This effect Volume/Booster pedal. The code is similar to the Clean pedal, but adding the buttons read and volume feature:
input = map(input, -32768, +32768,-vol_variable, vol_variable);
The guitar input signal values goes from
-32768 to + +32768 . This value will be adjusted to a new value (volume) dictated by the variable vol_variable.
You can read more info about the "map" function in the Arduino forums.
note: This effect does not have OLED screen updates, because when the "map" function is used, the code goes too slow to be used the OLED in real time.*/
The PUSHBUTTON_1 and 2 adjust the volume using the "map" function. The pushbottons are read every 100 times to avoid multiple touch detections.
// CC-by-www.Electrosmash.com
/* pedalshield_mega_booster.ino reads the ADC and plays it into the PWM output.
* pressing the pushbutton_1 or 2 turns the volume up or down.
*/
#include "U8glib.h"
U8GLIB_SH1106_128X64 u8g(U8G_I2C_OPT_NO_ACK); // Display which does not send ACK
//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, vol_variable=10000;
int counter=0;
unsigned int ADC_low, ADC_high;
void setup() {
u8g.firstPage();
do {
u8g.setFont(u8g_font_helvR18r);
u8g.drawStr( 0, 30, "BOOSTER");
u8g.drawStr( 0, 60, " EFFECT");
} while( u8g.nextPage() );
//setup IO
pinMode(FOOTSWITCH, INPUT_PULLUP);
pinMode(TOGGLE, INPUT_PULLUP);
pinMode(PUSHBUTTON_1, INPUT_PULLUP);
pinMode(PUSHBUTTON_2, INPUT_PULLUP);
pinMode(LED, OUTPUT);
pinMode(6, OUTPUT); //PWM0 as output
pinMode(7, OUTPUT); //PWM1 as output
// setup ADC
ADMUX = 0x60; // left adjust, adc0, internal vcc
ADCSRA = 0xe5; // turn on adc, ck/32, auto trigger
ADCSRB = 0x00; // free running mode
DIDR0 = 0x01; // turn off digital inputs for adc0
// setup PWM
TCCR4A = (((PWM_QTY - 1) << 5) | 0x80 | (PWM_MODE << 1)); //
TCCR4B = ((PWM_MODE << 3) | 0x11); // ck/1
TIMSK4 = 0x20; // interrupt on capture interrupt
ICR4H = (PWM_FREQ >> 8);
ICR4L = (PWM_FREQ & 0xff);
DDRB |= ((PWM_QTY << 1) | 0x02); // turn on outputs
sei(); // turn on interrupts - not really necessary with arduino
}
void loop()
{
/*This effect does not have oled screen updates, when using the "map" function the
code goes too slow to be used the oled in real time.*/
//Turn on the LED if the effect is ON.
if (digitalRead(FOOTSWITCH)) digitalWrite(LED, HIGH);
else digitalWrite(LED, LOW);
}
ISR(TIMER4_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 100 times.
if(counter==100)
{
counter=0;
if (!digitalRead(PUSHBUTTON_2)) {
if (vol_variable<32768)vol_variable=vol_variable+20; //increase the vol
digitalWrite(LED, LOW); //blinks the led
}
if (!digitalRead(PUSHBUTTON_1)) {
if (vol_variable>0)vol_variable=vol_variable-20; //decrease vol
digitalWrite(LED, LOW); //blinks the led
}
}
//the amplitude of the input signal is modified following the vol_variable value
input = map(input, -32768, +32768,-vol_variable, vol_variable);
//write the PWM signal
OCR4AL = ((input + 0x8000) >> 8); // convert to unsigned, send out high byte
OCR4BL = input; // send out low byte
}