View source for Lesson 47--Microduino Audio Spectrum & Video Output

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==Objective==
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.  
==Equipment==
*'''[[Microduino-Core]]'''
*'''[[Microduino-USBTTL]]'''


*Other Hardware Equipment 
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|Hardware needed||Number||Function
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|n3904 NPN triode ||One ||Used as an amplifier
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|1KΩ resistor||One ||Current limit 
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|330Ω resistor||One|| Current limit
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|10KΩ resistor ||Two|| Current limit
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|100KΩ resistor ||Onr|| Current limit
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|2N3904 triode ||One|| Current limit
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|0.1uf capacitance ||Two||Pass high frequency and stop low frequency
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|Breadboard ||One ||All components gather here 
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|Breadboard jumper ||Several||Connector 
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|Electret microphone ||One||Receive sound signal 
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|AV interface display ||One||Display spectrum 
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|RCA wire ||One||Video transmission line
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==Schematic==
[[File:AudioSpectrumAnalyzerSchmetic1.png|600px|center|thumb]]

==Program==
[https://github.com/Microduino/Microduino_Tutorials/tree/master/Microduino_Advanced/AudioSpectrumAnalyzer AudioSpectrumAnalyzer]

==Debugging==

Step 1:

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

[[File:microphoneCircuit.png|600px|center|thumb]]
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: 
[[File: microphonePhoto.png|600px|center|thumb]]

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: 
[[File: microphoneVideoOUt.png|600px|center|thumb]]

==Result==

You’ll see audio spectrum on displayer. 

=Video==
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