How to Use Adafruit Blue 15x7 CharliePlex FeatherWing: Examples, Pinouts, and Specs

The Adafruit Blue 15x7 CharliePlex FeatherWing is an LED matrix display panel that provides a simple way to add a vibrant visual display to your projects. It features a grid of 105 blue LEDs arranged in a 15x7 pattern. This component is designed to be used with the Feather series of development boards from Adafruit, which are compact, easy to use, and versatile for a wide range of applications.

• Displaying text messages
• Creating animations and patterns
• Building wearable electronics with visual feedback
• Adding visual indicators for IoT devices
• Prototyping user interfaces for embedded systems

• LED Color: Blue
• Matrix Size: 15x7 (105 LEDs)
• Operating Voltage: 3.3V to 5V DC
• Communication Interface: I2C
• I2C Addresses: 0x70 (default), selectable with solder jumpers
• Dimensions: 51mm x 23mm x 2.5mm

1. Power Connections: Connect the VIN pin to the 3.3V or 5V output on your Feather board and GND to ground.
2. I2C Connections: Connect the SDA and SCL pins to the corresponding I2C pins on your Feather board.
3. Address Selection: If using multiple CharliePlex FeatherWings, change the I2C address using the ADDR solder jumpers.
4. Mounting: The CharliePlex FeatherWing can be directly attached to the headers on a Feather board.

• Ensure that the power supply voltage matches the requirements of the Feather board.
• When using multiple CharliePlex FeatherWings, make sure each has a unique I2C address.
• Avoid exposing the LED matrix to mechanical stress or excessive heat.
• Use the provided library from Adafruit for easy programming and control of the LED matrix.

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

// Create the LED matrix object
Adafruit_IS31FL3731 matrix = Adafruit_IS31FL3731();

void setup() {
  Wire.begin(); // Start I2C
  if (!matrix.begin()) { // Initialize the CharliePlex matrix
    Serial.println("IS31FL3731 not found");
    while (1);
  }
  Serial.begin(9600);
  Serial.println("IS31FL3731 found!");
}

void loop() {
  matrix.setBrightness(127); // Set the brightness to a medium value
  matrix.fillScreen(0); // Clear the matrix
  for (uint8_t i=0; i<15; i++) {
    matrix.drawPixel(i, i, 50); // Draw a diagonal line
    matrix.writeDisplay(); // Update the display
    delay(100);
  }
}

Note: The above code is for demonstration purposes and assumes the use of an Arduino UNO with an I2C interface. Make sure to install the Adafruit_IS31FL3731 library before uploading the code to your board.

• LEDs Not Lighting Up: Check the power connections and ensure the Feather board is powered on.
• Dim or Flickering LEDs: Verify the brightness setting in your code and check for a stable power supply.
• I2C Communication Errors: Ensure that the SDA and SCL connections are secure and that the correct I2C address is being used.

• Double-check all connections and solder joints for any loose connections or shorts.
• Use the Serial.print statements to debug and verify that the matrix is initialized correctly.
• If using multiple CharliePlex FeatherWings, confirm that each has a unique I2C address.

Q: Can I use the CharliePlex FeatherWing with other microcontrollers besides the Feather series? A: Yes, as long as the microcontroller supports I2C communication and operates within the voltage range of the CharliePlex FeatherWing.

Q: How do I change the I2C address? A: The I2C address can be changed by soldering the ADDR jumpers on the back of the board to connect different combinations of the address pins to ground.

Q: Can I control individual LEDs? A: Yes, the library provided by Adafruit allows you to control each LED individually.

Q: Is it possible to daisy-chain multiple CharliePlex FeatherWings? A: Yes, you can daisy-chain multiple units as long as each one has a unique I2C address.