user13535: Im new here. Anyone that could give a code or sample that would generate I wanted to use a frequency in range of 35k-43kHz. Please help me.

user7566: use the 'tone' function:
arduino tone function
example:
//tone(pinNumber, FrequencyInHertz);
tone(6, 35000); //generate a 35kHz tone on pin 6
delay(10);
tone(6, 43000); //generate a 43kHz tone on pin 6


user10794: The code below generates 38 kHz and modulates its duty cycle.
// Example of modulating a 38 kHz frequency duty cycle by reading a potentiometer
// Author: Nick Gammon
// Date: 24 September 2012

const byte POTENTIOMETER = A0;
const byte LED = 10;  // Timer 1 "B" output: OC1B

// Clock frequency divided by 38 kHz frequency desired
const long timer1_OCR1A_Setting = F_CPU / 38000L;

void setup() 
 {
  pinMode (LED, OUTPUT);

  // set up Timer 1 - gives us 38.005 kHz 
  // Fast PWM top at OCR1A
  TCCR1A = bit (WGM10) | bit (WGM11) | bit (COM1B1); // fast PWM, clear OC1B on compare
  TCCR1B = bit (WGM12) | bit (WGM13) | bit (CS10);   // fast PWM, no prescaler
  OCR1A =  timer1_OCR1A_Setting - 1;                 // zero relative  
  }  // end of setup

void loop()
  {
  // alter Timer 1 duty cycle in accordance with pot reading
  OCR1B = (((long) (analogRead (POTENTIOMETER) + 1) * timer1_OCR1A_Setting) / 1024L) - 1;

  // do other stuff here
  }


13535: <p>Im new here. Anyone that could give a code or sample that would generate I wanted to use a frequency in range of 35k-43kHz. Please help me.</p>
 7566: <p>use the 'tone' function:
<a href="https://www.arduino.cc/en/Reference/Tone" rel="nofollow">arduino tone function</a></p>

<p>example:</p>

<pre><code>//tone(pinNumber, FrequencyInHertz);
tone(6, 35000); //generate a 35kHz tone on pin 6
delay(10);
tone(6, 43000); //generate a 43kHz tone on pin 6
</code></pre>
 10794: <p>The code below generates 38 kHz and modulates its duty cycle.</p>

<pre><code>// Example of modulating a 38 kHz frequency duty cycle by reading a potentiometer
// Author: Nick Gammon
// Date: 24 September 2012

const byte POTENTIOMETER = A0;
const byte LED = 10;  // Timer 1 "B" output: OC1B

// Clock frequency divided by 38 kHz frequency desired
const long timer1_OCR1A_Setting = F_CPU / 38000L;

void setup() 
 {
  pinMode (LED, OUTPUT);

  // set up Timer 1 - gives us 38.005 kHz 
  // Fast PWM top at OCR1A
  TCCR1A = bit (WGM10) | bit (WGM11) | bit (COM1B1); // fast PWM, clear OC1B on compare
  TCCR1B = bit (WGM12) | bit (WGM13) | bit (CS10);   // fast PWM, no prescaler
  OCR1A =  timer1_OCR1A_Setting - 1;                 // zero relative  
  }  // end of setup

void loop()
  {
  // alter Timer 1 duty cycle in accordance with pot reading
  OCR1B = (((long) (analogRead (POTENTIOMETER) + 1) * timer1_OCR1A_Setting) / 1024L) - 1;

  // do other stuff here
  }
</code></pre>
