Function esp_idf_sys::adc2_vref_to_gpio

pub unsafe extern "C" fn adc2_vref_to_gpio(gpio: gpio_num_t) -> esp_err_t

@brief Output ADC2 reference voltage to gpio 25 or 26 or 27

This function utilizes the testing mux exclusive to ADC 2 to route the reference voltage one of ADC2's channels. Supported gpios are gpios 25, 26, and 27. This refernce voltage can be manually read from the pin and used in the esp_adc_cal component.

@param[in] gpio GPIO number (gpios 25,26,27 supported)

@return - ESP_OK: v_ref successfully routed to selected gpio - ESP_ERR_INVALID_ARG: Unsupported gpio