Difference between revisions of "S16: Mars 1"

Revision as of 03:18, 23 May 2016

Grading Criteria

Project Title

Spread Spectrum Audio Visualizer

Abstract

The main goal is to design a LED display system to visualize audio frequency spectrum. The system we designed is capable of displaying audio frequencies up to 4 kHz as we have taken 8*8 LED Matrix to display.The audio is sampled through an audio amplifier with 50dB. The signals will be converted by integrated ADC module in the LPC1578 micro controller. The FFT algorithm is implemented to convert the value from time domain to frequency domain.Extracted frequency samples are manipulated to get power spectrum and will be given to LED matrix display through I2C interface. The LED matrix display will light up horizontal(row) and vertical(column) LEDs depending on the spectral component present in it.LED Matrix X-axis (rows) correspond to frequency and Y-axis (columns) correspond to power of that frequency, taken as the complex square root of the real and imaginary parts.

Objectives & Introduction

The main objective of the project is to convert audio analog signal from time domain to frequency domain and display the frequency and amplitude using LED matrix.

• 1. The control unit is using LPC1578 SJOne board which perform the Fast Fourier Transform(FFT). It takes input from audio module and uses ADC to convert to digital signals as input of FFT module, it uses I2C bus to write LED matrix board to display.
• 2. The audio input module is Adafruit Electric Microphone Amplifier - MAX9814 with Auto Gain Control; If takes sound/audio as input and filter the noise and pass the analog signal to SJOne board.
• 3. The 8x8 LED matrix is Adafruit Bicolor LED Square Pixel Matrix with I2C Backpack.There is I2C slave chip on board so SJOne board can write the registers to light up the LED to indicate frequency and amplitude.

Team Members & Responsibilities

• Jaswanth Bhimanapalli
  • Fast Fourier Transforms(FFT) + I2C + Debugging ADC,LED Matrix issues +Video demo preparation +Testing
• Sucharitha Sirigireddy
  • Fast Fourier Transforms(FFT) + I2C + Debugging ADC,LED Matrix issues +Video demo preparation +Testing + making PPT + writing report and proposal review
• Tianran Chen
  • LED interfacing + making PPT
• Wei Liu
  • ADC interfacing + Wikipedia update + Project proposal

Schedule

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Parts List & Cost

Design & Implementation

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Hardware Design

The hardware system is composed of audio board with sensor and filters, SJOne board based on LPC1758, LED matrix board. The block diagram is shown in below.

1. Audio Sensor Board: The audio board is Adafruit AGC Electret Microphone Amplifier - MAX9814 as shown below:

The major parameters of the audio sensor board used in this project are:

• Supply Voltage: 3.3V @ 3mA current
• Output: 2Vpp on 1.25V bias
• Frequency Response: 20Hz - 20 KHz
• Programmable Attack and Release Ratio
• Automatic gain:40dB

2. SJOne Board: The SJOne board is using NXP LPC1758 microcontroller. The top view of the board is shown below: File:SJOne board.png

3. 8x8 LED Matrix Board: The led Matrix board is Adafruit Bicolor LED Square Pixel Matrix with I2C Backpack

Hardware Interface

As shown in the block diagram, the system is composed with 3 boards.

The wiring of the system is shown in below Figure.

For the audio sensor board,there are 3 pins connected to SJOne board:

• 1. GND connects to the X2 pin16(GND) in SJOne board;
• 2. VDD connects to the X2 pin17(VDD) in SJOne board.
• 3. Leave the Gain pin open to have gain as 60dB.
• 4. Connect the OUT pin to X1 pin 12(AD0.3) in SJOne board.

For the 8x8 LED matrix board, there are only 3 pins connected to SJOne board.Thanks to the “smarts” of the LED matrix backpack, this whole project requires fewer than a dozen parallel connections total:

• 1. Connect the LED matrix + pin to the SJOne Diode D1 cathord side as 5V to power up the LED board.
• 2. Connect the LED matrix – pin to X1 pin 1(GND) in SJOne board.
• 3. Connect the matrix backpack D (data) to X2 Pin 1(SDA1) in SJOne board and C (clock) pin to X2 pin 2(SCL1) in SJOne board, respectively.

Inside the SJOne board, ADC(Port 0.26)is used to sample the analog signals from audio sensor board. The converted digital signals will be 12 bits and they are passed to FFT module, after the FFT is calculated, the new values will be decoded by ARM controller and the controller will use I2C to write the registers in the LED matrix to light up the LEDs.

Software Design

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Implementation

After power up ,ADC,Timer and LED Matrix are initialized.A Queue is used to send ADC sampled data and a semaphore to communicate ADC and FFT. ADC and FFT calculations are done in separate tasks. FFT task has high priority so that once the calculations are done and data sent to LED Matrix,ADC will start conversion.ADC task starts conversion and starts timer,collects required samples and gives semaphore to FFT. Upon semaphore acquire FFT converts input samples,calculates power in each frequency and sends data to LED.

Snapshot of the main function looks as follows:

      vSemaphoreCreateBinary(fftsem);
      scheduler_add_task(new adc_h(PRIORITY_MEDIUM));
      xTaskCreate(callingFFT1,(const char*)"Task",STACK_BYTES(4096),NULL,PRIORITY_HIGH,NULL);
      scheduler_start();

Testing & Technical Challenges

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My Issue #1

Discuss the issue and resolution.

Conclusion

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Project Video

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S16: Mars 1--Spread Spectrum Audio Visualizer Video Demo https://youtu.be/wJfcZhCSe50

CMPE 244 Final Project Testing https://youtu.be/mohN_9pHpBg

Project Source Code

• Sourceforge Source Code Link

References

Acknowledgement

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References Used

List any references used in project.

https://en.wikipedia.org/wiki/Fast_Fourier_transform https://learn.adafruit.com/fft-fun-with-fourier-transforms/spectrum-analyzer https://en.wikipedia.org/wiki/Spectrum_analyzer

Appendix

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