1. Sound Sensor
TYWu

2. Sound Sensor
Sound Sensor Module (Made by Seeed)

3. Sound Sensor
Schematic
D2 is useless

4. Experiments
Typical DSP (Digital Signal Processing) System

5. Experiments Echo Arduino System Integrator Arduino Sound Sensor Module
PWM
Integrator
Arduino
Sound
Sensor
Module

6. Experiments
PWM (8bits in Arduino)

7. Experiments
PWM

8. Experiments
Echo Block Diagram
Finite Impulse Response (FIR) Filter

9. Experiments Sketch #define SOUND_INPUT_PIN 0
#define SOUND_OUTPUT_PIN 5 // By PWM
#define RECORD_SIZE 500
int sound_record[RECORD_SIZE];
int delay_time_unit = 399;
float echo_sound_weight = 0.5;
int sensorValue;
int cur_idx;
int output_sound_value;
void setup() {
pinMode(SOUND_OUTPUT_PIN, OUTPUT); }

10. Experiments Sketch void loop() {
TCCR0B = TCCR0B & 0b | 0x01; // Modify the Freq. of Pin5 PWM
cur_idx++;
if(cur_idx >= RECORD_SIZE) cur_idx = 0;
sensorValue = analogRead(SOUND_INPUT_PIN); //use A0 to read the electrical signal
sound_record[cur_idx] = sensorValue / 4; // > 256
output_sound_value = 0;
int j = cur_idx - delay_time_unit;
if (j < 0) j = j + RECORD_SIZE;
output_sound_value = sound_record[cur_idx] + sound_record[j] * echo_sound_weight;
if(output_sound_value > 255) output_sound_value = 255;
analogWrite(SOUND_OUTPUT_PIN, output_sound_value);
sound_record[cur_idx] = output_sound_value; }

11. Experiments Which one? + sound_record[cur_idx] * echo_sound_weight
output *
echo_sound_weight
sound_record[cur_idx] +
output

12. Experiments FFT Spectrum Library

13. Experiments
FFT Spectrum

14. Experiments
FFT Spectrum

15. Experiments
FFT Spectrum (16*75Hz=1200Hz)

16. Experiments Sketch #include "PCD8544.h" #include <stdint.h>
#include <ffft.h>
#define IR_AUDIO 0 // ADC channel to capture
PCD8544 nokia = PCD8544(3, 4, 5, 7, 6);
volatile byte position = 0;
volatile long zero = 0;
int16_t capture[FFT_N]; /* Wave captureing buffer */
complex_t bfly_buff[FFT_N]; /* FFT buffer */
uint16_t spektrum[FFT_N/2]; /* Spectrum output buffer */
int pl = 0;
void setup() {
Serial.begin(57600);
adcInit();
adcCalb();
// establishContact(); // send a byte to establish contact until Processing respon
nokia.init();
nokia.command(PCD8544_DISPLAYCONTROL | PCD8544_DISPLAYNORMAL);
nokia.clear(); }

17. Experiments void loop() { int spek_for_draw; if (position == FFT_N)
fft_input(capture, bfly_buff);
fft_execute(bfly_buff);
fft_output(bfly_buff, spektrum);
pl = 0;
for (byte i = 0; i < 64; i++){
// Serial.print(spektrum[i],BYTE);
if (spektrum[i] > 100) {
pl = 1;
Serial.print(i, DEC);
Serial.print("=");
Serial.print(spektrum[i]); //TYWU
Serial.print(", ");
delay(1); }
for (byte i = 1; i < 64; i++){ // Skip 0 Channel
spek_for_draw = spektrum[i] / 2.5; // 0/2.5 ~ 255/2.5
if (spek_for_draw > 39) spek_for_draw = 39;
nokia.drawline(i+10, 39 - spek_for_draw, i+10, 39, BLACK);
nokia.drawstring(5, 5, " ");
nokia.display(); // Update Screen
nokia.clear(); // Clear Screen for the animation
if (pl == 1) Serial.println(" ");
position = 0;

18. Experiments void establishContact() {
while (Serial.available() <= 0) {
Serial.print('A', BYTE); // send a capital A
delay(300); }
// free running ADC fills capture buffer
ISR(ADC_vect) {
if (position >= FFT_N)
return;
capture[position] = ADC + zero;
if (capture[position] == -1 || capture[position] == 1)
capture[position] = 0;
position++;
void adcInit(){
/* REFS0 : VCC use as a ref, IR_AUDIO : channel selection, ADEN : ADC Enable, ADSC : ADC Start, ADATE : ADC Auto Trigger Enable, ADIE : ADC Interrupt Enable, ADPS : ADC Prescaler */
// free running ADC mode, f = ( 16MHz / prescaler ) / 13 cycles per conversion
ADMUX = _BV(REFS0) | IR_AUDIO; // | _BV(ADLAR);
// ADCSRA = _BV(ADSC) | _BV(ADEN) | _BV(ADATE) | _BV(ADIE) | _BV(ADPS2) | _BV(ADPS1) //prescaler 64 : Hz - 300Hz per 64 divisions
ADCSRA = _BV(ADSC) | _BV(ADEN) | _BV(ADATE) | _BV(ADIE) | _BV(ADPS2) | _BV(ADPS1) | _BV(ADPS0); // prescaler 128 : 9615 Hz Hz per 64 divisions, better for most music
sei();
void adcCalb(){
Serial.println("Start to calc zero");
long midl = 0;
// get 2 meashurment at 2 sec
// on ADC input must be NO SIGNAL!!!
for (byte i = 0; i < 2; i++)
position = 0;
delay(100);
midl += capture[0];
delay(900);
zero = -midl/2;
Serial.println("Done.");

19. Experiments Cartoon Sound #define SOUND_INPUT_PIN 0
#define SOUND_OUTPUT_PIN 5 // Pin 4 for ATMEGA 1280, Pin 5 for Arduino UNO (for PWM output)
#define RECORD_SIZE 100
char sound_record[RECORD_SIZE];
int sensorValue;
int write_idx=0, read_idx=1;
int output_sound_value;
int frequency_type = 25; // 7: 0.75 time, 10: 1 time, 15: 1.5 times, 20: two times, 25: 2.5 times
void setup() {
pinMode(SOUND_OUTPUT_PIN, OUTPUT);
// Serial.begin(9600); }

20. Experiments void loop() { TCCR0B = TCCR0B & 0b11111000 | 0x01;
// Modify the Frequency of Pin5 PWM
sensorValue = analogRead(SOUND_INPUT_PIN); //use A0 to read the electrical signal
sound_record[write_idx++] = sensorValue >> 2; // > 256
if(write_idx >= RECORD_SIZE) write_idx = 0;
//if(write_idx >= RECORD_SIZE / 2) {
if(frequency_type >= 10 || (frequency_type ==7 && write_idx % 4 != 0)) {
output_sound_value = (sound_record[read_idx - 1] +
sound_record[read_idx]) / 2;
analogWrite(SOUND_OUTPUT_PIN, output_sound_value);
sound_record[read_idx] = sound_record[read_idx++] >> 1; }

21. Experiments
if((frequency_type == 15 || frequency_type == 25) && write_idx % 2 == 0) {
output_sound_value = (output_sound_value + sound_record[read_idx]) / 2;
analogWrite(SOUND_OUTPUT_PIN, output_sound_value);
sound_record[read_idx] = sound_record[read_idx++] >> 1; }
if(frequency_type >= 20) {
sound_record[read_idx++] = output_sound_value >> 1;
if(read_idx >= RECORD_SIZE) {read_idx = 1;}