134 lines
4.4 KiB
C++
134 lines
4.4 KiB
C++
/* Variation based on the flanger from openmusiclabs.com
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this program does a flanger effect, and interpolates between samples
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for a smoother sound output. a rampwave is used to set the variable
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delay. the min and max delay times it swing between is set by MIN
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and MAX. these are in samples, divide by 31.25ksps to get ms delay
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times. the push buttons determines how much the ramp increments
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by each time. this sets the frequency of the delay sweep, which is
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min/maxed by B_MIN/B_MAX. In this variant the input signal has been
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added to the output.
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*/
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#include "mult16x8.h"
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//defining harware resources.
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#define LED 13
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#define FOOTSWITCH 12
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#define TOGGLE 2
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#define PUSHBUTTON_1 A5
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#define PUSHBUTTON_2 A4
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//defining the output PWM parameters
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#define PWM_FREQ 0x00FF // pwm frequency - 31.3KHz
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#define PWM_MODE 0 // Fast (1) or Phase Correct (0)
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#define PWM_QTY 2 // 2 PWMs in parallel
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//defining FX parameters
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#define MIN 2 // min delay of ~60us
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#define MAX 200 // max delay of ~6ms
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#define SIZE MAX+10 // data buffer size - must be more than MAX
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int buffer[SIZE]; // create a data buffer
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byte dir = 1; // keeps track of up/down counting
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unsigned int location = 0; // incoming data buffer pointer
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byte button; // button checking timer
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byte counter = 4; // button counter (and start value)
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unsigned int fractional = 0x00; // fractional sample position
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int data_buffer; // temporary data storage to give a 1 sample buffer
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int toggle_position=0;
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int counter2=0; //buttons timer counter
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void setup() {
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//setup IO
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pinMode(FOOTSWITCH, INPUT_PULLUP);
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pinMode(TOGGLE, INPUT_PULLUP);
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pinMode(PUSHBUTTON_1, INPUT_PULLUP);
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pinMode(PUSHBUTTON_2, INPUT_PULLUP);
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pinMode(LED, OUTPUT);
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// setup ADC
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ADMUX = 0x60; // left adjust, adc0, internal vcc
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ADCSRA = 0xe5; // turn on adc, ck/32, auto trigger
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ADCSRB = 0x07; // t1 capture for trigger
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DIDR0 = 0x01; // turn off digital inputs for adc0
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// setup PWM
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TCCR1A = (((PWM_QTY - 1) << 5) | 0x80 | (PWM_MODE << 1)); //
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TCCR1B = ((PWM_MODE << 3) | 0x11); // ck/1
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TIMSK1 = 0x20; // interrupt on capture interrupt
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ICR1H = (PWM_FREQ >> 8);
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ICR1L = (PWM_FREQ & 0xff);
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DDRB |= ((PWM_QTY << 1) | 0x02); // turn on outputs
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sei(); // turn on interrupts - not really necessary with arduino
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}
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void loop() {
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if (digitalRead(FOOTSWITCH)) digitalWrite(LED, HIGH);
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else digitalWrite(LED, LOW);}
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ISR(TIMER1_CAPT_vect) { // all processing happens here
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// output the last value calculated
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OCR1AL = ((data_buffer + 0x8000) >> 8); // convert to unsigned, send out high byte
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OCR1BL = data_buffer; // send out low byte
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// get ADC data
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byte temp1 = ADCL; // you need to fetch the low byte first
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byte temp2 = ADCH; // yes it needs to be done this way
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int input = ((temp2 << 8) | temp1) + 0x8000; // make a signed 16b value
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//BUTTONS
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counter2++; //to save resources, the pushbuttons are checked every 2000 times.
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if(counter2==2000)
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{
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counter2=0;
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if (!digitalRead(PUSHBUTTON_1)) {
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if (counter > MIN) counter-=1; // if not at min, decrement
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}
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if (!digitalRead(PUSHBUTTON_2)) {
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if (counter < MAX) counter+=1; // if not at max, increment
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}
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}
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// fetch/store data
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buffer[location] = input; // store current sample
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location++; // go to next sample position
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if (location >= SIZE) location = 0; // deal with buffer wrap
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int temp = location - (fractional >> 8); // find delayed sample
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if (temp < 0) temp += SIZE; // deal with buffer wrap
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int output = buffer[temp]+input; // fetch delayed sample
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temp -= 1; // find adjacent sample
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if (temp < 0) temp += SIZE; // deal with buffer wrap
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int output2 = buffer[temp]+input; // get adjacent sample
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// interpolate between adjacent samples
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int temp4; // create some temp variables
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int temp5;
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// multiply by distance to fractional position
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MultiSU16X8toH16(temp4, output, (0xff - (fractional & 0x00ff)));
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MultiSU16X8toH16(temp5, output2, (fractional & 0x00ff));
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output = temp4 + temp5; // sum weighted samples
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// save value for playback next interrupt
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data_buffer = output;
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// up or down count as necessary till MIN/MAX is reached
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if (dir) {
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if ((fractional >> 8) >= MAX) dir = 0;
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fractional += counter;
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}
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else {
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if ((fractional >> 8) <= MIN) dir = 1;
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fractional -= counter;;
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}
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}
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