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Digital Guitar Effects

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Presentation on theme: "Digital Guitar Effects"— Presentation transcript:

1 Digital Guitar Effects
Group 5 Shaun Caraway, EE Matt Evens, EE Jan Nevarez, CpE

2 Motivation and Value of Project

3 Goals Professional grade audio quality (Low noise, high resolution, etc.) Able to process a guitar signal in real-time with less than 3 ms of latency Simple user interface Include common effects used by guitarist. Reverb, distortion, etc.

4 Specifications Less than 3 ms of latency 16 bit 44.1kHz
Maximum input 2 Vpp Line level output of Vrms Headphone output impedance less than 50Ω

5 User Interface Subsystem Audio Processing Subsystem
Over all System Design User Interface Subsystem JTAG INTERFACE Audio Processing Subsystem JTAG INTERFACE LM V I2C (TW) ATMEL ATSAM3X8E MSP430G2553 SPI  WM8731 CODEC GPIO I2C (TW) I2C (TW) LM1085 5V ATMEGA328P LM V SPI DISPLAY CONTROLS

6 Algorithms

7 Algorithms Delay Used to create an “echo” type of sound.
y(n) = x(n) + [x(n – D) + G*y(n – D)] 1 x(n) S Z^-n S y(n) 1

8 Algorithms Reverb Simulates sound being played in a large room or hallway. Most intense algorithm. Pushed the limits of the ATMEL SAM 3X8E Uses parallel combination of Comb filters in series with all pass filters.

9 Algorithms Reverb All Pass Filter Comb Filter Low Pass Comb Filter
y(n) = -gx(n) + x(n – D) + gy(n – D) Comb Filter y(n) = x(n – D) + gy(n – D) Low Pass Comb Filter y(n) = x(n – D) – g2x(n – D – 1) + g2y(n – 1) + g1y(n – D) Where g = g2/(1-g1), with g < 1.0

10 Algorithms Reverb x(n) S y(n) Pre-Delay LPF1 APF1 APF2 Comb 1 Comb 2
LPFComb 3 LPFComb 4

11 Algorithms Chorus Meant to simulate multiple instruments playing together. Generally used to “thicken” the sound. y(n) = a1x(n) + Gx(n – D(n))

12 Algorithms Compressor Meant to control the dynamics of incoming signal
y(n) = x(n) + [x(n – D) + G*y(n – D)]

13 Algorithms Distortion
Used to purposefully distort the incoming guitar signal. Known as a static wave shapper. y(n) = arctan(x(n))

14 Hardware

15 User Interface Subsystem Microprocessors
MSP430G2553IPW28 Program Memory 16KB Speed 16MHz IO 24 I2C Serial Communication interface Compatible with TW Operating Voltage 3.3V ATmega328P AVR Program Memory 32 Kbytes Speed 20MHz IO 23 TW Serial Communication interface Compatible with I2C SPI Serial Communication Operating Voltage 5V

16 User Interface Subsystem Schematic

17 User Interface Subsystem Schematic
𝑅= 𝑉−𝑉 𝑓 𝑖 = 5𝑉−2.5𝑉 25𝑚𝐴 =100Ω 𝑉 𝑜𝑢𝑡 = 𝑉 𝑖𝑛 𝑅 2 𝑅 2 + 𝑅 1 =5 10𝐾 10𝐾+10𝐾 𝑉 𝑜𝑢𝑡 =2.5V

18 User Interface Subsystem PCB

19 User Interface Subsystem PCB
MSP430-JTAG connection I2C Terminal Block MSP430G2553 ATMEGA328P Controls Terminal Block LCD module Terminal Block Push Button Voltage Regulators

20 Audio Processing Subsystem
SAM3X8E Cortex-M3 Program Memory 512 Kbytes Speed 84MHz I/O Lines 103 2xTW Serial Communication interface Compatible with I2C SPI Serial Communication CPU Core ARM Operating Voltages 3.3 and 1.95 V

21 Audio Processing Subsystem Schematic

22 Audio Processing Subsystem Schematic

23 Audio Processing Subsystem Schematic
𝑓= 1 2∗𝜋∗ 10 −9 ∗1000 = Hz

24 Audio Processing Subsystem PCB

25 Audio Processing Subsystem PCB
ATMSAM3X8E JTAG-Interface/ Configuration ATMSAM3X8E Microcontroller WM8731 Audio CODEC I2C/TW Terminal Block Audio Input Line Output Headphone Output Voltage Regulator

26 Power Requierments 0.1489 0.039 0.195

27 Power Requierments LM1085 LDO regulator series V in Max 27 volts V out
Drop Out Voltage 1.3 volts I out Max 3 amps Enercell AC Adapter CAT-NO Input V AC 50/60Hz 0.5Amps Output 7.5V DC 2 Amps

28 Original DSP Subsystem

29 Original User Interface Subsystem PCB

30 Software

31 Audio Processing Software
Software Overview User Interface Allow for control Display Menu Options Signal Interrupts Audio Processing Software Model Amplifier Model Effects Allow for various parameter changes I2C Bus

32 User Interface Subsystem
Written in C language MSP430 used Energia IDE ATmega328 used Arduino IDE Push buttons generate interrupts Generates binary coded commands MSP430 Transmits to the screen controlled by the ATmega328 and the Audio Processing Subsystem over the I2C bus

33 User Interface Subsystem
Codes for the Audio Processing Codes for the Screen Subsystem

34 User Interface Subsystem
void initSetup () void I2CTransmite() void navigate() void pushButton() void menuSetup() int main() Main void initSetup () void downButton() void upButton() void forwardButton() void backButton() void whatToDo() int main() Menu void SPIConfig() void sendData() int main() I2C void init() void interrupt() int main() Buttons void initSetup () void changeDisplay() void onRecieve() int main() LCD Controller

35 Audio Processing Subsystem
Writing in C via Atmel studios Model Amplifiers/Effects Communicates to the Codec through the SPI peripheral Programs the Codec through the I2C bus Receives controller codes through I2C bus

36 Audio Processing Subsystem
void initSetup () void I2CReceive () void modelAmplifier() void modelEffects() void SPItransmit() void SPIreceive() int main() Main void I2CSPConfig() void receiveData() void transmitData() int main() I2C void SPIConfig() void tranSmiteData() void receiveData() int main() SPI void initSetup() void changeGain() Void changeInterval() int main() Effects void initSetup() void changeGain() void changeBass() void changeMid() void changeVolume() int main() Amplifier

37 Administrative

38 Distribution of Responsibilities
Shaun User Interface Hardware Audio Processing Hardware Power Jan User Interface Software Audio Processing Software Audio software Algorithm Simulation Matt Audio Codec Input Audio Codec Ouput Algorithms

39 Project Challenges Digital Signal Processing
Doing multiple double and int multiplication and division Preventing noise on the distortion effect Learning the PCB CAD software Hardware Debuging Challenges

40 Project Challenges - User Interface

41 Project Challenges - Audio Processing
JTAG Configuration – According to data sheet Signal State FWUP HI NRSTB JTAGSEL TST LO JTAGSEL JTAG Configuration – Working Signal State FWUP HI NRSTB JTAGSEL LO TST TST

42 Project Challenges - Audio Processing

43 Budget

44 Questions?

45 Copy this slide Lorem ipsum dolor sit amet, consectetuer adipiscing elit. Vivamus et magna. Fusce sed sem sed magna suscipit egestas.

46 Current Progress Hardware design 55% back off Add %’s

47 Milestones

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