Arduino Nano INMP441: LED Spectrum Visualizer | ShillehTek

May 29, 2026 24 views

Project

Build an Arduino Nano INMP441 audio spectrum visualizer that drives a MAX7219 32x8 LED matrix using FFT, using parts available from ShillehTek.

1.5 hr Intermediate4 parts

Project Overview

Arduino Nano + INMP441 + MAX7219: Build a real-time audio spectrum visualizer where an INMP441 microphone captures music, the Arduino runs an FFT, and a MAX7219 32×8 LED matrix displays bouncing frequency bars.

The effect is similar to a classic graphic equalizer display. You can mount it on a speaker, keep it on your desk, or attach it to a guitar amp.

Time: ~1.5 hours
Skill level: Intermediate
What you will build: A 32×8 LED spectrum analyzer that visualises any audio source.

Arduino Nano audio spectrum visualizer using an INMP441 microphone and a MAX7219 4-in-1 LED matrix — INMP441 + MAX7219 + Arduino = music-reactive LED bars.

Parts List

From ShillehTek

INMP441 I²S Microphone - captures audio for FFT analysis
MAX7219 4-in-1 32×8 Dot Matrix - displays the spectrum bars
Arduino Nano V3.0 - reads the mic signal and runs the FFT
Dupont Jumper Wires - makes breadboard and module connections easy

External

5V supply (USB power works)
Audio source (speaker, phone, guitar amp)

Note: For deeper frequency analysis, use ESP32 instead of Arduino Nano. The ESP32's faster processor handles larger FFT sizes (64+ bands).

Step-by-Step Guide

Step 1 - Wire It Up

Goal: Connect the INMP441 microphone and the MAX7219 LED matrix to the Arduino Nano.

What to do: Build the circuit so the INMP441 feeds the Arduino (for sampling), and the MAX7219 is connected for display output. Follow the wiring shown in the diagrams below.

Arduino Nano connected to an INMP441 microphone module and a MAX7219 4-in-1 LED matrix for an audio spectrum visualizer — Mic + matrix + Arduino - compact build, fits in a small box.

Wiring diagram showing INMP441 microphone connections and MAX7219 LED matrix SPI pins to an Arduino Nano — INMP441 on I²S; MAX7219 on SPI (D10/11/13).

Expected result: Your Arduino, microphone module, and LED matrix are fully connected and ready for programming.

Step 2 - Install Libraries

Goal: Install the Arduino libraries required for FFT processing and MAX7219 matrix control.

What to do: In the Arduino IDE, install these libraries: arduinoFFT, MD_Parola, and MD_MAX72XX.

Expected result: The libraries are available in your IDE so the sketch compiles without missing dependency errors.

Step 3 - Upload the Sketch

Goal: Program the Arduino Nano to sample audio, compute an FFT, and draw bar heights on the 32×8 LED matrix.

What to do: Paste the code below into a new Arduino sketch, then compile and upload it to your Arduino Nano.

Code:

#include <arduinoFFT.h>
#include <MD_Parola.h>
#include <MD_MAX72xx.h>
#include <SPI.h>
#define MIC_PIN A0
#define SAMPLES 64
#define MAX_DEVICES 4
double vReal[SAMPLES], vImag[SAMPLES];
arduinoFFT FFT;
MD_Parola display(MD_MAX72XX::FC16_HW, 10, MAX_DEVICES);
const int BANDS = 16;
void setup() {
  display.begin(); display.setIntensity(2); display.displayClear();
}
void loop() {
  for (int i = 0; i < SAMPLES; i++) {
    vReal[i] = analogRead(MIC_PIN) - 512;
    vImag[i] = 0;
  }
  FFT.Windowing(vReal, SAMPLES, FFT_WIN_TYP_HAMMING, FFT_FORWARD);
  FFT.Compute(vReal, SAMPLES, FFT_FORWARD);
  FFT.ComplexToMagnitude(vReal, SAMPLES, FFT_FORWARD);
  display.displayClear();
  for (int b = 0; b < BANDS; b++) {
    int h = constrain(vReal[b + 2] / 50, 0, 8);
    // draw a vertical bar 'h' pixels tall at column b*2
    for (int y = 8 - h; y < 8; y++) {
      display.getGraphicObject()->setPoint(y, b * 2, true);
    }
  }
  display.getGraphicObject()->update();
}

Expected result: The sketch uploads successfully, and the matrix begins updating with bar-style output once audio is present.

Step 4 - Calibrate the Sensitivity

Goal: Adjust the bar scaling so typical room volume reaches a useful range on the display.

What to do: Tweak the divisor in the sketch (the line similar to vReal[b] / 50) until the bars hit full scale at your normal listening volume.

Arduino spectrum visualizer calibration screen showing the FFT scaling divisor used to set LED bar sensitivity — Tweak the divisor (line: vReal[b]/50) until bars hit full-scale at typical room volume.

Expected result: Bars rise and fall smoothly, with loud sections reaching near the top row without staying pegged at maximum.

Step 5 - Watch It Dance

Goal: Verify the visualizer responds to real music or audio.

What to do: Play audio near the microphone (from a speaker, phone, or amp) and observe the LED bars.

MAX7219 32x8 LED matrix showing animated spectrum bars reacting to music captured by an INMP441 microphone — Bars rise and fall with the music - bass on the left, treble on the right.

Expected result: The matrix shows a moving spectrum where low frequencies tend to appear toward the left and higher frequencies toward the right.

Step 6 - Where to Take It Next

Goal: Explore optional enhancements after the core build is working.

What to do: Consider extending the project with one of the ideas below.

Add peak-hold indicators that linger at the highest reading
RGB version - use a WS2812B strip for full colour spectrum
Multiple matrices side-by-side for a wider display
Wireless audio from a Bluetooth receiver → standalone reactive lamp

Expected result: You have a clear path for upgrades once the basic Arduino FFT spectrum display is stable.

Conclusion

You built an Arduino Nano audio spectrum visualizer using an INMP441 microphone and a MAX7219 32×8 LED matrix. With FFT-based frequency bands driving the display, the result is an eye-catching, sound-reactive LED bar graph.

Want the exact parts used in this build? Grab them from ShillehTek.com. If you want help customizing this project or building something for your product, check out our IoT consulting services.