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