adc: add curve fitting converter

components/ocs_io/CMakeLists.txt

@@ -12,6 +12,8 @@ set(COMPONENT_SRCS
 
 if(IDF_TARGET STREQUAL "esp32")
     list(APPEND COMPONENT_SRCS "adc/target_esp32/line_fitting_converter.cpp")
+elseif(IDF_TARGET STREQUAL "esp32s3")
+    list(APPEND COMPONENT_SRCS "adc/target_esp32/curve_fitting_converter.cpp")
 endif()
 
 idf_component_register(

components/ocs_io/adc/target_esp32/curve_fitting_converter.cpp

@@ -0,0 +1,32 @@
+/*
+ * SPDX-FileCopyrightText: 2026 Tendry Lab
+ * SPDX-License-Identifier: Apache-2.0
+ */
+
+#include <cstring>
+
+#include "ocs_io/adc/target_esp32/curve_fitting_converter.h"
+
+namespace ocs {
+namespace io {
+namespace adc {
+
+CurveFittingConverter::CurveFittingConverter(adc_unit_t unit,
+                                             adc_atten_t atten,
+                                             adc_bitwidth_t bitwidth) {
+    memset(&calibration_config_, 0, sizeof(calibration_config_));
+    calibration_config_.unit_id = unit;
+    calibration_config_.atten = atten;
+    calibration_config_.bitwidth = bitwidth;
+
+    ESP_ERROR_CHECK(
+        adc_cali_create_scheme_curve_fitting(&calibration_config_, &calibration_handle_));
+}
+
+CurveFittingConverter::~CurveFittingConverter() {
+    ESP_ERROR_CHECK(adc_cali_delete_scheme_curve_fitting(calibration_handle_));
+}
+
+} // namespace adc
+} // namespace io
+} // namespace ocs

components/ocs_io/adc/target_esp32/curve_fitting_converter.h

@@ -0,0 +1,34 @@
+/*
+ * SPDX-FileCopyrightText: 2026 Tendry Lab
+ * SPDX-License-Identifier: Apache-2.0
+ */
+
+#pragma once
+
+#include "esp_adc/adc_cali_scheme.h"
+
+#include "ocs_core/noncopyable.h"
+#include "ocs_io/adc/target_esp32/basic_converter.h"
+
+namespace ocs {
+namespace io {
+namespace adc {
+
+//! Convert ADC raw data to calibrated voltage.
+//!
+//! https://docs.espressif.com/projects/esp-idf/en/stable/esp32/api-reference/peripherals/adc_calibration.html
+class CurveFittingConverter : public BasicConverter, private core::NonCopyable<> {
+public:
+    //! Initialize.
+    CurveFittingConverter(adc_unit_t unit, adc_atten_t atten, adc_bitwidth_t bitwidth);
+
+    //! Destroy.
+    ~CurveFittingConverter();
+
+private:
+    adc_cali_curve_fitting_config_t calibration_config_;
+};
+
+} // namespace adc
+} // namespace io
+} // namespace ocs