How to Use Adafruit NeoTrellis 4x4: Examples, Pinouts, and Specs

The Adafruit NeoTrellis 4x4 is a programmable keypad with a built-in RGB LED for each button. This interactive and visually appealing component is perfect for creating custom user interfaces, musical instruments, and gaming controls. Its versatility allows it to be used in a wide range of projects, from simple educational tools to complex interactive installations.

• Musical instruments (e.g., MIDI controllers)
• Gaming controllers
• Custom keyboards
• Interactive LED displays
• Educational projects and learning platforms

• Voltage: 2.5V to 5.5V
• Current: 100 mA for LEDs at full brightness
• Communication: I2C interface
• LEDs: 16 RGB LEDs, one for each button
• Buttons: 16 momentary push buttons
• Dimensions: 60mm x 60mm x 4.6mm

1. Powering the NeoTrellis: Connect the VDD pin to a 2.5V to 5.5V power supply and the GND pin to the ground.
2. I2C Communication: Connect the SCL and SDA pins to the I2C clock and data lines on your microcontroller (e.g., Arduino UNO).
3. Interrupts (Optional): The INT pin can be connected to an interrupt-capable pin on your microcontroller to handle button press events.
4. Reset (Optional): The RST pin can be connected to a digital pin on your microcontroller if you wish to reset the NeoTrellis programmatically.

• Ensure that the power supply voltage is within the specified range to prevent damage.
• Use pull-up resistors on the I2C lines if they are not already present on your microcontroller board.
• To reduce power consumption, manage the brightness of the LEDs appropriately.
• When daisy-chaining multiple NeoTrellis boards, ensure that the I2C addresses are set correctly to avoid conflicts.

#include <Wire.h>
#include "Adafruit_NeoTrellis.h"

Adafruit_NeoTrellis trellis;

void setup() {
  Wire.begin();
  trellis.begin();
  // Activate all keys and LEDs for the NeoTrellis
  for (int i = 0; i < 16; i++) {
    trellis.activateKey(i, SEESAW_KEYPAD_EDGE_RISING, true);
    trellis.setPixelColor(i, 0x000000); // Start with all LEDs off
  }
  trellis.show();
}

void loop() {
  // If available, read key event
  if (trellis.available()) {
    keypadEvent e = trellis.read();
    if (e.bit.EDGE == SEESAW_KEYPAD_EDGE_RISING) {
      trellis.setPixelColor(e.bit.NUM, 0xFFFFFF); // Turn on LED when button is pressed
      trellis.show();
    }
  }
}

• LEDs not lighting up: Ensure that the NeoTrellis is properly powered and that the I2C communication is correctly established.
• Buttons not responding: Check the connections and ensure that the interrupt and reset lines are correctly configured if used.
• Multiple NeoTrellis boards not working together: Verify that each NeoTrellis has a unique I2C address and that the addresses are correctly set in your code.

• Double-check wiring, especially the I2C lines and power connections.
• Use the I2C scanner sketch to confirm that the NeoTrellis is detected on the I2C bus.
• Ensure that the Adafruit NeoTrellis library is correctly installed in your Arduino IDE.
• Check the Adafruit NeoTrellis guide and forums for additional support and resources.

Q: Can I connect multiple NeoTrellis boards together? A: Yes, you can daisy-chain multiple boards using the I2C bus. Make sure to configure unique I2C addresses for each board.

Q: How do I change the color of an LED? A: Use the setPixelColor function with the button number and desired RGB color value.

Q: What is the maximum number of NeoTrellis boards I can chain together? A: The maximum number is limited by the I2C address space and the power supply capability. Typically, you can chain several boards without issues.

Q: Can I use the NeoTrellis with platforms other than Arduino? A: Yes, the NeoTrellis can be used with any microcontroller that supports I2C communication. Adjust the code accordingly for your platform.