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Adafruit

· MPN: ADA5954

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The Adafruit TRRS Trinkey is a USB-A plug-in microcontroller designed specifically for assistive technology. It combines an ATSAMD21 processor with a switche...

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The Adafruit TRRS Trinkey is a USB-A plug-in microcontroller designed specifically for assistive technology. It combines an ATSAMD21 processor with a switched TRRS 3.5mm audio jack, connecting all 6 jack pins (tip, ring 1, ring 2, sleeve, plus tip switch and ring 1 switch) to analog-capable GPIO pins. This allows it to detect plug insertion, read switches, potentiometers, or serve as a fully programmable USB HID device.

Simply plug it into any USB-A port and program it with CircuitPython or the Arduino IDE. Over USB, it can act as a serial console, MIDI device, or keyboard/mouse HID — making it easy to map physical switches to custom keyboard commands, mouse actions, or chording patterns. A STEMMA QT / Qwiic port provides optional I2C expansion or two additional inputs.

Key Features

  • ATSAMD21E18 Processor – 48 MHz 32-bit Cortex M0+, 256KB flash, 32KB RAM
  • Switched TRRS Jack – All 6 contacts (tip, ring 1, ring 2, sleeve, tip switch, ring 1 switch) connected to analog-capable GPIO pins
  • Flexible Input Support – Up to 3 simple switches, 2 analog potentiometers, or a combination (with a stereo/mic splitter)
  • Native USB – USB serial, MIDI, keyboard/mouse HID, and USB mass storage
  • CircuitPython & Arduino IDE – UF2 bootloader for easy drag-and-drop programming
  • STEMMA QT / Qwiic Port – JST SH 4-pin connector for I2C devices or two additional inputs
  • Built-in RGB NeoPixel LED – Programmable status indicator
  • Reset Button – Restart code or enter bootloader mode
  • USB-A Plug-In Design – Slides directly into any USB-A port; works with phones/tablets via USB adapter
  • Open Source Hardware – Full control over your assistive technology

Ideal For

  • Assistive technology switches and adaptive input devices
  • Custom USB HID controllers (keyboard, mouse, macro commands)
  • Connecting 3.5mm AT switches to computers and tablets
  • MIDI controllers and musical interfaces
  • Chording input devices

Package Contents

  • 1× Adafruit TRRS Trinkey USB Key

Jargon buster

Plain-language definitions for the technical terms used above.

Bootloader
Small starter software on a microcontroller that lets new code be uploaded before the main program runs. Knowing how to enter bootloader mode matters when you need to program the board or recover it after a faulty sketch.
CircuitPython
A beginner-friendly version of Python designed to run directly on microcontroller boards. If a product supports CircuitPython, you can often program it by copying code files onto the board rather than setting up a more complex toolchain.
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.
HID
Human Interface Device is a USB device class used for keyboards, mice, gamepads and similar controls. If a board supports HID over USB, it can act like an input device to a computer without needing a custom driver.
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.
IDE
Short for Integrated Development Environment, a program used to write, run and manage code. It matters because some learners prefer a traditional coding workspace instead of a guided notebook-style lesson.
LED
A light-emitting diode is a small electronic component that lights up when current flows through it in the correct direction. In this kit, LEDs create the flashing effect, so polarity and correct soldering matter for the project to work.
microcontroller
A microcontroller is a small computer on a chip that runs your program and controls connected inputs and outputs. For this product, it is the part that reads buttons and sensors, drives the display and speaker, and communicates over Bluetooth.
MIDI
MIDI is a standard way for electronic instruments, controllers, and software to send musical control messages such as notes, velocity, and timing. If a board supports MIDI, it can be triggered from keyboards, drum pads, sequencers, or other music gear rather than only from buttons or code.
native USB
Native USB means the microcontroller itself handles USB communication, rather than using a separate USB-to-serial chip. This matters for programming, debugging, and projects that need the board to act directly as a USB device.
NeoPixel
A type of addressable LED system where colour data is sent along a single digital data line from one LED or controller to the next. Compatibility matters because the timing and signal format must match for the lights or driver board to respond correctly.
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.
RAM
RAM is temporary memory used while a device is running, and its contents are lost when power is removed. A “Run in RAM” mode is useful for testing settings without permanently programming the module, but it may not support every feature.
RGB
Short for red, green and blue, usually referring to an LED that can mix those three colours. It matters because controlling an RGB LED teaches how separate outputs combine to create different colours.
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.
USB mass storage
USB mass storage is the standard USB device class used by many flash drives and external storage devices. If a board supports it, your project may be able to read and write files on compatible USB storage, provided the software library also supports the device.

Related Tutorials

Free guides on learn.littlebird.com.au

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