If using the LED matrix for the first time, we very strongly recommend working through that full tutorial first. This will let you test and confirm that the Matrix is properly assembled before moving on to this more advanced project.
- Connect the Arduino’s 3.3V pin both to the mic amp VCC pin and the Arduino’s AREF pin. We use one of the power rails on the breadboard to route 3.3 Volts to both locations. The AREF connection is very important — don’t overlook this!
- Connect the Arduino 5V pin to the LED matrix + pin.
- Connect Arduino GND pin to both the mic amp GND pin and the LED matrix – pin. You can use a breadboard power rail, or the Arduino has multiple GND pins available.
- Connect Arduino analog pin 0 to the mic amp OUT pin.
- Connect Arduino pins SDA and SCL to the matrix backpack D (data) and C (clock) pins, respectively. Earlier Arduino boards don’t include SDA and SCL pins — instead, use analog pins 4 and 5.
Note: the project only works with 8-bit AVR boards. It relies on a library that’s written in assembly language, and won’t compile on newer 32-bit boards like Arduino Zero or Adafruit Metro Express.