A complete computer built on a single circuit board. Includes processor, memory, storage, and I/O interfaces. Runs a full operating system (typically Linux). Used for complex IoT applications requiring high processing power.
Headed vs Headless
- Headed
Board operates with a display, keyboard, and mouse attached. Provides a full graphical user interface. Used during development or in applications that require a local UI. - Headless
Board operates without a display or input peripherals. Accessed remotely via SSH or serial console. Preferred in deployed IoT systems where a local UI is unnecessary.
Examples
Raspberry Pi
SBC developed by the Raspberry Pi Foundation. ARM-based processor. Runs Raspberry Pi OS (Debian-based Linux) or other Linux distributions.
Used for IoT applications requiring significant processing power, networking, or a full OS environment.
Capabilities:
- Camera and display support via dedicated connectors
- High-speed networking via Ethernet and Wi-Fi
- GPIO header for sensor and actuator integration
- Runs any software available for Linux (Python, Node.js, databases, ML frameworks)
Hardware
The main board (Pi 4 as reference):
- SoC
Broadcom BCM2711, quad-core ARM Cortex-A72 @ 1.8 GHz. - RAM
1–8 GB LPDDR4. - Storage
microSD card (no onboard flash). - Connectivity
Gigabit Ethernet, dual-band Wi-Fi, Bluetooth 5.0. - USB
2× USB 3.0, 2× USB 2.0. - Video
2× micro-HDMI (up to 4K). - GPIO
40-pin header.
GPIO
40-pin header exposing digital I/O and peripheral bus signals.
Pin types:
- Digital I/O (3.3 V logic, not 5 V tolerant)
- SPI, I²C, UART buses
- PWM outputs
- 3.3 V and 5 V power pins
Programming
Any language that runs on Linux is usable. Common choices:
- Python (most common;
RPi.GPIOorgpiozerolibraries for GPIO) - C/C++ (via
wiringPior direct/dev/memaccess) - Node.js, Java, Go
GPIO response time is slower than a bare-metal MCU due to OS scheduling overhead. Not suitable for hard real-time tasks.
Raspberry Pi Pico
Microcontroller board (not an SBC) from the Raspberry Pi Foundation. Does not run Linux.
Based on the RP2040 chip:
- Dual-core ARM Cortex-M0+ @ 133 MHz
- 264 KB SRAM
- 2 MB onboard flash
- 26 GPIO pins
- 3 ADC channels
- USB, SPI, I²C, UART, PWM, PIO
Primary languages: MicroPython and C/C++. Behaves like an Arduino-class device rather than a full SBC.