Delete some of the sdkconfig that I think are not needed anymore also made basic measurements working

- Still todo is the real calibration and testing
- The continous logging to the server works

main/station_example_main.c

@@ -1,12 +1,9 @@
-/* WiFi station Example
+/*
+ Voltage measurement device over wifi from WiFi station Example
+  */
 
-   This example code is in the Public Domain (or CC0 licensed, at your option.)
-
-   Unless required by applicable law or agreed to in writing, this
-   software is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR
-   CONDITIONS OF ANY KIND, either express or implied.
-*/
 #include <string.h>
+
 #include "freertos/FreeRTOS.h"
 #include "freertos/task.h"
 #include "freertos/event_groups.h"
@@ -22,9 +19,19 @@
 
 #include "esp_adc/adc_continuous.h"
 #include "esp_adc/adc_cali.h"
+#include "esp_adc/adc_oneshot.h"
+#include "esp_adc/adc_cali.h"
+#include "esp_adc/adc_cali_scheme.h"
 #include "esp_http_client.h"
 
+/* ===================== CONSTS ===================== */
+
 #define SERVER_URL "http://192.168.178.157:8080/data"
+#define RMS_WINDOW_MS 300
+#define CHANNEL ADC_CHANNEL_6
+
+// TODO: Determine this
+#define CALIBRATION_FACTOR 1650.0f
 
 /* The examples use WiFi configuration that you can set via project configuration menu
 
@@ -63,6 +70,11 @@
 #define ESP_WIFI_SCAN_AUTH_MODE_THRESHOLD WIFI_AUTH_WAPI_PSK
 #endif
 
+// Tag for logging
+static const char *TAG = "VoltageSensor";
+
+/* ===================== WIFI ===================== */
+
 /* FreeRTOS event group to signal when we are connected*/
 static EventGroupHandle_t s_wifi_event_group;
 
@@ -72,11 +84,9 @@ static EventGroupHandle_t s_wifi_event_group;
 #define WIFI_CONNECTED_BIT BIT0
 #define WIFI_FAIL_BIT      BIT1
 
-static const char *TAG = "wifi station";
-
 static int s_retry_num = 0;
 
-
+// Internal wifi event_handler
 static void event_handler(void* arg, esp_event_base_t event_base,
                                 int32_t event_id, void* event_data)
 {
@@ -99,6 +109,7 @@ static void event_handler(void* arg, esp_event_base_t event_base,
     }
 }
 
+// Initialize the wifi
 void wifi_init_sta(void)
 {
     s_wifi_event_group = xEventGroupCreate();
@@ -165,31 +176,95 @@ void wifi_init_sta(void)
     }
 }
 
-void send_voltage(float v)
+// Function to send the voltage to a remote server
+void send_voltage(esp_http_client_handle_t client, float v)
 {
+    // Simple payload for the go server
     char payload[64];
-    snprintf(payload, sizeof(payload),
-             "{\"voltage\":%.2f}", v);
+    snprintf(payload, sizeof(payload), "{\"voltage\":%.2f}", v);
 
+    esp_http_client_set_post_field(client, payload, strlen(payload));
+    esp_http_client_perform(client);
+}
+
+/* ===================== ADC ===================== */
+
+static adc_oneshot_unit_handle_t adc_handle;
+static adc_cali_handle_t cali_handle;
+static bool cali_enabled = false;
+
+static void adc_init(void)
+{
+    // Setup oneshot
+    adc_oneshot_unit_init_cfg_t unit_cfg = {
+        .unit_id = ADC_UNIT_1,
+        .ulp_mode = ADC_ULP_MODE_DISABLE,
+    };
+    ESP_ERROR_CHECK(adc_oneshot_new_unit(&unit_cfg, &adc_handle));
+
+    adc_oneshot_chan_cfg_t chan_cfg = {
+        .atten = ADC_ATTEN_DB_12,
+        .bitwidth = ADC_BITWIDTH_DEFAULT,
+    };
+    ESP_ERROR_CHECK(adc_oneshot_config_channel(adc_handle, CHANNEL, &chan_cfg));
+
+    // Calibration of the adc
+    adc_cali_scheme_ver_t scheme;
+    if (adc_cali_check_scheme(&scheme) != ESP_OK) {
+        ESP_LOGW(TAG, "ADC calibration not supported");
+        return;
+    }
+
+    if (scheme & ADC_CALI_SCHEME_VER_LINE_FITTING) {
+        adc_cali_line_fitting_config_t cfg = {
+            .unit_id = ADC_UNIT_1,
+            .atten = ADC_ATTEN_DB_12,
+            .bitwidth = ADC_BITWIDTH_DEFAULT,
+        };
+        ESP_ERROR_CHECK(adc_cali_create_scheme_line_fitting(&cfg, &cali_handle));
+        cali_enabled = true;
+    }
+}
+
+static float read_voltage_mv(void)
+{
+    int raw;
+    int mv = 0;
+
+    ESP_ERROR_CHECK(adc_oneshot_read(adc_handle, CHANNEL, &raw));
+    if (cali_enabled) {
+        ESP_ERROR_CHECK(adc_cali_raw_to_voltage(cali_handle, raw, &mv));
+    }
+
+    ESP_LOGI(TAG, "Raw measurement from sensor to calibrated value: %d -> %d", raw, mv);
+    return (mv - CALIBRATION_FACTOR) / CALIBRATION_FACTOR;
+}
+
+/* ===================== MAIN ===================== */
+
+static void measure_task(void *arg)
+{
+    // Setup client to be reused
     esp_http_client_config_t cfg = {
         .url = SERVER_URL,
         .method = HTTP_METHOD_POST,
         .timeout_ms = 2000,
     };
+    esp_http_client_handle_t client = esp_http_client_init(&cfg);
+    esp_http_client_set_header(client, "Content-Type", "application/json");
 
-    esp_http_client_handle_t client =
-        esp_http_client_init(&cfg);
+    // Main measure loop
+    while (1) {
+        float v = read_voltage_mv();
+        vTaskDelay(pdMS_TO_TICKS(50)); // Does this do anything?
+        send_voltage(client, v);
+        vTaskDelay(pdMS_TO_TICKS(RMS_WINDOW_MS));
+    }
 
-    esp_http_client_set_header(
-        client, "Content-Type", "application/json");
-    esp_http_client_set_post_field(
-        client, payload, strlen(payload));
-
-    esp_http_client_perform(client);
+    // Cleanup after task
     esp_http_client_cleanup(client);
 }
 
-
 void app_main(void)
 {
     //Initialize NVS
@@ -208,5 +283,8 @@ void app_main(void)
 
     ESP_LOGI(TAG, "ESP_WIFI_MODE_STA");
     wifi_init_sta();
-    send_voltage(0.5);
+    adc_init();
+
+    ESP_LOGI(TAG, "Start measure");
+    xTaskCreate(measure_task, "measure", 4096, NULL, 5, NULL);
 }