/*----------------------------------------------------------------------------*
* NAME
* dutyCycleTask
*
* DESCRIPTION
* This is the function called when the timer expires.
*
* Creates a timer for updating the duty cycle on the PWM1. The ramping
* effect is produced on the PWM1 by updating its duty cycle periodically
* while maintaining constant frequency.
*
* The PWM1 is configured for its duty cycle from this timer call-back. The
* duty cycle is updated from 0% to 100% and then down to 0% and so on.
*
* PARAMETERS
* tid Id of the timer that has just expired. It is not used.
*
* RETURNS/MODIFIES
* None
*----------------------------------------------------------------------------*/
static void dutyCycleTask( timer_id const tid )
{
static uint8 on_ticks = 0U;
static int8 increment_value = 1U; /* Hold the value by which ON time is
incremented. When duty cycle is
increasing it holds possitive value.
When duty cycle is decreasing it
holds negative value */
/* Configure the PWM1 to produce a fixed frequency signal, with the same
* duty cycle for both the dullest and brightest parts. */
setPwmDutyCycle(on_ticks);
if ( on_ticks >= NUMBER_OF_STEPS )
/* When ON time reaches its maximum (i.e. 100% duty cycle)
* it should be decremented until it reaches minimum (i.e. 0%) */
{
increment_value = -1;
}
else if ( on_ticks <= 0U )
/* When ON time reaches its minimum (i.e. 0% duty cycle)
* it should be incremented until it reaches maximum (i.e. 100%) */
{
increment_value = 1;
}
/* Update ON time for the next update */
on_ticks += increment_value;
/* Re-start the timer */
TimerCreate(DUTY_CYCLE_STEP_TIME, TRUE, dutyCycleTask);
}
void analogWrite(uint8_t pin, int16_t val)
{
uint8_t timer = 0xff;
setPinMode(pin, OUTPUT);
if ((val == 0) || (val <0))
{
digitalWrite(pin, LOW);
}
else if ((val > 255) || (val == 255))
{
digitalWrite(pin, HIGH);
}
else
{
timer = digitalPinToTimer(pin);
initPwm(timer);
setPwmDutyCycle((uint8_t)val, timer);
}
}
