Raspberry Pi Glossary & Terminology

A reference list of common terms, protocols, and hardware components encountered in the Raspberry Pi ecosystem.

Core Hardware Terms

SoC (System on a Chip): The main integrated circuit that contains the CPU, GPU, and RAM (e.g., Broadcom BCM2837).
GPIO (General Purpose Input/Output): The physical pins used to interface with external hardware like sensors, LEDs, and buttons.
HAT (Hardware Attached on Top): An add-on board that conforms to the official Raspberry Pi specification, often including an ID EEPROM for automatic configuration.
CSI (Camera Serial Interface): A specialized interface for connecting high-speed camera modules.
DSI (Display Serial Interface): A specialized interface for connecting liquid crystal displays (LCDs).
PoE (Power over Ethernet): A standard that allows the Raspberry Pi (with an appropriate HAT) to be powered via its Ethernet cable.

Raspberry Pi OS: Formerly known as Raspbian; the official Debian-based operating system for the Pi.
NOOBS (New Out Of Box Software): An easy-to-use OS installer and recovery system for beginners.
config.txt: The primary configuration file used to set system and hardware parameters before the Linux kernel boots.
cmdline.txt: Passes command-line arguments to the Linux kernel at boot time.
Device Tree (DT): A database used to describe the hardware configuration to the operating system.

UART (Universal Asynchronous Receiver-Transmitter): Used for serial communication (TX/RX).
I2C (Inter-Integrated Circuit): A multi-device bus using two wires (SDA/SCL) for communication between ICs.
SPI (Serial Peripheral Interface): A high-speed synchronous serial data link.
IR (Infrared): Wireless communication using infrared light.
- Infrared Communication Technology (Wikipedia)

Under-voltage: Occurs when the input voltage drops below ~4.63V, signaled by a lightning bolt icon.
Thermal Throttling: Reducing the CPU clock speed to prevent damage when the SoC temperature exceeds 80°C.