Timer0_PWM.c File Reference

#include "config.h"
#include "Timer0_PWM.h"

Include dependency graph for Timer0_PWM.c:

Go to the source code of this file.

Functions
void	Timer0_start (void)
	Timer0_start configures timer 0 for PWM on Output compare 0 B Configures timer as following: Count clock is Fosc/1 (prescaler -> clk/1), 8Mhz Fast PWM mode use Uses output compare pin OCR0B OC0B is set from 0 to OCR0B, then cleared up to timer0 TOP Waveform generator configured : Timer 0 top is 0xFF (8 bit count) Starts with a 0% PWM ratio.
void	manage_time_base (void)
	manage_time_base Should be executed in background to generate a non critical time base. Time base counter should be decremented each 32µs on Timer0 overflow. When Time base counter reaches 0, one second has elapsed. A flag is set and counter is set again to its init value.
Variables
SoftTimer_t	time_count_1s
	variable used to decrement to zero each elapsed second

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Function Documentation

void Timer0_start

(

void

)

Timer0_start configures timer 0 for PWM on Output compare 0 B Configures timer as following:

• Count clock is Fosc/1 (prescaler -> clk/1), 8Mhz
• Fast PWM mode use
• Uses output compare pin OCR0B
• OC0B is set from 0 to OCR0B, then cleared up to timer0 TOP
• Waveform generator configured : Timer 0 top is 0xFF (8 bit count)
• Starts with a 0% PWM ratio.

Definition at line 52 of file Timer0_PWM.c.

References TIMER0_SET_OC0B_PWM.

Referenced by main().

{
  // clear output compare pin at OCR0B compare match, set at TOP (0xFF) 
  TCCR0A = (1<<COM0B1) | (1<<WGM01) | (1<<WGM00);   
  // Set Fast PWM mode with output compare : Wave form generation Fast PWM, 
  // top counter value 0xFF, clk/1 prescaler -> Overflow (PWM) period = 32µs
  TCCR0B = (1<<CS00);
  // PWM ratio set to zero
  TIMER0_SET_OC0B_PWM (0x00);
}

void manage_time_base

(

void

)

manage_time_base Should be executed in background to generate a non critical time base. Time base counter should be decremented each 32µs on Timer0 overflow. When Time base counter reaches 0, one second has elapsed. A flag is set and counter is set again to its init value.

Definition at line 71 of file Timer0_PWM.c.

References SoftTimer_t::count, ONE_SECOND, SoftTimer_t::ovf, and time_count_1s.

Referenced by main().

{
  if (TIFR0 & (1<<TOV0))          // Has Timer 0 overflowed ?
  {
    if (time_count_1s.count > 0)
      time_count_1s.count--;
    else
    {
      time_count_1s.count = ONE_SECOND;  // 31250 * 32µs --> 1s period counter
      time_count_1s.ovf = true;
    }
    TIFR0 |= (1<<TOV0);           // Clear Timer 0 overflow flag bit
  }
}

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Variable Documentation

SoftTimer_t time_count_1s

variable used to decrement to zero each elapsed second

Definition at line 41 of file Timer0_PWM.c.

Referenced by display_defaults(), manage_time_base(), and refresh_ATA6824_watchdog().

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