SOFT PWM For MikroC For PIC PIC12F675

[asking]

Hello friends,

I have small application of Generating 38KHZ Frequency for IR Application. I want to use PIC12F675 and it doesn't have Hardware CCP Module inside the micro controller so i want to use Soft PWM For generating PWM Signal. I searched PIC Library but i m not able to find the Soft PWM library code so please guide me how to use Soft Library for PWM Generation.

Thanks

 

[embpic]

you can use any one of timer from controller and to create freq on perticlar pin just toggle this pin.
but you will get 50% duty cycle.
to use variable duty cycle you have to program in software.
first make 1 this pin use nop's then 0 this pin in isr only.

 

[asking]

you can use any one of timer from controller and to create freq on perticlar pin just toggle this pin.
but you will get 50% duty cycle.
to use variable duty cycle you have to program in software.
first make 1 this pin use nop's then 0 this pin in isr only.

can you provide me some more details about Soft PWM ? using Timers and interrupts ?

Thanks

 

[tpetar]

MikroC - Software PWM & RGB LED PIC16F628
https://electronicexperiments.blogspot.com/2010/10/lesson-nr10-software-pwm-rgb-led.html

 

[asking]

void interrupt()
{
  if (INTCON.TMR0IF ==1) // timer 0 interrupt flag
  {
    GPIO = ~GPIO;      // Toggle PORTB bit0 LED
    INTCON.TMR0IF = 0;         // clear the flag
    INTCON.TMR0IE = 1;         // reenable the interrupt
    TMR0 = 204;           // reset the timer preset count
  }

}



// code starts here...
void main()
{

  // setup portb to show the interrupts by blibking LEDs
  TRISIO = 0;    // PORT is all output...to show the interrupts
  GPIO = 0;       // start with all outputs low
  ANSEL = 0;

//Timer0 Registers Prescaler= 1 - TMR0 Preset = 204 - Freq = 38461.54 Hz - Period = 0.000026 seconds
OPTION_REG.T0CS = 0;  // bit 5  TMR0 Clock Source Select bit...0 = Internal Clock (CLKO) 1 = Transition on T0CKI pin
OPTION_REG.T0SE = 0;  // bit 4 TMR0 Source Edge Select bit 0 = low/high 1 = high/low
OPTION_REG.PSA = 1;   // bit 3  Prescaler Assignment bit...0 = Prescaler is assigned to the WDT
OPTION_REG.PS2 = 0;   // bits 2-0  PS2:PS0: Prescaler Rate Select bits
OPTION_REG.PS1 = 0;
OPTION_REG.PS0 = 0;
TMR0 = 238;             // preset for timer register


// Interrupt Registers
  INTCON = 0;           // clear the interrpt control register
  INTCON.TMR0IE = 1;        // bit5 TMR0 Overflow Interrupt Enable bit...1 = Enables the TMR0 interrupt
  INTCON.TMR0IF = 0;        // bit2 clear timer 0 interrupt flag
  INTCON.GIE = 1;           // bit7 global interrupt enable


  while(1)  //endless loop
  {
  }
}

But i m getting 9.13KHZ Maximum Frequency on 12F675, i tested with DS0201 Oscilloscope.

Please do needful. I am Running 12F675 with internal Oscillator 4 MHZ. and i want 38KHZ to drive IR led for TSOP1838.