// CC-by-www.Electrosmash.com // Based on OpenMusicLabs previous works. /* pedalshield_uno_booster.ino reads the ADC and plays it into the PWM output. * 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, 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<> 8); // convert to unsigned, send out high byte OCR1BL = input; // send out low byte }