Question

Your employer has asked you to design a digital, programmable guitar effects pedal. The pedal
processes audio from an electric guitar to change the way it sounds. The user can configure
the pedal using software on a PC to download a new configuration to the pedal. You plan to
market this as a high-quality product for expert musicians. You expect to sell a few thousand
units each year for around $600 dollars each.
What kind of part (or parts) would you use to build the major digital parts of this system?
(For example e.g. \an FPGA", or \an embedded PC"...)

plz answer it wth all 3 reasons with proper discription

Answer 1

Use an Arduino to make your own programmable guitar pedal and add effects like distortion, fuzz, and more to your music.
Required Materials
Reference Qty Value Description Part Reference
Capacitors
C5,C2, C7, C8, C9 5 6.8n ceramic cap SR211C682MARTR1
C3, C6, C10 3 4.7u electrolytic cap ECE-A1EKA4R7
C1, C11 2 100n ceramic cap K104K10X7RF5UH5
C4 1 270p ceramic cap D271K20Y5PH63L6R
Resistors   
R12,R13, R10, R9, R6, R4, R3 7 4.7K Resistor, 1%,1/4W MFR-25FRF52-4K7
R5, R7, R8, 3 100K Resistor, 1%,1/4W MFR-25FRF52-100K
R1, R2 2 1M Resistor, 1%,1/4W MFR-25FRF52-1M
R11 1 1M2 Resistor, 1%,1/4W MFR-25FRF52-1M2
Others   
RV1 1 500K resistor trimmer 3319W-1-504
D1 1 Led 3mm blue blue led 3mm SSL-LX3044USBC
U1 1 TL972 pdip-8 op-amp rail-to-rail TL972
IC Socket 1 dip 8 socket socket dor dip8 1-2199298-2
SW1 1 3DPT footswitch 3PDT footsitch 107-SF17020F-32-21RL
SW2 1 Toggle switch SPDT toogle switch 612-100-A1111
SW3, SW4 2 Pushbutton off-on pushbutton 103-1013-EVX
Conn1,2,3,4 1 40 pin header 2.54 pitch pin header
J1, J2 2 1/4 Jack audio stereo 6.35mm jack NMJ6HCD2

How Does the Arduino Guitar Pedal Work?

The system consists of three stages:

The Input Stage: Amplifies and filters the guitar signal making it ready for the Arduino Uno ADC (Analog do Digital Converter).

Arduino Board: Takes the digitalized waveform from the ADC and does all the Digital Signal Processing (DSP) creating effects (distortion, fuzz, volume, metronome...).

The Output Stage: Once the new waveform is created, the signal is taken from the Arduino digital outputs (two PWMs combined) and prepared to be sent to the next pedal or the guitar amp.
This is how you connect the system to your amp and guitar:

The functionality is simple; one op-amp will prepare the signal to be digitized and one opamp will recover the signal from the Arduino UNO microcontroller. One ADC is used to read the guitar signal and two PWM signals are used to generate the output signal.

Input Stage: The guitar signal is amplified for better acquisition by the first op-amp which follows the MicroAmp guitar pedal design. The trimmer VR1 adjusts the gain of this amplifier from 1 to 21, so the guitar level can be optimized. The signal pass through 3 low pass filters (formed by R3&C2, R5&C4, R6&C5) that will remove the excess of high harmonics that can create aliasing during the ADC signal acquisition (fc=5KHz).Output Stage: Uses a Sallen & Key 3rd order low pass filter which removes harmonics above 5KHz. Two PWM signals are used in parallel improving the bit resolution (2x8bits). If you want to read more about the PWM audio generation read the forum topic dedicated to the PWM configuration options. There is fantastic research done by OpenMusic Labs referring to this topic.Power Supply: The pedal uses the +5V from Arduino Uno to feed the rail-to-rail operational amplifier and achieve design simplicity and maximum signal swing without clipping. A resistor divider R7&R8 generates 2.5V for virtual ground and the cap C6 remove ripple on the power line.

User Interface: The player can use 2 configurable push-buttons, 1 configurable toggle switch, 3PDT true-bypass footswitch, and a programmable LED.Arduino Uno Connectors: Pin headers will link the shield with the Arduino Uno transferring the signals and power supply.

Arduino Code for the DIY Guitar Pedal
// CC-by-www.Electrosmash.com
// Based on OpenMusicLabs previous works.
// pedalshield_uno_booster.ino: pressing the pushbutton_1 or 2 turns the volume up or down.

//defining harware resources.
#define LED 13
#define FOOTSWITCH 12
#define TOGGLE 2
#define PUSHBUTTON_1 A5
#define PUSHBUTTON_2 A4

//defining the output PWM parameters
#define PWM_FREQ 0x00FF // pwm frequency - 31.3KHz
#define PWM_MODE 0 // Fast (1) or Phase Correct (0)
#define PWM_QTY 2 // 2 PWMs in parallel

//other variables
int input, vol_variable=512;
int counter=0;
unsigned int ADC_low, ADC_high;

void setup() { //setup IO - inputs/outputs pins configurations and pull-ups
pinMode(FOOTSWITCH, INPUT_PULLUP);
pinMode(TOGGLE, INPUT_PULLUP);
pinMode(PUSHBUTTON_1, INPUT_PULLUP);
pinMode(PUSHBUTTON_2, INPUT_PULLUP);
pinMode(LED, OUTPUT);

// setup ADC- configured to be reading automatically the hole time.
ADMUX = 0x60; // left adjust, adc0, internal vcc
ADCSRA = 0xe5; // turn on adc, ck/32, auto trigger
ADCSRB = 0x07; // t1 capture for trigger
DIDR0 = 0x01; // turn off digital inputs for adc0

// setup PWM - for more info about this config check the forum.
TCCR1A = (((PWM_QTY - 1) << 5) | 0x80 | (PWM_MODE << 1)); //
TCCR1B = ((PWM_MODE << 3) | 0x11); // ck/1 TIMSK1 = 0x20; // interrupt on capture interrupt ICR1H = (PWM_FREQ >> 8);
ICR1L = (PWM_FREQ & 0xff);
DDRB |= ((PWM_QTY << 1) | 0x02); // turn on outputs
sei(); // turn on interrupts - not really necessary with arduino
}

void loop()
{
//Turn on the LED if the effect is ON.
if (digitalRead(FOOTSWITCH)) digitalWrite(LED, HIGH);
else digitalWrite(LED, LOW);
//nothing more here, all happens in the Timer 1 interruption.
}

ISR(TIMER1_CAPT_vect) //Timer 1 interruption.
{
// read the ADC input signal data: 2 bytes Low and High.
ADC_low = ADCL; // Low byte need to be fetched first
ADC_high = ADCH;
//construct the input sumple summing the ADC low and high byte.
input = ((ADC_high << 8) | ADC_low) + 0x8000; // make a signed 16b value

// The push-buttons are checked now:
counter++; //to save resources, the push-buttons are checked every 100 times.
if(counter==100)
{
counter=0;
if (!digitalRead(PUSHBUTTON_1)) {
if (vol_variable<1024) vol_variable=vol_variable+1; //increase the vol } if (!digitalRead(PUSHBUTTON_2)) { if (vol_variable>0) vol_variable=vol_variable-1; //decrease vol
}
}

//the amplitude of the signal is modified following the vol_variableusing the Arduino map fucntion
input = map(input, 0, 1024, 0, vol_variable);

//write the PWM output signal
OCR1AL = ((input + 0x8000) >> 8); // convert to unsigned, send out high byte
OCR1BL = input; // send out low byte
}