Function sdm_channel_set_duty 

pub unsafe extern "C" fn sdm_channel_set_duty(
    chan: *mut sdm_channel_t,
    duty: i8,
) -> i32

@brief The alias function of sdm_channel_set_pulse_density, it decides the pulse density of the output signal

@note sdm_channel_set_pulse_density has a more appropriate name compare this alias function, suggest to turn to sdm_channel_set_pulse_density instead

@param[in] chan SDM channel created by sdm_new_channel @param[in] duty Actually it’s the quantized pulse density of the PDM output signal

@return - ESP_OK: Set duty cycle successfully - ESP_ERR_INVALID_ARG: Set duty cycle failed because of invalid argument - ESP_FAIL: Set duty cycle failed because of other error