Adafruit MPR121 12-Key Capacitive Touch Sensor Gator Breakout - STEMMA QT / Qwiic

Jargon buster

Plain-language definitions for the technical terms used above.

breakout

A breakout board carries a small or fine-pitched component and brings its connections out to standard, breadboard- and header-friendly pins. Describing a part as a breakout means it can be wired into a project without soldering directly to the component's tiny contacts.

capacitive sensing

Capacitive sensing detects changes in electrical capacitance caused by a nearby object or material, such as a finger, water, or moisture in soil. It is used for touch buttons, proximity detection, and liquid or moisture-level sensing, and it matters because it can work without exposed metal contacts, avoiding the corrosion that bare probes suffer in damp conditions.

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.

IRQ

IRQ (interrupt request) is a signal line a device uses to alert a microcontroller that something needs attention, so the microcontroller does not have to poll continuously. Wiring an IRQ pin to a free input lets code respond promptly to events such as new data being ready.

LED

A light-emitting diode (LED) is a small electronic component that emits light when current flows through it in the correct direction. Because it only conducts one way, its polarity matters, and a through-hole LED must be soldered the correct way around to light up.

microcontroller

A microcontroller is a small computer on a single chip that runs a stored program and controls connected inputs and outputs such as buttons, sensors, displays and communication interfaces. In a device built around one, it is the part that executes the code and coordinates the device's behaviour.

Qwiic

Qwiic is a plug-in connector system for I2C devices that uses small 4-pin cables, so you can connect compatible sensors without soldering. It matters because your controller or adapter also needs Qwiic, or you will need a cable or breakout to wire it up.

solder jumper

A solder jumper is a small pair or group of pads on a circuit board that can be bridged or cut with solder to change a hardware setting. It matters because changing modes may require careful soldering rather than just changing software.

STEMMA

A plug-and-cable connection system used on some maker electronics boards to make wiring simpler. If a product uses STEMMA, you need the matching cable or connector type to plug it in without soldering.

STEMMA QT

A small plug-in connector system for I2C boards that lets you connect compatible sensors and controllers without soldering. It matters because it can make wiring faster and less error-prone, especially when adding several small modules to a project.