Lesson 47--Microduino Audio Spectrum & Video Output

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This course will show you how to use Microduino to get sound signal and display audio spectrum via FFT(Fast Fourier Transform) on your TV.


  • Other Hardware Equipment
Hardware needed Number Function
n3904 NPN triode One Used as an amplifier
1KΩ resistor One Current limit
330Ω resistor One Current limit
10KΩ resistor Two Current limit
100KΩ resistor Onr Current limit
2N3904 triode One Current limit
0.1uf capacitance Two Pass high frequency and stop low frequency
Breadboard One All components gather here
Breadboard jumper Several Connector
Electret microphone One Receive sound signal
AV interface display One Display spectrum
RCA wire One Video transmission line






Step 1:

First, we need an electric microphone to build a device that can receive sound signal, as follows:


Connect the output terminal to Microduino's A0 port, you can use A0 output value to judge the circuit buildup.

Step 2:

Make RCA line, connect it to Microduino. For details, please refer to Microduino video output tutorial:

Microduino Video Output

Here is the well-built circuit:


Step 3: Download the code and run. Program functions in:

1. Read data off A0 port.

2. Cut data for some time and process it with FFT.

3. Display the well-processed data in the way of scetches and lines.

4. That cycle repeats

It is displayed as follows:



You’ll see audio spectrum on displayer.