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I want to know how many samples per second the arduino due DAC can generate, I need to generate an ultrasonic signal (40Khz), the arduino due is not going to do anything else that generate this signail for a very short period of time.

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According to the datasheet:

  • 2-channel 12-bit 1 msps DAC

So it's possible to generate 1 million samples per second. Of course that kind of speed would need DMA to drive it smoothly.

Assuming you want to generate a sinewave at 40KHz you have to first ask yourself what resolution (time-wise) you want from that sinewave, since that's the frequency that you need to generate samples for. For instance, if you want 100 samples in your sine wave you'd need to generate those at 4Msps, which you can't. At 10 samples per cycle you'd have 400Ksps which is more manageable, but the quality of the sinewave would be pretty poor.

Or, if you don't need a sinewave, if a square wave would do, just use a normal digital IO pin. You can generate MHz then.

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  • I have never use any arduino board before, if i am rigth, the command to generate a signal with de DAC is analogwrite, The resolution is not a problem I beleave, do you think that comand can generate those 10 samples per cycle???
    – JPgiq
    May 11 '17 at 22:54
  • I am saying this beacause I need to keep it simple, I do not have time for getting involve with more DMA code :D
    – JPgiq
    May 11 '17 at 23:01
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With this code, the Arduino DUE was able to generate 250 samples per second approx. I tested it with a signal generator and an oscilloscope. I have found it on this web page http://www.electrosmash.com/pedalshield. All credit is for them.

Here is the code:

// 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; 

void setup()
{
  //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 and 1.  

  //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 

  //Add volume feature with POT2
  //out_DAC0=map(in_ADC0,0,4095,1,POT2);
  //out_DAC1=map(in_ADC1,0,4095,1,POT2);

  //Write the DACs
  dacc_set_channel_selection(DACC_INTERFACE, 0);       //select DAC channel 0
  dacc_write_conversion_data(DACC_INTERFACE, in_ADC0); //write on DAC
  //dacc_set_channel_selection(DACC_INTERFACE, 1);       //select DAC channel 1
  //dacc_write_conversion_data(DACC_INTERFACE, out_DAC1);//write on DAC
}

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