Function esp_idf_sys::touch_pad_set_voltage

pub unsafe extern "C" fn touch_pad_set_voltage(
    refh: touch_high_volt_t, 
    refl: touch_low_volt_t, 
    atten: touch_volt_atten_t
) -> esp_err_t

@brief Set touch sensor reference voltage, if the voltage gap between high and low reference voltage get less, the charging and discharging time would be faster, accordingly, the counter value would be larger. In the case of detecting very slight change of capacitance, we can narrow down the gap so as to increase the sensitivity. On the other hand, narrow voltage gap would also introduce more noise, but we can use a software filter to pre-process the counter value. @param refh the value of DREFH @param refl the value of DREFL @param atten the attenuation on DREFH @return - ESP_OK on success - ESP_ERR_INVALID_ARG if argument is wrong