Ejemplo n.º 1
0
/**
 * Get the PWM value in terms of speed.
 * 
 * This is intended to be used by speed controllers.
 * 
 * @pre SetMaxPositivePwm() called.
 * @pre SetMinPositivePwm() called.
 * @pre SetMaxNegativePwm() called.
 * @pre SetMinNegativePwm() called.
 * 
 * @return The most recently set speed between -1.0 and 1.0.
 */
float PWM::GetSpeed()
{
	if (StatusIsFatal()) return 0.0;
	INT32 value = GetRaw();
	if (value > GetMaxPositivePwm())
	{
		return 1.0;
	}
	else if (value < GetMinNegativePwm())
	{
		return -1.0;
	}
	else if (value > GetMinPositivePwm())
	{
		return (float)(value - GetMinPositivePwm()) / (float)GetPositiveScaleFactor();
	}
	else if (value < GetMaxNegativePwm())
	{
		return (float)(value - GetMaxNegativePwm()) / (float)GetNegativeScaleFactor();
	}
	else
	{
		return 0.0;
	}
}
Ejemplo n.º 2
0
/**
 * Set the PWM value based on a speed.
 *
 * This is intended to be used by speed controllers.
 *
 * @pre SetMaxPositivePwm() called.
 * @pre SetMinPositivePwm() called.
 * @pre SetCenterPwm() called.
 * @pre SetMaxNegativePwm() called.
 * @pre SetMinNegativePwm() called.
 *
 * @param speed The speed to set the speed controller between -1.0 and 1.0.
 */
void PWM::SetSpeed(float speed) {
  if (StatusIsFatal()) return;
  // clamp speed to be in the range 1.0 >= speed >= -1.0
  if (speed < -1.0) {
    speed = -1.0;
  } else if (speed > 1.0) {
    speed = 1.0;
  }

  // calculate the desired output pwm value by scaling the speed appropriately
  int32_t rawValue;
  if (speed == 0.0) {
    rawValue = GetCenterPwm();
  } else if (speed > 0.0) {
    rawValue = (int32_t)(speed * ((float)GetPositiveScaleFactor()) +
                         ((float)GetMinPositivePwm()) + 0.5);
  } else {
    rawValue = (int32_t)(speed * ((float)GetNegativeScaleFactor()) +
                         ((float)GetMaxNegativePwm()) + 0.5);
  }

  // the above should result in a pwm_value in the valid range
  wpi_assert((rawValue >= GetMinNegativePwm()) &&
             (rawValue <= GetMaxPositivePwm()));
  wpi_assert(rawValue != kPwmDisabled);

  // send the computed pwm value to the FPGA
  SetRaw(rawValue);
}
Ejemplo n.º 3
0
/**
 * Get the PWM value in terms of speed.
 *
 * This is intended to be used by speed controllers.
 *
 * @pre SetMaxPositivePwm() called.
 * @pre SetMinPositivePwm() called.
 * @pre SetMaxNegativePwm() called.
 * @pre SetMinNegativePwm() called.
 *
 * @return The most recently set speed between -1.0 and 1.0.
 */
float PWM::GetSpeed() const {
  if (StatusIsFatal()) return 0.0;
  int32_t value = GetRaw();
  if (value == PWM::kPwmDisabled) {
    return 0.0;
  } else if (value > GetMaxPositivePwm()) {
    return 1.0;
  } else if (value < GetMinNegativePwm()) {
    return -1.0;
  } else if (value > GetMinPositivePwm()) {
    return (float)(value - GetMinPositivePwm()) /
           (float)GetPositiveScaleFactor();
  } else if (value < GetMaxNegativePwm()) {
    return (float)(value - GetMaxNegativePwm()) /
           (float)GetNegativeScaleFactor();
  } else {
    return 0.0;
  }
}