Arduino-Pedal-Effects/c/New Effects PedalSHIELD UNO/UpDown/UpDown.ino

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2022-07-18 16:23:07 +00:00
/*
Based on the 'stomp_updown" from openmusiclabs.com
this program plays through a sample buffer, first forward at
double rate, and then backwards at single rate. it changes
direction at the buffer boundary.
*/
//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
#define SIZE 1000 // buffer size, make lower if it clicks
int buffer[SIZE]; // data buffer
unsigned int location = 0; // current buffer location
unsigned int offset = 0; // distance to current location
byte dir = 0; // direction of travel in buffer
int data_buffer = 0x8000;
void setup() {
//setup IO
pinMode(FOOTSWITCH, INPUT_PULLUP);
pinMode(TOGGLE, INPUT_PULLUP);
pinMode(PUSHBUTTON_1, INPUT_PULLUP);
pinMode(PUSHBUTTON_2, INPUT_PULLUP);
pinMode(LED, OUTPUT);
// setup ADC
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
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() {
}
ISR(TIMER1_CAPT_vect) { // all processing happens here
// output the last value calculated
OCR1AL = ((data_buffer + 0x8000) >> 8); // convert to unsigned, send out high byte
OCR1BL = data_buffer; // send out low byte
// get ADC data
byte temp1 = ADCL; // you need to fetch the low byte first
byte temp2 = ADCH; // yes it needs to be done this way
int input = ((temp2 << 8) | temp1) + 0x8000; // make a signed 16b value
buffer[location] = input; // store current sample
location++; // go to next location
if (location >= SIZE) location = 0; // deal with boundary
unsigned int temp = location + offset; // find playback location
if (temp >= SIZE) temp -= SIZE; // boundary wrap
data_buffer = buffer[temp]; // fetch sample
if (dir) { // increment until at buffer boundary
if (offset >= (SIZE - 4)) {
dir = 0;
offset--;
}
else offset++;
}
else { // decrement till reaching boundary from other side
if (offset <= 4) {
dir = 1;
offset--;
}
else offset -= 2;
}
}