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

The Adafruit Warm White 15x7 CharliePlex FeatherWing is an add-on board designed for use with the Feather ecosystem of development boards. This LED matrix features a grid of 105 warm white LEDs in a 15x7 configuration, allowing for the display of text, images, and animations in a pleasing warm white hue. It utilizes Charlieplexing to minimize pin usage and simplify wiring. This component is ideal for creating wearable electronics, custom indicators, or adding a visual output to your projects.

• Wearable devices
• Custom indicators and displays
• Portable message boards
• Interactive art installations
• Educational projects teaching LED matrix control

• Operating Voltage: 3.3V to 5V
• Current Draw: ~40mA (all LEDs on)
• LED Color: Warm White
• Matrix Configuration: 15 columns x 7 rows
• Communication: I2C interface
• I2C Addresses: 0x70 (default), selectable with solder jumpers

1. Powering the FeatherWing: Connect the VIN pin to a 3.3V or 5V power supply, and the GND pin to the ground.

2. Connecting to a Feather Board: Align the headers on the FeatherWing with the corresponding sockets on the Feather board and press gently to connect.

3. I2C Communication: Connect the SDA and SCL pins to your Feather board's I2C data and clock lines.

4. Software Setup: Install the necessary libraries and upload the example code to your Feather board to start controlling the LED matrix.

• Ensure that the power supply is within the specified voltage range to prevent damage.
• When using multiple I2C devices, make sure each device has a unique I2C address.
• To avoid flickering, refresh the LED matrix display at a consistent interval.
• Consider the current draw when all LEDs are on and ensure your power supply can handle the load.

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

// Create the LED driver object
Adafruit_IS31FL3731 ledDriver;

void setup() {
  Wire.begin(); // Start I2C
  if (!ledDriver.begin()) {
    Serial.println("IS31FL3731 not found");
    while (1);
  }
  Serial.println("IS31FL3731 found!");
}

void loop() {
  // Clear the frame buffer
  ledDriver.clear();
  
  // Draw a simple pattern
  for (int i = 0; i < 15; i++) {
    for (int j = 0; j < 7; j++) {
      ledDriver.drawPixel(i, j, (i + j) % 2 ? 255 : 0);
    }
  }
  
  // Display the frame buffer on the LEDs
  ledDriver.displayFrame();
  
  delay(1000); // Wait for a second
}

• LEDs Not Lighting Up: Ensure that the FeatherWing is properly seated on the Feather board and that the power supply is correctly connected.
• Flickering LEDs: This may be due to an insufficient refresh rate. Increase the frequency at which you update the display.
• Dim LEDs: Check if the power supply is providing the correct voltage and that the current draw does not exceed the power supply's capability.

• Double-check all connections and solder joints for any loose or cold solder points.
• Verify that the I2C address is correctly set and that there are no address conflicts with other I2C devices.
• Use the Serial.println() function to output debug information to the serial monitor and help isolate issues.

Q: Can I use multiple CharliePlex FeatherWings together? A: Yes, you can connect multiple boards using different I2C addresses by adjusting the solder jumpers on the back of the boards.

Q: How do I change the brightness of the LEDs? A: The brightness can be controlled via software using the LED driver library functions.

Q: What is the maximum number of LEDs that can be lit at once? A: All 105 LEDs can be lit simultaneously, but ensure that the power supply can handle the total current draw.

Q: Can I use this FeatherWing with other microcontrollers besides Feather boards? A: Yes, as long as the microcontroller supports I2C communication and operates within the voltage range, you can use it with appropriate wiring.