Three platforms, three names that constantly appear together in tutorials and forum posts. But they're not variants of the same thing. They're fundamentally different — and the choice between them determines how your project works, how much power it consumes, and what's possible.
Arduino: microcontroller, simple and direct
An Arduino-type board runs one program, continuously, from start to finish. No operating system, no memory management, no processes. You write: when pin 3 goes high, do X. And it does, every time, reliably and fast.
That makes Arduino-type boards the best choice for anything where timing matters: driving a motor, debouncing a button, reading a sensor every 10 ms, positioning a servo precisely. The delay between event and response is predictable — that's called deterministic real-time control.
The limitation is also its strength: there's no easy way to simultaneously maintain a Wi-Fi connection, update a display and read a sensor without careful planning.
Raspberry Pi: small computer, big capability
A Raspberry Pi runs Linux. That means: filesystem, multiple simultaneous processes, Python scripts, networking, SSH, camera, web server. You can run a complete application that also talks to hardware via the GPIO pins.
But Linux is not real-time. There are processes running in the background, memory being swapped, system updates starting. For an LED blinking every second that doesn't matter. For a servo that needs microsecond precision, it does.
The Raspberry Pi shines as the "brain" of a larger system: processing data, making decisions, communicating with the outside world, and delegating hard real-time tasks to an underlying microcontroller.
Choose the device class before the exact board
- Linux-based Raspberry Pi: useful when you need an operating system, network services, files, cameras or multiple processes. Use dedicated hardware or a microcontroller for time-critical I/O when required.
- Microcontroller board: suitable for direct, repeatable control of sensors, switches and actuators. Arduino is an ecosystem of different boards, so check the exact model, MCU, logic levels and interfaces.
- ESP32 board: a microcontroller option with Wi-Fi/Bluetooth on many variants. Design the supply and decoupling for the exact chip and board documentation.
- Raspberry Pi Pico: despite its name, this is a microcontroller board. Pico W variants add wireless connectivity but do not run Raspberry Pi OS.
Do not connect 5 V directly to an input rated only for 3.3 V. Check the absolute maximum and recommended levels for the exact board. For level shifting, use a suitable translator or a calculated circuit that matches direction, speed and load; one resistor value is not a universal solution.
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