# Mini LED Matrix Audio Visualizer
## Overview
https://youtu.be/LPXLpRKf-MI
In this project, you'll learn how to build an audio reactive LED matrix using the 13x9 IS31FL3741 LED matrix and Feather Sense nRF52840 board with CircuitPython.
The Feather Sense nRF52840 features a built-in PDM MEMs microphone for audio input. Audio is sampled via the onboard PDM microphone. The sampled data is then visualized with color.
The 3D printed case houses the two boards and snap fits for an easy assembly. The case features a built-in button presser for using the reset button without having to take it apart. The LED matrix and Feather are secured to a PCB bracket with hardware screws and nuts.
## Prerequisite Guides
Take a moment to review the following guides.
- [Adafruit Feather nRF52840 Sense](https://learn.adafruit.com/adafruit-feather-sense)
- [Adafruit IS31FL3741](https://learn.adafruit.com/adafruit-is31fl3741)
- [ulab: Crunch numbers fast in CircuitPython](https://learn.adafruit.com/ulab-crunch-numbers-fast-with-circuitpython)
## Parts
### Adafruit Feather nRF52840 Sense
[Adafruit Feather nRF52840 Sense](https://www.adafruit.com/product/4516)
The **Adafruit Feather Bluefruit Sense** takes our popular [Feather nRF52840 Express](https://www.adafruit.com/product/4062) and adds a smorgasbord of sensors to make a great wireless sensor platform. This Feather microcontroller comes with Bluetooth® Low Energy and...
Out of Stock
[Buy Now](https://www.adafruit.com/product/4516)
[Related Guides to the Product](https://learn.adafruit.com/products/4516/guides)
### Adafruit IS31FL3741 13x9 PWM RGB LED Matrix Driver
[Adafruit IS31FL3741 13x9 PWM RGB LED Matrix Driver](https://www.adafruit.com/product/5201)
Add a splash of RGB LEDs to a project you're working on, with this adorable 13x9 RGB LED matrix breakout. It features -- no surprise -- 117 RGB LEDs, each one 2x2mm in size, in a 13x9 grid with 3mm pitch spacing.
[Unlike our 8x8 dotstar...](https://www.adafruit.com/product/3444)
In Stock
[Buy Now](https://www.adafruit.com/product/5201)
[Related Guides to the Product](https://learn.adafruit.com/products/5201/guides)
### STEMMA QT / Qwiic JST SH 4-pin to Premium Male Headers Cable
[STEMMA QT / Qwiic JST SH 4-pin to Premium Male Headers Cable](https://www.adafruit.com/product/4209)
This 4-wire cable is a little over 150mm / 6" long and fitted with JST-SH female 4-pin connectors on one end and premium Dupont male headers on the other. Compared with the chunkier JST-PH these are 1mm pitch instead of 2mm, but still have a nice latching feel, while being easy to insert...
Out of Stock
[Buy Now](https://www.adafruit.com/product/4209)
[Related Guides to the Product](https://learn.adafruit.com/products/4209/guides)
### Silicone Cover Stranded-Core Ribbon Cable - 10 Wire 1 Meter Long
[Silicone Cover Stranded-Core Ribbon Cable - 10 Wire 1 Meter Long](https://www.adafruit.com/product/3890)
For those who are fans of our silicone-covered wires, but are always looking to _up their wiring game_. We now have **Silicone Cover Ribbon cables!** These may look _a lot_ like
In Stock
[Buy Now](https://www.adafruit.com/product/3890)
[Related Guides to the Product](https://learn.adafruit.com/products/3890/guides)
### Black Nylon Machine Screw and Stand-off Set – M2.5 Thread
[Black Nylon Machine Screw and Stand-off Set – M2.5 Thread](https://www.adafruit.com/product/3299)
Totaling 380 pieces, this **M2.5 Screw Set** is a must-have for your workstation. You'll have enough screws, nuts, and hex standoffs to fuel your maker tendencies for days on end! M2.5 size screws fit almost all of the Adafruit breakout/dev board mounting holes...
In Stock
[Buy Now](https://www.adafruit.com/product/3299)
[Related Guides to the Product](https://learn.adafruit.com/products/3299/guides)
# Mini LED Matrix Audio Visualizer
## Circuit Diagram
The diagram below provides a visual reference for wiring of the components. This diagram was created using the software package [Fritzing](http://fritzing.org/download/).
## Adafruit Library for Fritzing
Use Adafruit's Fritzing parts library to create circuit diagrams for your projects. Download the library or just grab individual parts. Get the library and parts from [GitHub - Adafruit Fritzing Parts](https://github.com/adafruit/Fritzing-Library/tree/master/parts).
## Wiring the IS31FL3741 Display to the Adafruit Feather Sense
- **SDA** from Feather to **SDA** on IS31FL3741
- **SCL** from Feather to **SCL** on IS31FL3741
- **3V** from Feather to **VCC** on IS31FL3741
- **GND** from Feather to **GND** on IS31FL3741
# Mini LED Matrix Audio Visualizer
## CircuitPython on Feather Sense
[CircuitPython](https://github.com/adafruit/circuitpython) is a derivative of [MicroPython](https://micropython.org) designed to simplify experimentation and education on low-cost microcontrollers. It makes it easier than ever to get prototyping by requiring no upfront desktop software downloads. Simply copy and edit files on the **CIRCUITPY** drive to iterate.
The following instructions will show you how to install CircuitPython. If you've already installed CircuitPython but are looking to update it or reinstall it, the same steps work for that as well!
## Set up CircuitPython Quick Start!
Follow this quick step-by-step for super-fast Python power :)
[Download the latest version of CircuitPython for this board via circuitpython.org](https://circuitpython.org/board/feather_bluefruit_sense/)
**Click the link above to download the latest UF2 file.**
Download and save it to your desktop (or wherever is handy).
Plug your Feather Sense into your computer using a known-good USB cable.
**A lot of people end up using charge-only USB cables and it is very frustrating! So make sure you have a USB cable you know is good for data sync.**
Double-click the **Reset** button next to the USB connector on your board, and you will see the NeoPixel RGB LED turn green (identified by the arrow in the image). If it turns red, check the USB cable, try another USB port, etc. **Note:** The little red LED next to the USB connector will pulse red. That's ok!
If double-clicking doesn't work the first time, try again. Sometimes it can take a few tries to get the rhythm right!
You will see a new disk drive appear called **FTHRSNSBOOT**.
Drag the **adafruit\_circuitpython\_etc.uf2** file to **FTHRSNSBOOT****.**
The LED will flash. Then, the **FTHRSNSBOOT** drive will disappear and a new disk drive called **CIRCUITPY** will appear.
That's it, you're done! :)
Warning:
# Mini LED Matrix Audio Visualizer
## Code the Waterfall Visualizer
Once you've finished setting up your Feather nRF52840 Sense with CircuitPython, you can access the code and necessary libraries by downloading the Project Bundle.
To do this, click on the ** Download Project Bundle** button in the window below. It will download as a zipped folder.
https://github.com/adafruit/Adafruit_Learning_System_Guides/blob/main/Feather_Sense_Audio_Visualizer_13x9_RGB_LED_Matrix/waterfall_visualizer/code.py
## Upload the Code and Libraries to the Feather nRF52840 Sense
After downloading the Project Bundle, plug your Feather nRF52840 Sense into the computer's USB port. You should see a new flash drive appear in the computer's File Explorer or Finder (depending on your operating system) called **CIRCUITPY**. Unzip the folder and copy the following items to the Feather nRF52840 Sense's **CIRCUITPY** drive.
- **lib** folder
- **code.py**
Your Feather nRF52840 Sense **CIRCUITPY ** drive should look like this after copying the lib folder and the **code.py** file.
## How the CircuitPython Code Works
The code is a port of the [Waterfall Spectrum Analyzer CircuitPython code](https://learn.adafruit.com/ulab-crunch-numbers-fast-with-circuitpython/fft-example-waterfall-spectrum-analyzer) written by Jeff Epler for the [ulab: Crunch Numbers Fast in CircuitPython Learn Guide](https://learn.adafruit.com/ulab-crunch-numbers-fast-with-circuitpython/overview). Be sure to check out that guide for more information on the ulab CircuitPython library.
The main portion of the code remains the same. Audio is sampled via the onboard PDM microphone. The sampled data is then visualized with color. The difference is that instead of displaying that visualization with a screen, as seen on the CLUE board, it is displayed with the LED's on the matrix.
```python
# setup for onboard mic
mic = audiobusio.PDMIn(board.MICROPHONE_CLOCK, board.MICROPHONE_DATA,
sample_rate=16000, bit_depth=16)
# use some extra sample to account for the mic startup
samples_bit = array.array('H', [0] * (fft_size+3))
# sends visualized data to the RGB matrix with colors
def waves(data, y):
offset = max(0, (13-len(data))//2)
for x in range(min(13, len(data))):
is31.pixel(x+offset, y, heatmap[int(data[x])])
```
In the loop, you'll find the `ulab` CircuitPython library in action, using `numpy` to crunch the sampled data into a pretty, colorful light show.
```python
while True:
# record the audio sample
mic.record(samples_bit, len(samples_bit))
# send the sample to the ulab array
samples = np.array(samples_bit[3:])
# creates a spectogram of the data
spectrogram1 = spectrogram(samples)
# spectrum() is always nonnegative, but add a tiny value
# to change any zeros to nonzero numbers
spectrogram1 = np.log(spectrogram1 + 1e-7)
spectrogram1 = spectrogram1[1:(fft_size//2)-1]
# sets range of the spectrogram
min_curr = np.min(spectrogram1)
max_curr = np.max(spectrogram1)
# resets values
if max_curr > max_all:
max_all = max_curr
else:
max_curr = max_curr-1
min_curr = max(min_curr, 3)
# stores spectrogram in data
data = (spectrogram1 - min_curr) * (51. / (max_all - min_curr))
# sets negative numbers to zero
data = data * np.array((data > 0))
# resets y
y = scroll_offset
# runs waves to write data to the LED's
waves(data, y)
# updates scroll_offset to move data along matrix
scroll_offset = (y + 1) % 9
# writes data to the RGB matrix
is31.show()
```
### Need for Speed
It's important for data visualizations to be as speedy and reactive as possible for the best effect. To do this for the IS31FL3741 matrix, I2C is overclocked to communicate using 1 MHz speed. Additionally, the FFT data sample size is set to 64.
```python
# Manually declare I2c (not board.I2C()) to access 1 MHz speed for
i2c = busio.I2C(board.SCL, board.SDA, frequency=1000000)
# Declare is31 w/buffering preferred (low RAM will fall back on unbuffered)
is31 = Adafruit_RGBMatrixQT(i2c, allocate=adafruit_is31fl3741.PREFER_BUFFER)
# In buffered mode, MUST use show() to refresh matrix (see line 94)
# size of the FFT data sample
fft_size = 64
```
### All the Colors
After speed, the colors used to visualize the data come into play. The selected gradient in the code is a rainbow effect ranging from purple to red through the color spectrum. You can experiment with creating your own gradients too. There are quite a few tools available online for this. For this project, [colordesigner.io](https://colordesigner.io/gradient-generator) was used.
The color gradient is stored in the `heatmap` array and consists of 52 hexadecimal color codes.
```python
# array of colors for the LEDs
# goes from purple to red
# gradient generated using https://colordesigner.io/gradient-generator
heatmap = [0xb000ff,0xa600ff,0x9b00ff,0x8f00ff,0x8200ff,
0x7400ff,0x6500ff,0x5200ff,0x3900ff,0x0003ff,
0x0003ff,0x0047ff,0x0066ff,0x007eff,0x0093ff,
0x00a6ff,0x00b7ff,0x00c8ff,0x00d7ff,0x00e5ff,
0x00e0ff,0x00e6fd,0x00ecf6,0x00f2ea,0x00f6d7,
0x00fac0,0x00fca3,0x00fe81,0x00ff59,0x00ff16,
0x00ff16,0x45ff08,0x62ff00,0x78ff00,0x8bff00,
0x9bff00,0xaaff00,0xb8ff00,0xc5ff00,0xd1ff00,
0xedff00,0xf5eb00,0xfcd600,0xffc100,0xffab00,
0xff9500,0xff7c00,0xff6100,0xff4100,0xff0000,
0xff0000,0xff0000]
```
# Mini LED Matrix Audio Visualizer
## Code the Audio Spectrum Light Show
Once you've finished setting up your Feather nRF52840 Sense with CircuitPython, you can access the code and necessary libraries by downloading the Project Bundle.
To do this, click on the ** Download Project Bundle** button in the window below. It will download as a zipped folder.
https://github.com/adafruit/Adafruit_Learning_System_Guides/blob/main/Feather_Sense_Audio_Visualizer_13x9_RGB_LED_Matrix/audio_spectrum_lightshow/code.py
## Upload the Code and Libraries to the Feather nRF52840 Sense
After downloading the Project Bundle, plug your Feather nRF52840 Sense into the computer's USB port. You should see a new flash drive appear in the computer's File Explorer or Finder (depending on your operating system) called **CIRCUITPY**. Unzip the folder and copy the following items to the Feather nRF52840 Sense's **CIRCUITPY** drive.
- **lib** folder
- **code.py**
Your Feather nRF52840 Sense **CIRCUITPY ** drive should look like this after copying the lib folder and the **code.py** file.
# Mini LED Matrix Audio Visualizer
## 3D Printing
## CAD Parts List
STL files for 3D printing are oriented to print "as-is" on FDM style machines. Parts are designed to 3D print without any support material. Original design source may be downloaded using the links below:
- case.stl
- pcb-mount.stl
- cover.stl
[cad-files.zip](https://cdn-learn.adafruit.com/assets/assets/000/104/929/original/cad-files.zip?1633024130)
[STLs.zip](https://cdn-learn.adafruit.com/assets/assets/000/104/930/original/STLs.zip?1633024236)
## CAD Assembly
The IS31FL3741 and Feather Sense are secured to the PCB mount using 8x M2.5 x 10mm screws and hex nuts. The PCB mount is secured to the case with M3 x 6mm long screws. The cover snap fits on to the back of the case.
## Slicing Parts
No supports are required. Slice with setting for PLA material.
The parts were sliced using CURA using the slice settings below.
- PLA filament 220c extruder
- 0.2 layer height
- 10% gyroid infill
- 60mm/s print speed
- 60c heated bed
## Design Source Files
The project assembly was designed in Fusion 360. This can be downloaded in different formats like STEP, STL and more. Electronic components like Adafruit's board, displays, connectors and more can be downloaded from the [Adafruit CAD parts GitHub Repo](https://github.com/adafruit/Adafruit_CAD_Parts).
# Mini LED Matrix Audio Visualizer
## Assembly
## Hardware for PCBs
Use the following hardware to secure the LED matrix and Feather Sense to the PCB Mount.
- 8x M2.5 x 10mm long screws
- 8x M2.5 hex nuts
## Install LED Matrix
Place the LED matrix over the PCB mounts with matching standoffs. Insert the M2.5 x 10mm long screws through the mounting holes and standoffs.
## Secure LED Matrix
Use hex nuts to secure the LED matrix to the PCB mount. Reference the photos for correct orientation.
## Install and Secure Feather
Place the Feather Sense over the remaining standoffs on the PCB mount. Line up the mounting holes and insert M2.5 x 10mm long screws through the holes. Use M2.5 hex nuts to secure the Feather to the PCB mount.
## Install PCB Mount to Case
Orient the tabs from PCB mount with standoffs in the Case. Use M3 x 6mm screws to secure the PCB mount to the case.
## Installed PCB Mount
Place the PCB mount into the case with the mounting tabs lined up with the standoffs.
## Secure PCB Mount to Case
Insert and fasten M3 x 6mm long screws through the mounting tabs. The threads of the screw should self tap into the standoffs in the case.
## Install Cover
The back cover is symmetrical so it can be installed in either orientation. Place the cover over the case and firmly press together to snap fit shut.
## Final Build
Congratulations on building your Mini LED matrix audio visualize!
## Featured Products
### Adafruit Feather nRF52840 Sense
[Adafruit Feather nRF52840 Sense](https://www.adafruit.com/product/4516)
The **Adafruit Feather Bluefruit Sense** takes our popular [Feather nRF52840 Express](https://www.adafruit.com/product/4062) and adds a smorgasbord of sensors to make a great wireless sensor platform. This Feather microcontroller comes with Bluetooth® Low Energy and...
Out of Stock
[Buy Now](https://www.adafruit.com/product/4516)
[Related Guides to the Product](https://learn.adafruit.com/products/4516/guides)
### Adafruit IS31FL3741 13x9 PWM RGB LED Matrix Driver
[Adafruit IS31FL3741 13x9 PWM RGB LED Matrix Driver](https://www.adafruit.com/product/5201)
Add a splash of RGB LEDs to a project you're working on, with this adorable 13x9 RGB LED matrix breakout. It features -- no surprise -- 117 RGB LEDs, each one 2x2mm in size, in a 13x9 grid with 3mm pitch spacing.
[Unlike our 8x8 dotstar...](https://www.adafruit.com/product/3444)
In Stock
[Buy Now](https://www.adafruit.com/product/5201)
[Related Guides to the Product](https://learn.adafruit.com/products/5201/guides)
### Silicone Cover Stranded-Core Ribbon Cable - 10 Wire 1 Meter Long
[Silicone Cover Stranded-Core Ribbon Cable - 10 Wire 1 Meter Long](https://www.adafruit.com/product/3890)
For those who are fans of our silicone-covered wires, but are always looking to _up their wiring game_. We now have **Silicone Cover Ribbon cables!** These may look _a lot_ like
In Stock
[Buy Now](https://www.adafruit.com/product/3890)
[Related Guides to the Product](https://learn.adafruit.com/products/3890/guides)
### STEMMA QT / Qwiic JST SH 4-pin to Premium Male Headers Cable
[STEMMA QT / Qwiic JST SH 4-pin to Premium Male Headers Cable](https://www.adafruit.com/product/4209)
This 4-wire cable is a little over 150mm / 6" long and fitted with JST-SH female 4-pin connectors on one end and premium Dupont male headers on the other. Compared with the chunkier JST-PH these are 1mm pitch instead of 2mm, but still have a nice latching feel, while being easy to insert...
Out of Stock
[Buy Now](https://www.adafruit.com/product/4209)
[Related Guides to the Product](https://learn.adafruit.com/products/4209/guides)
### Black Nylon Machine Screw and Stand-off Set – M2.5 Thread
[Black Nylon Machine Screw and Stand-off Set – M2.5 Thread](https://www.adafruit.com/product/3299)
Totaling 380 pieces, this **M2.5 Screw Set** is a must-have for your workstation. You'll have enough screws, nuts, and hex standoffs to fuel your maker tendencies for days on end! M2.5 size screws fit almost all of the Adafruit breakout/dev board mounting holes...
In Stock
[Buy Now](https://www.adafruit.com/product/3299)
[Related Guides to the Product](https://learn.adafruit.com/products/3299/guides)
## Related Guides
- [Adafruit Feather nRF52840 Sense](https://learn.adafruit.com/adafruit-feather-sense.md)
- [Adafruit IS31FL3741](https://learn.adafruit.com/adafruit-is31fl3741.md)
- [LED Protest Sign](https://learn.adafruit.com/led-protest-sign.md)
- [Circle of Fifths Euclidean Synth with synthio and CircuitPython](https://learn.adafruit.com/circle-of-fifths-euclidean-synth-with-synthio-and-circuitpython.md)
- [Adafruit LSM6DS33 6-DoF IMU Breakout](https://learn.adafruit.com/lsm6ds33-6-dof-imu-accelerometer-gyro.md)
- [Animating Animatronics](https://learn.adafruit.com/animating-animatronics.md)
- [Raspberry Pi HQ Camera Case](https://learn.adafruit.com/raspberry-pi-hq-camera-case.md)
- [Programmable Wireless BLE Gesture Mouse](https://learn.adafruit.com/ble-wireless-gesture-mouse.md)
- [Light-Up Reactive Ukulele](https://learn.adafruit.com/light-up-reactive-ukulele.md)
- [PyPortal Wall Mount](https://learn.adafruit.com/pyportal-wall-mount.md)
- [Robotic AI Bear using ChatGPT](https://learn.adafruit.com/robotic-ai-bear-using-chatgpt.md)
- [Introducing Adafruit Feather](https://learn.adafruit.com/adafruit-feather.md)
- [Numpad 4000 Mechanical Keyswitch Data Entry Device](https://learn.adafruit.com/numpad-4000-mechanical-keyswitch-data-entry-device.md)
- [Compost Friend!](https://learn.adafruit.com/compost-optimization-machine.md)
- [PyPortal Titano Weather Station](https://learn.adafruit.com/pyportal-titano-weather-station.md)
- [Sketch Drawing Toy with CircuitPython](https://learn.adafruit.com/sketch-drawing-toy.md)
- [BLE Vibration Bracelet](https://learn.adafruit.com/ble-vibration-bracelet.md)