Raspberry Pi 4 Model B (2GB RAM)

Jargon buster

Plain-language definitions for the technical terms used above.

BLE

BLE stands for Bluetooth Low Energy, a Bluetooth mode designed for low power use and broad compatibility with modern phones and computers. It connects well to battery-powered and mobile devices, including Apple hardware, though it behaves differently from Bluetooth Classic and its serial-style profiles.

CLK

CLK is a clock line that times when bits are sent and read on a synchronous serial bus such as SPI. Any device using a clock line must have its CLK connected to the controller's clock output so the two stay in step while data is transferred.

DC

DC means direct current, where electricity flows in one constant direction, as supplied by batteries, USB ports and many plug-pack power supplies. When a product specifies DC, it runs from a DC supply rather than mains AC, so you need to provide the correct voltage and polarity.

DIN

As a pin label, DIN stands for 'data in', the input through which a device receives serial data from a controller, as found on SPI displays, LED drivers and other serial modules. DIN can also refer to the German standards body of that name, as in a round multi-pin DIN connector or DIN-rail mounting.

DSI

DSI stands for Display Serial Interface, a high-speed connection commonly used to send video data from a computer board to a display. It matters because DSI signals are not simple GPIO wires, so the cable, connector, and signal routing need to match the display interface.

GND

GND is the ground or reference connection (0 V) for a circuit. When connecting two devices together, their grounds must be joined so both agree on what counts as a low or high signal.

GPIO

General-purpose input/output pins are microcontroller pins you can set in software to read signals, switch devices on and off, or connect to peripherals. The number of GPIO pins matters because it limits how many buttons, LEDs, sensors, and other parts you can wire directly to the board.

H.265

A video compression standard, also called HEVC, that reduces video file size and bandwidth compared with older formats. It matters for vision and AI projects because hardware H.265 encode/decode support can handle many camera streams more efficiently.

HDMI

HDMI is a common digital video and audio connection used by computers, media players, and many displays. If a display kit has HDMI input, it is usually much easier to test with a single-board computer because it can act like a normal monitor.

Headers

Rows of connector contacts on a fixed pitch (commonly 2.54 mm) used to link a board to a breadboard, jumper wires, or another board. They come as male pin headers and female socket headers; when a module ships with pre-soldered headers it can be used straight away, whereas bare pads require soldering the pins yourself.

I2C

I2C is a two-wire communication bus used by many sensors and small modules. It matters because several I2C devices can share the same two wires, but each device needs a compatible address and your controller must support I2C.

LPDDR4

A low-power type of RAM commonly used in phones and embedded computers. More LPDDR4 memory lets a board run larger programs, Linux services, or AI models more smoothly.

microSD card

A microSD card is a small removable flash memory card used to store data such as audio, images, logs or program files. Its capacity and formatting (often FAT32 or exFAT) affect how much can be stored and whether the card needs preparing before use.

PoE

Power over Ethernet lets one Ethernet cable carry both network data and electrical power. This is useful when installing a device where running a separate power adaptor would be difficult.

RAM

RAM (random-access memory) is fast, temporary memory a device uses for working data while it is running; in its common volatile form, its contents are lost when power is removed. Some devices offer a mode that applies settings to RAM only, which is handy for testing changes temporarily because they are not stored permanently and disappear at power-off.

SPI

A fast serial communication bus often used for displays, memory cards, and sensors. It matters because SPI devices need specific pins for clock and data, plus a separate chip-select line for each device.

UART

UART is a simple asynchronous serial interface that sends data over separate transmit and receive wires, usually labelled TX and RX, with both ends set to the same baud rate. It is a common way for microcontrollers and other serial devices to exchange data.

USB 2.0

USB 2.0 is a widely used wired standard for carrying both data and power between a device and a computer or other compatible host, with data rates up to 480 Mbps. It indicates the kind of port a device uses and that it should work with most modern and many older computers.

USB-C

USB-C is a small, reversible USB connector that can carry power, data and, on some devices, video over a single cable. The same connector can range from charging only to high-speed data, so the functions a given port actually supports vary.