Also known as: MCU, microcontroller
A microcontroller (MCU) is a tiny, low-power computer on a single chip that combines a processor, memory, and input/output, dedicated to controlling one device or task.1
Overview
Unlike a full computer, a microcontroller has no operating system: your code runs bare metal as the device’s firmware. It boots in milliseconds and can run for years on a small battery, working with only kilobytes of RAM and a modest amount of on-chip flash. That frugality is the point — an MCU does one job reliably and cheaply.
The defining trait is integration: processor, memory, and I/O all live on one chip. Where a desktop CPU needs external RAM, storage, and support chips, a microcontroller packs enough of each to stand alone, exposing its pins as GPIO, an ADC, timers, and serial buses for wiring up the outside world.
How it differs from a single-board computer
A single-board computer like a Raspberry Pi runs a real OS and behaves like a small PC; a microcontroller does not:
| Aspect | Microcontroller | Single-board computer |
|---|---|---|
| Memory | Kilobytes of RAM | Gigabytes |
| Storage | On-chip flash | SD card / eMMC |
| Software | Firmware, bare metal | Full OS (Linux) |
| Boot | Milliseconds | Seconds |
| Power | Milliwatts | Watts |
MCUs are programmed in C, C++, and sometimes Rust or MicroPython, then flashed onto the chip. Popular families include Arduino boards and the Wi-Fi-equipped ESP32.
Where it fits
Microcontrollers are the small radios and controllers that populate the airwaves GopherTrunk listens to, even though they are far too small to run GopherTrunk itself. Around an SDR rig they earn their keep as helpers — reading a sensor, switching an antenna relay, or driving a status display over GPIO — leaving the demodulation and decoding to a general-purpose host.
Sources
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Microcontroller — Wikipedia, on the single-chip design and embedded role of MCUs. ↩