This echo pedal creates a delayed signal which is played back multiple times, creating the sound of a repeating decaying echo.
- Potentiometer 0: Adjust the depth of the echo .
- Potentiometer 1: Not used.
- Potentiometer 2: Set the effect volume.
echo.ino:// Licensed under a Creative Commons Attribution 3.0 Unported License.
// Based on rcarduino.blogspot.com previous work.
// www.electrosmash.com/pedalshield
int in_ADC0, in_ADC1; //variables for 2 ADCs values (ADC0, ADC1)
int POT0, POT1, POT2, out_DAC0, out_DAC1; //variables for 3 pots (ADC8, ADC9, ADC10)
int LED = 3;
int FOOTSWITCH = 7;
int TOGGLE = 2;
#define MAX_DELAY 40000
uint16_t sDelayBuffer0[MAX_DELAY];
unsigned int Delay_Depth, DelayCounter = 0;
void setup()
{
//turn on the timer clock in the power management controller
pmc_set_writeprotect(false);
pmc_enable_periph_clk(ID_TC4);
//we want wavesel 01 with RC
TC_Configure(TC1,1, TC_CMR_WAVE | TC_CMR_WAVSEL_UP_RC | TC_CMR_TCCLKS_TIMER_CLOCK2);
TC_SetRC(TC1, 1, 238); // sets <> 44.1 Khz interrupt rate
TC_Start(TC1, 1);
// enable timer interrupts on the timer
TC1->TC_CHANNEL[1].TC_IER=TC_IER_CPCS;
TC1->TC_CHANNEL[1].TC_IDR=~TC_IER_CPCS;
//Enable the interrupt in the nested vector interrupt controller
//TC4_IRQn where 4 is the timer number * timer channels (3) + the channel number
//(=(1*3)+1) for timer1 channel1
NVIC_EnableIRQ(TC4_IRQn);
//ADC Configuration
ADC->ADC_MR |= 0x80; // DAC in free running mode.
ADC->ADC_CR=2; // Starts ADC conversion.
ADC->ADC_CHER=0x1CC0; // Enable ADC channels 0,1,8,9 and 10
//DAC Configuration
analogWrite(DAC0,0); // Enables DAC0
analogWrite(DAC1,0); // Enables DAC0
}
void loop()
{
//Read the ADCs
while((ADC->ADC_ISR & 0x1CC0)!=0x1CC0);// wait for ADC 0, 1, 8, 9, 10 conversion complete.
in_ADC0=ADC->ADC_CDR[7]; // read data from ADC0
in_ADC1=ADC->ADC_CDR[6]; // read data from ADC1
POT0=ADC->ADC_CDR[10]; // read data from ADC8
POT1=ADC->ADC_CDR[11]; // read data from ADC9
POT2=ADC->ADC_CDR[12]; // read data from ADC10
}
//Interrupt at 44.1KHz rate (every 22.6us)
void TC4_Handler()
{
//Clear status allowing the interrupt to be fired again.
TC_GetStatus(TC1, 1);
//Store current readings
sDelayBuffer0[DelayCounter] = (in_ADC0 + (sDelayBuffer0[DelayCounter]))>>1;
//Adjust Delay Depth based in pot0 position.
Delay_Depth =map(POT0>>2,0,2047,1,MAX_DELAY);
//Increse/reset delay counter.
DelayCounter++;
if(DelayCounter >= Delay_Depth) DelayCounter = 0;
out_DAC0 = ((sDelayBuffer0[DelayCounter]));
//Add volume feature based in POT2 position.
out_DAC0=map(out_DAC0,0,4095,1,POT2);
//Write the DACs
dacc_set_channel_selection(DACC_INTERFACE, 0); //select DAC channel 0
dacc_write_conversion_data(DACC_INTERFACE, out_DAC0); //write on DAC
dacc_set_channel_selection(DACC_INTERFACE, 1); //select DAC channel 1
dacc_write_conversion_data(DACC_INTERFACE, 0); //write on DAC
}
You can
listen this Echo effect in SoundCloud.
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