The CCP module is available with a number of dsPIC30/33 and PIC24 MCUs. mikroPascal PRO for dsPIC30/33 and PIC24 provides a library which simplifies using of the PWM HW Module.

  Important : PWM module uses either Timer2 or Timer3 module.

Library Routines

• PWM_Init
• PWM_Set_Duty
• PWM_Start
• PWM_Stop

PWM_Init

// Initializes the PWM module at 5KHz, channel 1, no clock prescale, timer2 :
var pwm_period1 : word;
...
pwm_period1 := PWM_Init(5000, 1, 0, 2);

PWM_Set_Duty

// Set channel 1 duty ratio to 50%:
var pwm_period1 : word;
...
PWM_Set_Duty(pwm_period1 div 2, 1);

PWM_Start

// start PWM at channel 1
PWM_Start(1);

PWM_Stop

// stop PWM at channel 1
PWM_Stop(1);

Library Example

The example changes PWM duty ratio on channels 1 and 2 continuously. If LEDs are connected to channels 1 and 2, a gradual change of emitted light will be noticeable.

Copy Code To Clipboard

program Pwm_Demo;
var current_duty, old_duty, current_duty1, old_duty1 : word;
    pwm_period1, pwm_period2 : word;

procedure InitMain();
begin
  ADPCFG := 0xFFFF;                           //
  TRISB := 0xFFFF;                            // configure PORTB pins as input
  PORTD := 0;                                 // set PORTD to 0
  TRISD := 0;                                 // designate PORTD pins as output
end;

begin
  InitMain();
  current_duty  := 16;                        // initial value for current_duty
  current_duty1 := 16;                        // initial value for current_duty1

  pwm_period1 := PWM_Init(5000 , 1, 1, 2);
  pwm_period2 := PWM_Init(10000, 2, 1, 3);

  PWM_Start(1);
  PWM_Start(2);

  PWM_Set_Duty(current_duty,  1);            // Set current duty for PWM1
  PWM_Set_Duty(current_duty1, 2);            // Set current duty for PWM2

  while (TRUE) do                                // endless loop
    begin
      if RB0_bit = 1 then                        // button on RB0 pressed
        begin
          Delay_ms(20);
          Inc(current_duty);                     // increment current_duty
          if (current_duty > pwm_period1) then   // if we increase current_duty greater then possible pwm_period1 value
            current_duty := 0;                   // reset current_duty value to zero

          PWM_Set_Duty(current_duty,  1);        // set newly acquired duty ratio
        end;

      if RB1_bit = 1 then                        // button on RB1 pressed
        begin
          Delay_ms(20);
          Dec(current_duty);                     // decrement current_duty
          if (current_duty > pwm_period1) then   // if we decrease current_duty greater then possible pwm_period1 value (overflow)
            current_duty := pwm_period1;         // set current_duty to max possible value

          PWM_Set_Duty(current_duty,  1);        // set newly acquired duty ratio
        end;

      if RB2_bit = 1 then                        // button on RB2 pressed
        begin
          Delay_ms(20);
          Inc(current_duty1);                    // increment current_duty1
          if (current_duty1 > pwm_period2) then  // if we increase current_duty1 greater then possible pwm_period2 value
            current_duty1 := 0;                  // reset current_duty1 value to zero

          PWM_Set_Duty(current_duty1,  2);       // set newly acquired duty ratio
        end;

      if RB3_bit = 1 then                        // button on RB3 pressed
        begin
          Delay_ms(20);
          Dec(current_duty1);                    // decrement current_duty1
          if (current_duty1 > pwm_period2) then  // if we decrease current_duty1 greater then possible pwm_period1 value (overflow)
            current_duty1 := pwm_period2;        // set current_duty to max possible value

          PWM_Set_Duty(current_duty1,  2);
        end;

      Delay_ms(5);                               // slow down change pace a little
    end;
end.	

HW Connection

PWM demonstration

Want more examples and libraries? 
Find them on