echoTrek - Digital Delay / Echo - Audio Effects with Arduino

1/*****************************************************************************************************************************
2  echoTrek - 8Bit Digital Delay / LO-FI Bitcrusher / Reverse Speech DSP Pedal Effects  for Guitar, Voice, Synths, etc.
3  Works with Arduino UNO R3 / NANO / PRO MINI  - See the schematics for wiring details. By J. CesarSound - ver 1.0 - Jan/2021.
4******************************************************************************************************************************/
5
6#define  audio_in A0
7#define time_selector A3
8
9const unsigned int d_size = 1900;  //Delay memory buffer size
10unsigned int val, d_val, d_time;
11int i, j;
12byte  count = 2;
13bool rev = 0;
14char delay_data[d_size + 1] = { NULL };  //Delay  memory buffer
15char delay_data_1[d_size + 1] = { NULL };  //Delay memory buffer
16  
17
18void setup() {
19  pinMode(time_selector, INPUT_PULLUP);
20  DDRD = B00000010;
21  DDRB = B11100000;
22  InitTimer1();           //Set up timer 1 for 16.384kHz
23  setPwmFrequency(5, 1);  //function for setting PWM High frequency 62.475kHz on  pin D5
24  analogReference(INTERNAL);   //Use 1.1v aref voltage.
25  up_time();
26}
27
28void  loop() {
29  if (digitalRead(time_selector) == LOW) {
30    up_time();
31    PORTB  = B11100000;   //make pin 13 high and power on the led when pushbutton is pressed
32    while (digitalRead(time_selector) == LOW);
33  } else PORTB = B11000000;   //make  pin 13 low and power off the led pushbutton is released
34  if (rev) PORTD = B00000000;  else PORTD = B00000010;   //Reverse speech sampler indication TX Led power on
35}
36
37void  sampling() {
38  val = map(analogRead(audio_in), 0, 900, 0, 255);
39  delay_sound();
40  analogWrite(5, d_val);
41}
42
43void delay_sound() {
44  i = i + 1; if (i  > d_time) i = 0;
45  delay_data[i] = val;
46  if (i == d_time) j = 0;
47  delay_data_1[i]  = delay_data[i];
48  j = j + 1; if (j > d_time) j = 0;
49  if (!rev) d_val = delay_data_1[j];
50  if (rev) d_val = delay_data_1[d_time - j];
51}
52
53void up_time() {
54  noInterrupts();
55  count++;
56  if (count > 7)
57    count = 1;
58  delay(20);
59
60  switch  (count)  {
61    case 1:
62      d_time = 400; rev = 0; //63ms
63      break;
64    case 2:
65      d_time = 700; //110ms
66      break;
67    case 3:
68      d_time  = 1000; //158ms
69      break;
70    case 4:
71      d_time = 1300; //205ms
72      break;
73    case 5:
74      d_time = 1600; //253ms
75      break;
76    case 6:
77      d_time = 1900; //300ms
78      break;
79    case 7:
80      d_time  = 1500; rev = 1; //Reverse speech
81      break;
82  } interrupts();
83}
84
85//Set  up timer 1 for 16.384kHz (975)
86void InitTimer1() {
87  cli(); //Disable global  interrupts
88  TCCR1A = 0; //Reset Timer 1 Counter Control Register A
89  TCCR1B  = 0; //Reset Timer 1 Counter Control Register B
90  TCNT1  = 0; //initialize counter  value to 0
91  OCR1A = 975; //Set Timer 1 to desired frequency: 16384Hz (16,000,000  / 16384) - 1 = 975
92  //Turn on CTC (clear timer on compare match) mode:
93  TCCR1B  |= (1 << WGM12);
94  TCCR1B |= (1 << CS10); //CS10 Prescalar = 1 (no prescalar  used); CS11 Prescalar = 8
95  TIMSK1 |= (1 << OCIE1A); //Enable timer interrupt
96  sei(); //Enable interrupts
97}
98
99ISR(TIMER1_COMPA_vect) {
100  sampling();
101}
102
103//PWM  62.475kHz high frequency DAC for pins 5 & 6 (others are 32k)
104void setPwmFrequency(int  pin, int divisor) {
105  byte mode;
106  if (pin == 5 || pin == 6 || pin == 9 ||  pin == 10) {
107    switch (divisor) {
108      case 1: mode = 0x01; break;
109      case 8: mode = 0x02; break;
110      case 64: mode = 0x03; break;
111      case  256: mode = 0x04; break;
112      case 1024: mode = 0x05; break;
113      default:  return;
114    }
115    if (pin == 5 || pin == 6) {
116      TCCR0B = TCCR0B & 0b11111000  | mode;
117    } else {
118      TCCR1B = TCCR1B & 0b11111000 | mode;
119    }
120  } else if (pin == 3 || pin == 11) {
121    switch (divisor) {
122      case 1:  mode = 0x01; break;
123      case 8: mode = 0x02; break;
124      case 32: mode  = 0x03; break;
125      case 64: mode = 0x04; break;
126      case 128: mode = 0x05;  break;
127      case 256: mode = 0x06; break;
128      case 1024: mode = 0x07; break;
129      default: return;
130    }
131    TCCR2B = TCCR2B & 0b11111000 | mode;
132  }
133}