Arduino-Pedal-Effects/c/bit_crusher.ino

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2022-07-18 16:23:07 +00:00
// CC-by-www.Electrosmash.com
// Based on OpenMusicLabs previous works.
/* pedalshield_uno_bit_crusher.ino reads the ADC and shift the bits creating a high distorted sound
* pressing the pushbutton_1 or 2 turns the bit shift harder or softer..
*/
//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, bit_crush_variable=0;
int counter=0;
unsigned int ADC_low, ADC_high;
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()
{
//Turn on the LED if the effect is ON.
if (digitalRead(FOOTSWITCH)) digitalWrite(LED, HIGH);
else digitalWrite(LED, LOW);
//nothing here, all happens in the Timer 1 interruption.
}
ISR(TIMER1_CAPT_vect)
{
// get ADC data
ADC_low = ADCL; // you need to fetch the low byte 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
//// All the Digital Signal Processing happens here: ////
counter++; //to save resources, the pushbuttons are checked every 10000 times.
if(counter==10000)
{
counter=0;
if (!digitalRead(PUSHBUTTON_2)) {
if (bit_crush_variable<16)bit_crush_variable=bit_crush_variable+1; //increase the vol
digitalWrite(LED, LOW); //blinks the led
}
if (!digitalRead(PUSHBUTTON_1)) {
if (bit_crush_variable>0)bit_crush_variable=bit_crush_variable-1; //decrease vol
digitalWrite(LED, LOW); //blinks the led
}
}
//The bit_crush_variable goes from 0 to 16 and the input signal is crushed in the next instruction:
input = input<<bit_crush_variable;
//write the PWM signal
OCR1AL = ((input + 0x8000) >> 8); // convert to unsigned, send out high byte
OCR1BL = input; // send out low byte
}