement | Two micro-HDMI outputs | USB-C dongle arrangement documented |
| Device control | Plan the complete hardware/software path | Separate MCU linked through Arduino Bridge |
Arduino calls the MCU’s role “real-time responsiveness.” That describes the intended architecture. It does not establish that every sketch, peripheral or safety requirement is automatically satisfied. A second processor cannot read a project’s mind (one was already struggling).
The Raspberry Pi 5 buyer building a small computer can begin with display, storage, power and cooling needs. Those peripherals form part of the machine’s cost and physical footprint. A bare-board comparison tends to leave the useful computer scattered outside the photograph.
The Arduino UNO Q buyer connecting sensors or actuators should first define what must continue predictably while Linux is busy. That requirement determines whether a separate controller offers a useful boundary. The data exchanged between the two sides then becomes part of the design.
Arduino documents an RPC bridge joining the processors. That is useful, but it also means a project needs to decide what happens if messages arrive late or the Linux application restarts. Merely moving a function to another chip does not define its failure behavior.
The processor clocks differ by 400MHz, but that is a poor shortcut for predicting application speed. The cores are different designs, and the actual workload includes memory, storage and software. A benchmark of the intended application would answer a question the subtraction cannot.
For a simple control project, either Linux board may be more computer than the task needs. Starting with the attached device and its timing requirements leaves room for a smaller controller as a third option. More boards on the shopping list should solve a real problem.
The pins get a vote.