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

The Adafruit Charlieplex 9x16 Green is a compact and versatile LED matrix driver board designed to control a 9x16 grid of green LEDs, totaling 144 individual LEDs. This board utilizes the Charlieplexing technique to enable control of many LEDs with a minimal number of microcontroller pins. It is ideal for creating dynamic displays, animations, and indicators for projects where space and pin count are at a premium.

• Wearable electronics
• Small-scale message displays
• Battery-powered signs
• Decorative lighting
• Educational projects to demonstrate Charlieplexing

• Operating Voltage: 3.3V - 5V
• Maximum Current per LED: 20mA
• LED Wavelength: 565nm (Green)
• Communication Interface: I2C
• I2C Addresses: 0x70 (default) - 0x77 (selectable with solder jumpers)

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 SDA and SCL pins on your microcontroller (e.g., Arduino UNO).

3. Address Selection: If using multiple Charlieplex boards, solder the ADDR pin to select different I2C addresses from 0x70 to 0x77.

4. Programming: Use the Adafruit LED Backpack library to control the LED matrix via the I2C interface.

• Ensure that the power supply voltage does not exceed 5V to prevent damage to the LEDs.
• Limit the current per LED to 20mA or less to maintain the longevity of the LEDs.
• When daisy-chaining multiple boards, ensure that the total current does not exceed the power supply capabilities.
• Use pull-up resistors on the SDA and SCL lines if your microcontroller does not have built-in pull-ups.

#include <Wire.h>
#include <Adafruit_GFX.h>
#include <Adafruit_LEDBackpack.h>

Adafruit_9x16CharlieplexedMatrix matrix = Adafruit_9x16CharlieplexedMatrix();

void setup() {
  matrix.begin(0x70); // Start the matrix with I2C address 0x70
}

void loop() {
  matrix.clear(); // Clear the matrix display
  matrix.drawPixel(0, 0, LED_ON); // Turn on the LED at (0,0)
  matrix.writeDisplay(); // Update the display with the changes
  delay(500);
  matrix.drawPixel(0, 0, LED_OFF); // Turn off the LED at (0,0)
  matrix.writeDisplay(); // Update the display with the changes
  delay(500);
}

Ensure that the Adafruit LED Backpack 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 LEDs: Ensure that the power supply is providing sufficient voltage and that the current limiting resistors are correctly sized.
• Incorrect LED Patterns: Verify that the correct I2C address is being used in the code and that there are no soldering issues on the ADDR pins.

• Double-check wiring connections and solder joints for any cold solder or loose wires.
• Use a multimeter to verify the voltage levels at the VCC and GND pins.
• If using multiple Charlieplex boards, ensure that each board has a unique I2C address.
• Check the Adafruit LED Backpack library documentation for additional functions and examples.

Q: Can I use this board with a 3.3V system? A: Yes, the board is compatible with both 3.3V and 5V systems.

Q: How many of these boards can I chain together? A: You can chain up to 8 boards together, each with a unique I2C address.

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

Q: Can I control individual LED brightness? A: The board does not support individual LED brightness control, but you can achieve PWM-like effects through software by rapidly turning LEDs on and off.

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