Merge branch 'feature/add_adc_interface' into 'master'

feature(adc): add adc interface

See merge request sdk/ESP8266_RTOS_SDK!681

components/esp8266/driver/adc.c

@@ -0,0 +1,55 @@
+// Copyright 2018-2025 Espressif Systems (Shanghai) PTE LTD
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+
+#include <stdio.h>
+#include <stdint.h>
+
+#include "esp_attr.h"
+#include "esp_err.h"
+#include "esp_log.h"
+
+#include "driver/adc.h"
+
+#define ENTER_CRITICAL() portENTER_CRITICAL()
+#define EXIT_CRITICAL() portEXIT_CRITICAL()
+
+static const char *TAG = "adc";
+
+#define ADC_CHECK(a, str, ret_val) \
+    if (!(a)) { \
+        ESP_LOGE(TAG,"%s(%d): %s", __FUNCTION__, __LINE__, str); \
+        return (ret_val); \
+    }
+
+extern uint16_t test_tout();
+extern void phy_adc_read_fast(uint16_t *adc_addr, uint16_t adc_num, uint8_t adc_clk_div);
+extern uint16_t phy_get_vdd33();
+
+uint16_t adc_read()
+{
+    uint16_t ret = test_tout(0);
+
+    if (ret != 0xFFFF) {
+        // The working voltage of ADC is designed according to 1.1v. Later, the actual working voltage of ADC is increased to 1.2v, so this scale is added.
+        ret = ret * 12 / 11;
+
+        if (ret > 1023) {
+            // 10-bit precision ADC
+            ret = 1023;
+        }
+    }
+
+    return ret;
+}