upm_result_t speaker_set_frequency(const speaker_context dev,
unsigned int freq)
{
assert(dev != NULL);
if (!dev->is_pwm)
return UPM_ERROR_NO_RESOURCES;
if (freq < 50 || freq > 32000)
{
printf("%s: freq must be between 50 and 32000.\n", __FUNCTION__);
return UPM_ERROR_OPERATION_FAILED;
}
float period = 1.0 / (float)freq;
// printf("PERIOD: %f (freq %d)\n", period, freq);
if (period >= 0.001) // ms range
{
if (mraa_pwm_period(dev->pwm, period))
{
printf("%s: mraa_pwm_period() failed.\n", __FUNCTION__);
return UPM_ERROR_OPERATION_FAILED;
}
}
else // us range. With a max of 32KHz, no less than 3.125 us.
{
if (mraa_pwm_period_us(dev->pwm, (int)(period * 1000000)))
{
printf("%s: mraa_pwm_period_us() failed.\n", __FUNCTION__);
return UPM_ERROR_OPERATION_FAILED;
}
}
// save it for later if needed
dev->default_freq = freq;
// A 10% duty cycle enables better results at high frequencies
mraa_pwm_write(dev->pwm, 0.1);
return UPM_SUCCESS;
}
/**
* Set the PWM period as seconds represented in a float
*
* @param period Period represented as a float in seconds
* @return Result of operation
*/
mraa_result_t
period(float period)
{
return mraa_pwm_period(m_pwm, period);
}