feat(esp32-IMU): Upload IMU program progress

MQTT - functions

TODO:
  - Fix Serial

IMU/.clangd

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+CompileFlags:
+    Remove: [-f*, -m*]

IMU/.devcontainer/Dockerfile

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+ARG DOCKER_TAG=latest
+FROM espressif/idf:${DOCKER_TAG}
+
+ENV LC_ALL=C.UTF-8
+ENV LANG=C.UTF-8
+
+RUN apt-get update -y && apt-get install udev -y
+
+RUN echo "source /opt/esp/idf/export.sh > /dev/null 2>&1" >> ~/.bashrc
+
+ENTRYPOINT [ "/opt/esp/entrypoint.sh" ]
+
+CMD ["/bin/bash", "-c"]

IMU/.devcontainer/devcontainer.json

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+{
+	"name": "ESP-IDF QEMU",
+	"build": {
+		"dockerfile": "Dockerfile"
+	},
+	"customizations": {
+		"vscode": {
+			"settings": {
+				"terminal.integrated.defaultProfile.linux": "bash",
+				"idf.espIdfPath": "/opt/esp/idf",
+				"idf.toolsPath": "/opt/esp",
+				"idf.gitPath": "/usr/bin/git"
+			},
+			"extensions": [
+				"espressif.esp-idf-extension",
+				"espressif.esp-idf-web"
+			]
+		}
+	},
+	"runArgs": ["--privileged"]
+}

IMU/.editorconfig

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+[*]
+cpp_indent_braces=false
+cpp_indent_multi_line_relative_to=innermost_parenthesis
+cpp_indent_within_parentheses=indent
+cpp_indent_preserve_within_parentheses=true
+cpp_indent_case_labels=true
+cpp_indent_case_contents=true
+cpp_indent_case_contents_when_block=false
+cpp_indent_lambda_braces_when_parameter=true
+cpp_indent_goto_labels=one_left
+cpp_indent_preprocessor=leftmost_column
+cpp_indent_access_specifiers=false
+cpp_indent_namespace_contents=false
+cpp_indent_preserve_comments=false
+
+cpp_new_line_before_open_brace_namespace=false
+cpp_new_line_before_open_brace_type=false
+cpp_new_line_before_open_brace_function=ignore
+cpp_new_line_before_open_brace_block=ignore
+cpp_new_line_before_open_brace_lambda=ignore
+
+cpp_new_line_scope_braces_on_separate_lines=false
+cpp_new_line_close_brace_same_line_empty_type=false
+cpp_new_line_close_brace_same_line_empty_function=false
+cpp_new_line_before_catch=false
+cpp_new_line_before_else=false
+cpp_new_line_before_while_in_do_while=false
+
+cpp_space_before_function_open_parenthesis=remove
+cpp_space_within_parameter_list_parentheses=false
+cpp_space_between_empty_parameter_list_parentheses=false
+cpp_space_after_keywords_in_control_flow_statements=true
+cpp_space_within_control_flow_statement_parentheses=false
+cpp_space_before_lambda_open_parenthesis=false
+
+cpp_space_within_cast_parentheses=false
+cpp_space_after_cast_close_parenthesis=false
+cpp_space_within_expression_parentheses=false
+cpp_space_before_block_open_brace=true
+cpp_space_between_empty_braces=false
+cpp_space_before_initializer_list_open_brace=true
+cpp_space_within_initializer_list_braces=true
+cpp_space_preserve_in_initializer_list=true
+
+cpp_space_before_open_square_bracket=false
+cpp_space_within_square_brackets=false
+cpp_space_before_empty_square_brackets=false
+cpp_space_between_empty_square_brackets=false
+cpp_space_group_square_brackets=true
+
+cpp_space_within_lambda_brackets=false
+cpp_space_between_empty_lambda_brackets=false
+cpp_space_before_comma=false
+cpp_space_after_comma=true
+
+cpp_space_remove_around_member_operators=true
+
+cpp_space_before_inheritance_colon=true
+cpp_space_before_constructor_colon=true
+
+cpp_space_remove_before_semicolon=true
+cpp_space_after_semicolon=true
+
+cpp_space_remove_around_unary_operator=true
+
+cpp_space_around_binary_operator=insert
+cpp_space_around_assignment_operator=insert
+cpp_space_pointer_reference_alignment=left
+cpp_space_around_ternary_operator=insert
+cpp_wrap_preserve_blocks=one_liners
+indent_style = space
+indent_size = 4
+charset = utf-8
+trim_trailing_whitespace = true
+insert_final_newline = true

IMU/CMakeLists.txt

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+# The following lines of boilerplate have to be in your project's CMakeLists
+# in this exact order for cmake to work correctly
+cmake_minimum_required(VERSION 3.16)
+
+include($ENV{IDF_PATH}/tools/cmake/project.cmake)
+project(IMU)

IMU/main/CMakeLists.txt

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+idf_component_register(SRCS "mpu6886.c"
+                       INCLUDE_DIRS ".")

IMU/main/Kconfig.projbuild

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+menu "Example Configuration"
+
+    orsource "$IDF_PATH/examples/common_components/env_caps/$IDF_TARGET/Kconfig.env_caps"
+
+    config I2C_MASTER_SCL
+        int "SCL GPIO Num"
+        range ENV_GPIO_RANGE_MIN ENV_GPIO_OUT_RANGE_MAX
+        default 4
+        help
+            GPIO number for I2C Master clock line.
+
+    config I2C_MASTER_SDA
+        int "SDA GPIO Num"
+        range ENV_GPIO_RANGE_MIN ENV_GPIO_OUT_RANGE_MAX
+        default 5
+        help
+            GPIO number for I2C Master data line.
+
+    config I2C_MASTER_FREQUENCY
+        int "Master Frequency"
+        default 400000
+        help
+            I2C Speed of Master device.
+
+    config WIFI_SSID
+        string "WiFi SSID"
+        default "YourNetworkName"
+        help
+            SSID of WiFi network to connect to.
+
+    config WIFI_PASSWORD
+        string "WiFi Password"
+        default "YourPassword"
+        help
+            Password of WiFi network to connect to.
+
+    config MQTT_BROKER_URI
+        string "MQTT Broker URI"
+        default "mqtt://192.168.178.26:1883"
+        help
+            URI of the MQTT broker to connect to.
+
+    config MQTT_TOPIC
+        string "MQTT Topic"
+        default "esp32/imu"
+        help
+            MQTT topic to publish IMU data to.
+
+    config WIFI_AP_MODE
+        bool "Enable WiFi AP Mode"
+        default n
+        help
+            Enable this option to start the device in Access Point mode.
+            If disabled, the device will start in Station mode.
+
+    config WIFI_AP_SSID
+        string "WiFi AP SSID"
+        default "ESP32_IMU_AP"
+        help
+            SSID of the WiFi Access Point when in AP mode.
+
+    config WIFI_AP_PASSWORD
+        string "WiFi AP Password"
+        default "esp32imuap"
+        help
+            Password of the WiFi Access Point when in AP mode.
+endmenu

IMU/main/mpu6886.c

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+#include "mpu6886.h"
+#include <string.h>
+
+
+// New: initialise WiFi in either STA or AP mode. Pass ap_mode=true to start an Access Point.
+static void wifi_init(bool ap_mode)
+{
+    ESP_ERROR_CHECK(nvs_flash_init());
+    ESP_ERROR_CHECK(esp_netif_init());
+    ESP_ERROR_CHECK(esp_event_loop_create_default());
+
+    wifi_init_config_t cfg = WIFI_INIT_CONFIG_DEFAULT();
+    ESP_ERROR_CHECK(esp_wifi_init(&cfg));
+
+    if (ap_mode) {
+        esp_netif_create_default_wifi_ap();
+
+        wifi_config_t wifi_config = { 0 };
+        strncpy((char *)wifi_config.ap.ssid, CONFIG_WIFI_AP_SSID, sizeof(wifi_config.ap.ssid));
+        wifi_config.ap.ssid_len = strlen(CONFIG_WIFI_AP_SSID);
+        strncpy((char *)wifi_config.ap.password, CONFIG_WIFI_AP_PASSWORD, sizeof(wifi_config.ap.password));
+        wifi_config.ap.max_connection = 4;
+        if (strlen(CONFIG_WIFI_AP_PASSWORD) == 0) {
+            wifi_config.ap.authmode = WIFI_AUTH_OPEN;
+        } else {
+            wifi_config.ap.authmode = WIFI_AUTH_WPA_WPA2_PSK;
+        }
+
+        ESP_ERROR_CHECK(esp_wifi_set_mode(WIFI_MODE_AP));
+        ESP_ERROR_CHECK(esp_wifi_set_config(WIFI_IF_AP, &wifi_config));
+        ESP_ERROR_CHECK(esp_wifi_start());
+        ESP_LOGI("WIFI", "AP started SSID:%s", CONFIG_WIFI_AP_SSID);
+    } else {
+        esp_netif_create_default_wifi_sta();
+
+        wifi_config_t wifi_config = {
+            .sta = {
+                .ssid = CONFIG_WIFI_SSID,
+                .password = CONFIG_WIFI_PASSWORD,
+            },
+        };
+
+        ESP_ERROR_CHECK(esp_wifi_set_mode(WIFI_MODE_STA));
+        ESP_ERROR_CHECK(esp_wifi_set_config(WIFI_IF_STA, &wifi_config));
+        ESP_ERROR_CHECK(esp_wifi_start());
+        ESP_ERROR_CHECK(esp_wifi_connect());
+        ESP_LOGI("WIFI", "STA started, connecting to: %s", CONFIG_WIFI_SSID);
+    }
+}
+
+
+static esp_err_t mpu6886_write_byte(mpu6886_t *dev, uint8_t reg, uint8_t data) {
+    uint8_t tx[2] = { reg, data };
+    return i2c_master_write_to_device(dev->i2c_port, dev->address, tx, sizeof(tx), pdMS_TO_TICKS(100));
+}
+
+static esp_err_t mpu6886_read_bytes(mpu6886_t *dev, uint8_t reg, uint8_t *data, size_t len) {
+    return i2c_master_write_read_device(dev->i2c_port, dev->address, &reg, 1, data, len, pdMS_TO_TICKS(100));
+}
+
+static int16_t bytes_to_int16(uint8_t high, uint8_t low) {
+    return (int16_t)((high << 8) | low);
+}
+
+// Event handler uses esp_event handler signature; it receives mqtt event via event_data
+static void mqtt_event_handler_cb(void *handler_args, esp_event_base_t base, int32_t event_id, void *event_data)
+{
+    esp_mqtt_event_handle_t event = event_data;
+    switch (event->event_id) {
+    case MQTT_EVENT_CONNECTED:
+        ESP_LOGI("MQTT", "connected");
+        break;
+    case MQTT_EVENT_DISCONNECTED:
+        ESP_LOGW("MQTT", "disconnected");
+        break;
+    case MQTT_EVENT_ERROR:
+        ESP_LOGE("MQTT", "error");
+        break;
+    default:
+        break;
+    }
+}
+
+static void mqtt_app_start(void)
+{
+    esp_mqtt_client_config_t mqtt_cfg = { 0 };
+
+    mqtt_cfg.broker.address.uri = CONFIG_MQTT_BROKER_URI;
+
+    s_mqtt_client = esp_mqtt_client_init(&mqtt_cfg);
+    if (s_mqtt_client == NULL) {
+        ESP_LOGW("MQTT", "failed to init mqtt client");
+        return;
+    }
+    esp_mqtt_client_start(s_mqtt_client);
+}
+
+// new: detect accel/gyro full-scale selections and set divisors accordingly
+static esp_err_t mpu6886_update_sensitivity(mpu6886_t *dev)
+{
+    uint8_t aconf = 0, gconf = 0;
+    esp_err_t err;
+
+    err = mpu6886_read_bytes(dev, MPU6886_ACCEL_CONFIG, &aconf, 1);
+    if (err != ESP_OK) return err;
+    err = mpu6886_read_bytes(dev, MPU6886_GYRO_CONFIG, &gconf, 1);
+    if (err != ESP_OK) return err;
+
+    uint8_t a_fs = (aconf >> 3) & 0x03; // AFS_SEL bits [4:3]
+    switch (a_fs) {
+        case 0: dev->accel_div = ACCEL_SO_2G; break;   // ±2g
+        case 1: dev->accel_div = ACCEL_SO_4G; break;   // ±4g
+        case 2: dev->accel_div = ACCEL_SO_8G; break;   // ±8g
+        case 3: dev->accel_div = ACCEL_SO_16G; break;  // ±16g
+        default: dev->accel_div = ACCEL_SO_2G; break;
+    }
+
+    uint8_t g_fs = (gconf >> 3) & 0x03; // FS_SEL bits [4:3]
+    switch (g_fs) {
+        case 0: dev->gyro_div = GYRO_SO_250DPS; break;   // ±250 dps
+        case 1: dev->gyro_div = GYRO_SO_500DPS; break;   // ±500 dps
+        case 2: dev->gyro_div = GYRO_SO_1000DPS; break;  // ±1000 dps
+        case 3: dev->gyro_div = GYRO_SO_2000DPS; break;  // ±2000 dps
+        default: dev->gyro_div = GYRO_SO_250DPS; break;
+    }
+
+    return ESP_OK;
+}
+
+static esp_err_t i2c_master_init(i2c_port_t i2c_num, gpio_num_t sda_io, gpio_num_t scl_io, uint32_t clk_speed_hz)
+{
+    i2c_config_t conf = {
+        .mode = I2C_MODE_MASTER,
+        .sda_io_num = sda_io,
+        .sda_pullup_en = GPIO_PULLUP_ENABLE,
+        .scl_io_num = scl_io,
+        .scl_pullup_en = GPIO_PULLUP_ENABLE,
+        .master.clk_speed = clk_speed_hz,
+    };
+    esp_err_t err = i2c_param_config(i2c_num, &conf);
+    if (err != ESP_OK) return err;
+    return i2c_driver_install(i2c_num, I2C_MODE_MASTER, 0, 0, 0);
+}
+
+esp_err_t mpu6886_init(mpu6886_t *dev, i2c_port_t i2c_port) {
+    dev->i2c_port = i2c_port;
+    dev->address = MPU6886_ADDR;
+
+    uint8_t who_am_i = 0;
+    if (mpu6886_read_bytes(dev, MPU6886_WHO_AM_I, &who_am_i, 1) != ESP_OK) {
+        return ESP_FAIL;
+    }
+    if (who_am_i != 0x19) {
+        return ESP_FAIL;
+    }
+
+    // Reset
+    if (mpu6886_write_byte(dev, MPU6886_PWR_MGMT_1, 0x80) != ESP_OK) return ESP_FAIL;
+    vTaskDelay(pdMS_TO_TICKS(100));
+
+    // Auto select clock
+    if (mpu6886_write_byte(dev, MPU6886_PWR_MGMT_1, 0x01) != ESP_OK) return ESP_FAIL;
+
+    // Default config: set to ±2G accel, ±250DPS gyro (device may have different settings; we'll detect them)
+    mpu6886_write_byte(dev, MPU6886_ACCEL_CONFIG, 0x00);
+    mpu6886_write_byte(dev, MPU6886_GYRO_CONFIG, 0x00);
+
+    dev->gyro_offset = (vec3_t){0, 0, 0};
+    dev->accel_offset = (vec3_t){0, 0, 0};
+
+    // detect actual sensitivities from device registers and set divisors
+    if (mpu6886_update_sensitivity(dev) != ESP_OK) {
+        // fallback to defaults if read fails
+        dev->accel_div = ACCEL_SO_2G;
+        dev->gyro_div = GYRO_SO_250DPS;
+    }
+
+    return ESP_OK;
+}
+
+esp_err_t mpu6886_read_accel(mpu6886_t *dev, vec3_t *accel) {
+    uint8_t buf[6];
+    esp_err_t ret = mpu6886_read_bytes(dev, MPU6886_ACCEL_XOUT_H, buf, 6);
+    if (ret != ESP_OK) return ret;
+
+    // convert raw -> m/s^2 and apply stored offsets
+    accel->x = (float)bytes_to_int16(buf[0], buf[1]) / dev->accel_div * SF_M_S2 - dev->accel_offset.x;
+    accel->y = (float)bytes_to_int16(buf[2], buf[3]) / dev->accel_div * SF_M_S2 - dev->accel_offset.y;
+    accel->z = (float)bytes_to_int16(buf[4], buf[5]) / dev->accel_div * SF_M_S2 - dev->accel_offset.z;
+    return ESP_OK;
+}
+
+esp_err_t mpu6886_read_gyro(mpu6886_t *dev, vec3_t *gyro) {
+    uint8_t buf[6];
+    esp_err_t ret = mpu6886_read_bytes(dev, MPU6886_GYRO_XOUT_H, buf, 6);
+    if (ret != ESP_OK) return ret;
+
+    gyro->x = (float)bytes_to_int16(buf[0], buf[1]) / dev->gyro_div * SF_RAD_S - dev->gyro_offset.x;
+    gyro->y = (float)bytes_to_int16(buf[2], buf[3]) / dev->gyro_div * SF_RAD_S - dev->gyro_offset.y;
+    gyro->z = (float)bytes_to_int16(buf[4], buf[5]) / dev->gyro_div * SF_RAD_S - dev->gyro_offset.z;
+    return ESP_OK;
+}
+
+esp_err_t mpu6886_read_temp(mpu6886_t *dev, float *temp) {
+    static uint8_t buf[2];
+    esp_err_t ret = mpu6886_read_bytes(dev, MPU6886_TEMP_OUT_H, buf, 2);
+    if (ret != ESP_OK) return ret;
+
+    int16_t raw = bytes_to_int16(buf[0], buf[1]);
+    *temp = ((float)raw / TEMP_SO) + TEMP_OFFSET;
+    return ESP_OK;
+}
+
+esp_err_t mpu6886_calibrate_gyro(mpu6886_t *dev, int samples, int delay_ms) {
+    vec3_t sum = {0, 0, 0}, g;
+    for (int i = 0; i < samples; i++) {
+        if (mpu6886_read_gyro(dev, &g) != ESP_OK) return ESP_FAIL;
+        sum.x += g.x;
+        sum.y += g.y;
+        sum.z += g.z;
+        vTaskDelay(pdMS_TO_TICKS(delay_ms));
+    }
+    dev->gyro_offset.x = sum.x / samples;
+    dev->gyro_offset.y = sum.y / samples;
+    dev->gyro_offset.z = sum.z / samples;
+    return ESP_OK;
+}
+
+esp_err_t mpu6886_calibrate_accel(mpu6886_t *dev, int samples, int delay_ms)
+{
+    // Calibrate accelerometer offsets while the device is stationary.
+    // The function will detect the device full-scale and compute offsets in m/s^2.
+    vec3_t sum = {0, 0, 0}, a;
+    for (int i = 0; i < samples; i++) {
+        if (mpu6886_read_accel(dev, &a) != ESP_OK) {
+            return ESP_FAIL;
+        }
+        sum.x += a.x;
+        sum.y += a.y;
+        sum.z += a.z;
+        vTaskDelay(pdMS_TO_TICKS(delay_ms));
+    }
+    vec3_t avg = { sum.x / samples, sum.y / samples, sum.z / samples };
+
+    // For X/Y expect ~0 m/s^2 when stationary; offset = measured average
+    dev->accel_offset.x = avg.x;
+    dev->accel_offset.y = avg.y;
+
+    // For Z expect ~+1g (SF_M_S2) if +Z points up. If device is flipped you'll get -1g.
+    // Compute expected gravity sign from measured avg.z magnitude and sign.
+    float expected_g = (avg.z < 0) ? -SF_M_S2 : SF_M_S2;
+    dev->accel_offset.z = avg.z - expected_g;
+
+    return ESP_OK;
+}
+
+void app_main(void)
+{
+    esp_err_t err = i2c_master_init(I2C_NUM_0, CONFIG_I2C_MASTER_SDA, CONFIG_I2C_MASTER_SCL, CONFIG_I2C_MASTER_FREQUENCY); // adjust pins if needed
+    if (err != ESP_OK) {
+        ESP_LOGE("MPU6886", "I2C init failed: %d", err);
+        return;
+    }
+
+
+    // Start WiFi: set CONFIG_WIFI_AP_MODE in sdkconfig to build in AP mode,
+    // otherwise the default is STA mode. You can also call wifi_init(true)
+    // or wifi_init(false) directly to toggle at runtime.
+#ifdef CONFIG_WIFI_AP_MODE
+    wifi_init(true);
+#else
+    wifi_init(false);
+#endif
+
+    mpu6886_t mpu;
+    mpu.i2c_port = I2C_NUM_0;
+    mpu.address = MPU6886_ADDR;
+
+    esp_err_t ret = mpu6886_init(&mpu, I2C_NUM_0);
+    if (ret != ESP_OK) {
+        // Handle initialization error
+        ESP_LOGE("MPU6886", "init failed");
+        return;
+    }
+
+    // Start MQTT client (will retry until network is available)
+    mqtt_app_start();
+
+    mpu6886_calibrate_gyro(&mpu, 100, 10);
+    mpu6886_calibrate_accel(&mpu, 100, 10);
+    vec3_t accel, gyro;
+    float temp;
+
+    while (1) {
+        mpu6886_read_accel(&mpu, &accel);
+        mpu6886_read_gyro(&mpu, &gyro);
+        mpu6886_read_temp(&mpu, &temp);
+        ESP_LOGI("MPU6886", "Accel: X=%8.2f Y=%8.2f Z=%8.2f m/s² | Gyro: X=%8.2f Y=%8.2f Z=%8.2f rad/s | Temp: %8.2f °C",
+             accel.x, accel.y, accel.z, gyro.x, gyro.y, gyro.z, temp);
+
+        // Publish readings as JSON over MQTT if client available
+        if (s_mqtt_client != NULL) {
+            char payload[256];
+            int n = snprintf(payload, sizeof(payload),
+                "{\"accel\":{\"x\":%.3f,\"y\":%.3f,\"z\":%.3f},\"gyro\":{\"x\":%.3f,\"y\":%.3f,\"z\":%.3f},\"temp\":%.2f}",
+                accel.x, accel.y, accel.z,
+                gyro.x, gyro.y, gyro.z,
+                temp);
+            if (n > 0 && n < (int)sizeof(payload)) {
+                int msg_id = esp_mqtt_client_publish(s_mqtt_client, CONFIG_MQTT_TOPIC, payload, 0, 1, 0);
+                ESP_LOGD("MQTT", "published msg_id=%d payload_len=%d", msg_id, n);
+            } else {
+                ESP_LOGW("MQTT", "payload truncated or encoding error");
+            }
+        }
+        vTaskDelay(pdMS_TO_TICKS(100));
+    }
+}

IMU/main/mpu6886.h

@@ -0,0 +1,80 @@
+#ifndef MPU6886_H
+#define MPU6886_H
+
+#include "driver/i2c.h"
+#include "esp_err.h"
+#include "esp_wifi.h"
+#include "esp_event.h"
+#include "esp_log.h"
+#include "nvs_flash.h"
+#include "freertos/FreeRTOS.h"
+#include "freertos/task.h"
+#include <math.h>
+#include "mqtt_client.h"
+#include <string.h>
+#include <stdio.h>
+
+
+#define I2C_MASTER_SCL_IO           CONFIG_I2C_MASTER_SCL       /*!< GPIO number used for I2C master clock */
+#define I2C_MASTER_SDA_IO           CONFIG_I2C_MASTER_SDA       /*!< GPIO number used for I2C master data  */
+#define I2C_MASTER_NUM              I2C_NUM_0                   /*!< I2C port number for master dev */
+#define I2C_MASTER_FREQ_HZ          CONFIG_I2C_MASTER_FREQUENCY /*!< I2C master clock frequency */
+#define I2C_MASTER_TX_BUF_DISABLE   0                           /*!< I2C master doesn't need buffer */
+#define I2C_MASTER_RX_BUF_DISABLE   0                           /*!< I2C master doesn't need buffer */
+#define I2C_MASTER_TIMEOUT_MS       1000
+
+#define MPU6886_ADDR 0x68
+
+// MPU6886 Registers
+#define MPU6886_PWR_MGMT_1     0x6B
+#define MPU6886_WHO_AM_I       0x75
+#define MPU6886_ACCEL_XOUT_H   0x3B
+#define MPU6886_GYRO_XOUT_H    0x43
+#define MPU6886_TEMP_OUT_H     0x41
+#define MPU6886_ACCEL_CONFIG   0x1C
+#define MPU6886_GYRO_CONFIG    0x1B
+
+// Sensitivity scales
+#define ACCEL_SO_2G  16384.0f
+#define ACCEL_SO_4G   8192.0f
+#define ACCEL_SO_8G   4096.0f
+#define ACCEL_SO_16G  2048.0f
+
+#define GYRO_SO_250DPS  131.0f
+#define GYRO_SO_500DPS   65.5f
+#define GYRO_SO_1000DPS  32.8f
+#define GYRO_SO_2000DPS  16.4f
+
+#define TEMP_SO 326.8f
+#define TEMP_OFFSET 25.0f
+
+// Scale factors
+#define SF_M_S2 9.80665f
+#define SF_RAD_S 0.017453292519943f
+
+typedef struct {
+    float x;
+    float y;
+    float z;
+} vec3_t;
+
+typedef struct {
+    i2c_port_t i2c_port;
+    uint8_t address;
+    float accel_div;
+    float gyro_div;
+    vec3_t gyro_offset;
+    vec3_t accel_offset;
+} mpu6886_t;
+
+static esp_mqtt_client_handle_t s_mqtt_client = NULL;
+
+// Function declarations
+esp_err_t mpu6886_init(mpu6886_t *dev, i2c_port_t i2c_port);
+esp_err_t mpu6886_read_accel(mpu6886_t *dev, vec3_t *accel);
+esp_err_t mpu6886_read_gyro(mpu6886_t *dev, vec3_t *gyro);
+esp_err_t mpu6886_read_temp(mpu6886_t *dev, float *temp);
+esp_err_t mpu6886_calibrate_gyro(mpu6886_t *dev, int samples, int delay_ms);
+esp_err_t mpu6886_calibrate_accel(mpu6886_t *dev, int samples, int delay_ms);
+
+#endif