Adafruit
Adafruit Trellis Monochrome Driver PCB for 4x4 Keypad 3mm LEDs
The Adafruit Trellis is an open-source backlight keypad driver system designed to work with the Adafruit 4×4 elastomer keypad and 3mm LEDs. Each tile handles...
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The Adafruit Trellis is an open-source backlight keypad driver system designed to work with the Adafruit 4×4 elastomer keypad and 3mm LEDs. Each tile handles keypress detection and LED control for a 4×4 grid over I2C, and up to 8 tiles can be connected together for a total of 128 buttons and LEDs using just 2 I2C wires.
The onboard I2C chip individually controls all 16 LEDs (on/off, no dimming) and reads keypresses with diode multiplexing to prevent ghosting. Each LED is driven with constant current, so you can mix and match any colours of 3mm LEDs. An Arduino or other microcontroller is required to control the Trellis — the PCB does not include any onboard processing.
Key Features
- 4×4 Keypad and LED Driver – Controls 16 LEDs and reads 16 button presses per tile
- I2C Interface – Simple 2-wire connection with 3 address jumpers for up to 8 unique addresses
- Tileable Design – Connect up to 8 tiles edge-to-edge (up to 128 buttons/LEDs) sharing power, ground, interrupt, and I2C lines
- Anti-Ghosting – Diode-multiplexed key connections for accurate multi-key detection
- Constant-Current LED Driver – Mix and match any colours of 3mm LEDs
- Flexible Layout – Tiles can be arranged in any configuration as long as each is connected via the 5 edge-fingers
- A Silicone Elastomer 4×4 Button Keypad for 3mm LEDs
- 3mm diffused LEDs (red, blue, or white look best at 250+ mcd brightness)
- An Arduino or compatible microcontroller
Ideal For
- Custom MIDI controllers and music interfaces
- LED button grids and step sequencers
- Interactive control panels
- DIY macro keypads
Package Contents
- 1× Adafruit Trellis Monochrome Driver PCB (assembled, no LEDs or buttons)
Resources
Jargon buster
Plain-language definitions for the technical terms used above.
- Address jumpers
- Address jumpers are small solder pads, links or switches used to change a device's address on a shared bus such as I2C. They matter when you want to connect several identical devices to the same controller, since each one needs a unique address to avoid conflicts.
- 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.
- 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.
- LED driver
- An LED driver is a control chip or circuit that supplies and switches power to LEDs. For a display board, it reduces the number of microcontroller pins needed and handles tasks like lighting the right segments and adjusting brightness.
- 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.
- 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.
- PCB
- A printed circuit board (PCB) is a board, usually rigid, with etched copper tracks that connect electronic components together without loose wiring. Components are mounted on the board and signals route between them through the copper layout.
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Prototyping & Wiring
adafruit trellis diy open source led keypad
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