3inch E-Paper Module (G), 400 × 168, Red/Yellow/Black/White

Jargon buster

Plain-language definitions for the technical terms used above.

3.3V and 5V logic levels

Logic level refers to the voltage a digital device uses to represent on and off signals, commonly 3.3V or 5V. When a board supports both 3.3V and 5V logic, it can connect more easily to common microcontrollers and single-board computers without extra level-shifting hardware.

active LOW

Active LOW describes a signal that is treated as active, asserted or 'on' when it sits at a low voltage near ground, rather than at a high voltage. It applies to inputs, outputs and control lines (such as reset or chip-select), so it matters when wiring devices so that signal levels are interpreted as intended.

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.

CS

CS stands for chip select, a control pin used by SPI devices to tell which connected device should listen. It matters when you connect more than one SPI module to the same microcontroller, because each device usually needs its own CS pin.

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.

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.

RST

RST (reset) is a control pin used to restart or reinitialise a device to a known state. Connecting an RST pin to a microcontroller lets the host reset the device, which can help with reliable start-up or recovery.

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.

STM32

STM32 is a family of microcontroller chips commonly used in embedded electronics. Knowing a product uses an STM32 can help when looking at firmware updates, pin connections, or low-level serial control options.

VCC

VCC is the positive power-supply connection on a chip or module. Connecting it to the correct supply voltage is needed for the part to power on and helps avoid damaging the electronics.