How to Use Adafruit Charlieplex 9x16 Cool White: Examples, Pinouts, and Specs

The Adafruit Charlieplex 9x16 Cool White LED Matrix is a versatile and efficient electronic component designed for displaying patterns, animations, and text. With a total of 144 cool white LEDs arranged in a 9x16 grid, this LED matrix uses the charlieplexing technique to control individual LEDs with fewer I/O pins than would be possible with traditional multiplexing. This makes it an ideal choice for projects with limited GPIO availability, such as wearables, small handheld devices, and compact displays.

• Wearable electronics
• Small-scale information displays
• Decorative lighting
• Visual notifications for devices
• Prototyping for larger LED displays

• Operating Voltage: 3.3V - 5V
• Max Current (per LED): 20mA
• Max Current (total): ~100mA (when all LEDs are on)
• LED Color: Cool White
• Matrix Size: 9x16 (144 LEDs)
• Communication: I2C interface

1. Power Connections: Connect the VCC pin to your power supply (3.3V - 5V) and the GND pin to the ground.
2. I2C Connections: Connect the SDA and SCL pins to the corresponding I2C data and clock lines on your microcontroller (e.g., Arduino UNO).
3. Address Selection: If using multiple matrices, set unique I2C addresses by connecting the ADDR pin to either GND or VCC.

• Ensure that the power supply is within the specified voltage range to prevent damage.
• Limit the number of LEDs lit at the same time to manage power consumption and prevent overheating.
• Use pull-up resistors on the I2C lines if your microcontroller does not have built-in pull-ups.
• When daisy-chaining multiple matrices, verify that the total current does not exceed the power supply capabilities.

#include <Wire.h>
#include <Adafruit_IS31FL3731.h>

// Initialize the Charlieplex matrix
Adafruit_IS31FL3731 matrix = Adafruit_IS31FL3731();

void setup() {
  Wire.begin(); // Start I2C
  matrix.begin(); // Initialize the LED matrix
}

void loop() {
  // Display a pattern on the matrix
  for (int i = 0; i < 144; i++) {
    matrix.drawPixel(i % 16, i / 16, 50); // Set brightness to 50 out of 255
    delay(100);
    matrix.drawPixel(i % 16, i / 16, 0); // Turn off the LED
  }
}

Ensure that the Adafruit_IS31FL3731 library is installed in your Arduino IDE before uploading this code to your Arduino UNO.

• LEDs Not Lighting Up: Check the power supply connections and ensure that the I2C lines are properly connected to the microcontroller.
• Dim or Flickering LEDs: Verify that the power supply can handle the current draw, and check for loose connections.
• I2C Communication Errors: Ensure that there are no address conflicts and that pull-up resistors are in place if needed.

• Double-check wiring against the pin configuration table.
• Use a multimeter to verify that the correct voltage is reaching the matrix.
• If using multiple matrices, ensure each has a unique I2C address.
• Check the Arduino Serial Monitor for error messages that can help diagnose issues.

Q: Can I use this matrix with a 3.3V system? A: Yes, the matrix can operate at 3.3V, but the LEDs may appear dimmer compared to a 5V supply.

Q: How many matrices can I chain together? A: You can chain multiple matrices as long as the total current does not exceed the power supply capacity and each matrix has a unique I2C address.

Q: Do I need external resistors for the LEDs? A: No, the matrix has built-in resistors for current limiting.

For further assistance, consult the Adafruit support forums or the product's official documentation.