解析代码WORD Length; switch(Type) { case 1://设备地址 Length = sizeof( StateRecord.Device_ID ); break; case 2://继电器状态 Length = sizeof( StateRecord.RelayCtrRecord ); break; case 3://隔离CT控制状态 Length = sizeof( StateRecord.CT_CtrRecord ); break; case 4://电磁阀控制状态 Length = sizeof( StateRecord.ValveCtrRecord ); break; default: Length = 0; break; } return Length;

这段代码是一个函数，根据给定的Type值返回不同的长度值。根据Type的不同，代码会进入不同的case分支，并给Length赋上相应的值。如果Type是1，Length会被赋上StateRecord.Device_ID的大小；如果Type是2，Length会被赋上StateRecord.RelayCtrRecord的大小；如果Type是3，Length会被赋上StateRecord.CT_CtrRecord的大小；如果Type是4，Length会被赋上StateRecord.ValveCtrRecord的大小；如果Type不是1、2、3、4中的任何一个，Length会被赋值为0。最后，函数返回Length的值。

相关问题

nrf52830蓝牙加密是怎么一回事？用sdk或者其他代码来讲解

nRF52830 是一款支持加密的蓝牙芯片，可以使用 Nordic 官方提供的 SDK 或者其他库来实现加密功能。下面是一个使用 Nordic SDK 实现 nRF52830 蓝牙加密的代码示例：

#include "nrf_ble_gatt.h"
#include "nrf_ble_qwr.h"
#include "nrf_sdh_ble.h"
#include "nrf_sdh_soc.h"
#include "nrf_ble_scan.h"
#include "nrf_ble_conn_params.h"
#include "nrf_ble_gq.h"
#include "nrf_crypto.h"
#include "nrf_crypto_error.h"

#define DEVICE_NAME                     "MyDevice"        // 设备名称
#define APP_BLE_OBSERVER_PRIO           3                // BLE事件观察者优先级

static ble_gap_sec_params_t m_sec_params;               // 安全参数
static ble_gap_conn_params_t m_conn_params;             // 连接参数
static uint16_t m_conn_handle = BLE_CONN_HANDLE_INVALID;// 连接句柄

void ble_stack_init(void)
{
    ret_code_t err_code;

    // 初始化 SoftDevice
    err_code = nrf_sdh_enable_request();
    APP_ERROR_CHECK(err_code);

    // 配置 SoftDevice 协议栈
    nrf_sdh_ble_default_cfg_set(APP_BLE_OBSERVER_PRIO);
    
    // 配置 BLE GAP
    ble_gap_conn_sec_mode_t sec_mode;
    BLE_GAP_CONN_SEC_MODE_SET_OPEN(&sec_mode);
    err_code = sd_ble_gap_device_name_set(&sec_mode, (const uint8_t *)DEVICE_NAME, strlen(DEVICE_NAME));
    APP_ERROR_CHECK(err_code);

    // 配置安全参数
    memset(&m_sec_params, 0, sizeof(m_sec_params));
    m_sec_params.bond = 1;
    m_sec_params.mitm = 1;
    m_sec_params.lesc = 1;
    m_sec_params.keypress = 0;
    m_sec_params.io_caps = BLE_GAP_IO_CAPS_NONE;
    m_sec_params.oob = 0;
    m_sec_params.min_key_size = 7;
    m_sec_params.max_key_size = 16;

    // 配置连接参数
    memset(&m_conn_params, 0, sizeof(m_conn_params));
    m_conn_params.min_conn_interval = MSEC_TO_UNITS(20, UNIT_1_25_MS);
    m_conn_params.max_conn_interval = MSEC_TO_UNITS(75, UNIT_1_25_MS);
    m_conn_params.slave_latency = 0;
    m_conn_params.conn_sup_timeout = MSEC_TO_UNITS(4000, UNIT_10_MS);

    // 初始化 BLE GATT
    err_code = nrf_ble_gatt_init(&m_gatt, NULL);
    APP_ERROR_CHECK(err_code);

    // 初始化 BLE QWR
    err_code = nrf_ble_qwr_init(&m_qwr, &m_qwr_buffer);
    APP_ERROR_CHECK(err_code);

    // 初始化 BLE Scan
    err_code = nrf_ble_scan_init(&m_scan, NULL, NULL);
    APP_ERROR_CHECK(err_code);

    // 初始化 BLE Connection Parameters
    err_code = nrf_ble_conn_params_init(&m_conn_params);
    APP_ERROR_CHECK(err_code);

    // 初始化 BLE GQ
    err_code = nrf_ble_gq_init(&m_ble_gq, ble_gatt_evt_handler);
    APP_ERROR_CHECK(err_code);

    // 启用 BLE Stack
    err_code = nrf_sdh_ble_enable(&m_sec_params);
    APP_ERROR_CHECK(err_code);
}

void ble_gap_evt_handler(ble_gap_evt_t const * p_gap_evt, void * p_context)
{
    ret_code_t err_code;

    switch (p_gap_evt->evt_id)
    {
        case BLE_GAP_EVT_CONNECTED:
            m_conn_handle = p_gap_evt->conn_handle;
            break;

        case BLE_GAP_EVT_DISCONNECTED:
            m_conn_handle = BLE_CONN_HANDLE_INVALID;
            break;

        case BLE_GAP_EVT_SEC_PARAMS_REQUEST:
            err_code = sd_ble_gap_sec_params_reply(m_conn_handle, BLE_GAP_SEC_STATUS_SUCCESS, &m_sec_params, NULL);
            APP_ERROR_CHECK(err_code);
            break;

        case BLE_GAP_EVT_AUTH_STATUS:
            if (p_gap_evt->params.auth_status.auth_status == BLE_GAP_SEC_STATUS_SUCCESS)
            {
                // 认证通过，加密连接
                err_code = nrf_ble_gatt_authenticate(m_conn_handle, NULL);
                APP_ERROR_CHECK(err_code);
            }
            break;

        case BLE_GAP_EVT_CONN_PARAM_UPDATE_REQUEST:
            err_code = sd_ble_gap_conn_param_update(m_conn_handle, &p_gap_evt->params.conn_param_update_request.conn_params);
            APP_ERROR_CHECK(err_code);
            break;

        default:
            // 不处理其他事件
            break;
    }
}

void ble_gatt_evt_handler(nrf_ble_gatt_t * p_gatt, nrf_ble_gatt_evt_t const * p_evt)
{
    ret_code_t err_code;

    switch (p_evt->evt_id)
    {
        case NRF_BLE_GATT_EVT_MTU_CHANGED:
            break;

        case NRF_BLE_GATT_EVT_ATT_MTU_UPDATED:
            break;

        case NRF_BLE_GATT_EVT_DATA_LENGTH_UPDATED:
            break;

        case NRF_BLE_GATT_EVT_ATT_EXCHANGE_MTU_REQUEST:
            err_code = nrf_ble_gatt_att_mtu_reply(p_gatt, p_evt->conn_handle, BLE_GATT_ATT_MTU_DEFAULT);
            APP_ERROR_CHECK(err_code);
            break;

        case NRF_BLE_GATT_EVT_HVX:
            break;

        case NRF_BLE_GATT_EVT_WRITE:
            break;

        case NRF_BLE_GATT_EVT_READ:
            break;

        case NRF_BLE_GATT_EVT_TIMEOUT:
            break;

        case NRF_BLE_GATT_EVT_EXCHANGE_MTU_RSP:
            break;

        case NRF_BLE_GATT_EVT_CHAR_DISC_RSP:
            break;

        case NRF_BLE_GATT_EVT_DESC_DISC_RSP:
            break;

        case NRF_BLE_GATT_EVT_CHAR_VALS_READ_RSP:
            break;

        case NRF_BLE_GATT_EVT_WRITE_RSP:
            break;

        case NRF_BLE_GATT_EVT_HANDLE_VALUE_INDICATION_CONFIRMED:
            break;

        default:
            // 不处理其他事件
            break;
    }
}

void ble_stack_start(void)
{
    ret_code_t err_code;

    // 启动 BLE Scan
    err_code = nrf_ble_scan_start(&m_scan);
    APP_ERROR_CHECK(err_code);

    // 启动 BLE Connection Parameters
    err_code = nrf_ble_conn_params_enable();
    APP_ERROR_CHECK(err_code);
}

在上述代码中，我们使用了 Nordic SDK 提供的函数来初始化蓝牙协议栈、配置安全参数、配置连接参数、初始化 GATT、初始化 QWR、初始化 BLE Scan、初始化 BLE Connection Parameters 等，最终启动 BLE Stack，实现了 nRF52830 蓝牙加密功能。

需要注意的是，在安全参数中我们设置了 mitm 和 lesc 为 1，这表示我们需要进行双向身份验证和安全连接。在 BLE_GAP_EVT_AUTH_STATUS 事件中，当认证成功时，我们通过调用 nrf_ble_gatt_authenticate 函数来进行加密连接，从而实现了蓝牙加密功能。

esp32 蓝牙启动流程_ESP32教你简单进行蓝牙串口调试

ESP32的蓝牙启动流程如下：

1. 初始化蓝牙协议栈

2. 配置蓝牙参数，如设备名称、服务UUID等

3. 注册蓝牙事件回调函数

4. 启动蓝牙广播

5. 开启蓝牙可见性

6. 等待连接

以下是一个简单的ESP32蓝牙串口调试的示例：

#include "esp_bt.h"
#include "esp_bt_main.h"
#include "esp_gap_ble_api.h"

#define GATTS_TAG "GATTS_DEMO"
#define TEST_DEVICE_NAME "ESP32_BLE_UART"
#define TEST_MANUFACTURER_DATA_LEN 17

/* The max length of characteristic value. When the gatt client write or prepare write,
*  the data length must be less than MAX_VALUE_LENGTH.
*/
#define MAX_VALUE_LENGTH 500

/* Declare global variable */
static uint8_t test_manufacturer[TEST_MANUFACTURER_DATA_LEN] = {0x4c, 0x00, 0x02, 0x15, 0xE2, 0x0A, 0x39, 0xF4, 0x73, 0xF5, 0x4B, 0xC4, 0xA1, 0x2F, 0x17, 0xD1, 0xAD};
static uint8_t test_service_uuid128[32] = {
    /* LSB <--------------------------------------------------------------------------------> MSB */
    //first uuid, 16bit, [12],[13] is the value
    0x13, 0x2B, 0x01, 0x00, 0x00, 0x00, 0x10, 0x00, 0x80, 0x00, 0x00, 0x80, 0x5F, 0x9B, 0x34, 0xFB,
    //second uuid, 32bit, [12], [13], [14], [15] is the value
    0x14, 0x2B, 0x01, 0x00, 0x00, 0x00, 0x10, 0x00, 0x80, 0x00, 0x00, 0x80, 0x5F, 0x9B, 0x34, 0xFB,
};

static uint8_t test_service_uuid[16] = {
    /* LSB <--------------------------------------------------------------------------------> MSB */
    //first uuid, 16bit, [12],[13] is the value
    0x01, 0x2B,
    //second uuid, 32bit, [12], [13], [14], [15] is the value
    0x01, 0x2B, 0x01, 0x00, 0x00, 0x00, 0x10, 0x00, 0x80, 0x00, 0x00, 0x80, 0x5F, 0x9B, 0x34, 0xFB,
};

static uint8_t test_char_uuid[16] = {
    /* LSB <--------------------------------------------------------------------------------> MSB */
    //first uuid, 16bit, [12],[13] is the value
    0x02, 0x2B,
    //second uuid, 32bit, [12], [13], [14], [15] is the value
    0x02, 0x2B, 0x01, 0x00, 0x00, 0x00, 0x10, 0x00, 0x80, 0x00, 0x00, 0x80, 0x5F, 0x9B, 0x34, 0xFB,
};

static esp_gatt_char_prop_t test_property = 0;

static uint8_t char1_str[] = {0x11,0x22,0x33};
static esp_attr_value_t gatts_demo_char1_val = {
    .attr_max_len = MAX_VALUE_LENGTH,
    .attr_len     = sizeof(char1_str),
    .attr_value   = char1_str,
};

static uint16_t gatts_demo_handle_table[3];

/* Full Database Description - Used to add attributes into the database */
static const esp_gatts_attr_db_t gatt_db[HRS_IDX_NB] =
{
    // Service Declaration
    [IDX_SVC]        =
    {
        {ESP_GATT_AUTO_RSP},
        {ESP_UUID_LEN_16, (uint8_t *)&primary_service_uuid, ESP_GATT_PERM_READ,
            sizeof(test_service_uuid), sizeof(test_service_uuid), (uint8_t *)&test_service_uuid},
        ESP_GATT_UUID_PRI_SERVICE,
        ESP_GATT_PERM_READ,
        sizeof(test_service_uuid),
        sizeof(test_service_uuid),
        (uint8_t *)&test_service_uuid,
        0
    },
    /* Characteristic Declaration */
    [IDX_CHAR_READ]  =
    {
        {ESP_GATT_AUTO_RSP},
        {ESP_UUID_LEN_16, (uint8_t *)&character_declaration_uuid, ESP_GATT_PERM_READ,
            CHAR_DECLARATION_SIZE, CHAR_DECLARATION_SIZE, (uint8_t *)&test_property},
        ESP_GATT_UUID_CHAR_DECLARE,
        ESP_GATT_PERM_READ,
        CHAR_DECLARATION_SIZE,
        CHAR_DECLARATION_SIZE,
        (uint8_t *)&test_property,
        0
    },
    /* Characteristic Value */
    [IDX_CHAR_VAL_READ] =
    {
        {ESP_GATT_AUTO_RSP},
        {ESP_UUID_LEN_128, (uint8_t *)&test_char_uuid, ESP_GATT_PERM_READ,
            MAX_VALUE_LENGTH, sizeof(gatts_demo_char1_val), gatts_demo_char1_val.attr_value},
        ESP_UUID_LEN_128,
        ESP_GATT_PERM_READ,
        MAX_VALUE_LENGTH,
        sizeof(gatts_demo_char1_val),
        gatts_demo_char1_val.attr_value,
        0
    },
};

static esp_ble_adv_data_t adv_data = {
    .set_scan_rsp        = false,
    .include_name        = true,
    .include_txpower     = true,
    .min_interval        = 0x20,
    .max_interval        = 0x40,
    .appearance          = 0x00,
    .manufacturer_len    = TEST_MANUFACTURER_DATA_LEN,
    .p_manufacturer_data = test_manufacturer,
    .service_data_len    = 0,
    .p_service_data      = NULL,
    .service_uuid_len    = sizeof(test_service_uuid),
    .p_service_uuid      = test_service_uuid,
    .flag = (ESP_BLE_ADV_FLAG_GEN_DISC | ESP_BLE_ADV_FLAG_BREDR_NOT_SPT),
};

static esp_ble_adv_params_t adv_params = {
    .adv_int_min         = 0x20,
    .adv_int_max         = 0x40,
    .adv_type            = ADV_TYPE_IND,
    .own_addr_type       = BLE_ADDR_TYPE_PUBLIC,
    .peer_addr           = {0x00, 0x00, 0x00, 0x00, 0x00, 0x00},
    .peer_addr_type      = BLE_ADDR_TYPE_PUBLIC,
    .channel_map         = ADV_CHNL_ALL,
    .adv_filter_policy   = ADV_FILTER_ALLOW_SCAN_ANY_CON_ANY,
};

static void gap_event_handler(esp_gap_ble_cb_event_t event, esp_ble_gap_cb_param_t *param)
{
    switch (event) {
    case ESP_GAP_BLE_ADV_DATA_SET_COMPLETE_EVT:
        esp_ble_gap_start_advertising(&adv_params);
        break;
    case ESP_GAP_BLE_ADV_START_COMPLETE_EVT:
        if (param->adv_start_cmpl.status != ESP_BT_STATUS_SUCCESS) {
            ESP_LOGE(GATTS_TAG, "advertising start failed");
        }
        break;
    default:
        break;
    }
}

static void gatts_event_handler(esp_gatts_cb_event_t event, esp_gatt_if_t gatts_if, esp_ble_gatts_cb_param_t *param)
{
    switch (event) {
    case ESP_GATTS_REG_EVT:
        esp_ble_gap_set_device_name(TEST_DEVICE_NAME);
        esp_ble_gap_config_adv_data(&adv_data);
        break;
    case ESP_GATTS_CREAT_ATTR_TAB_EVT:
        if (param->add_attr_tab.status != ESP_GATT_OK){
            ESP_LOGE(GATTS_TAG, "create attribute table failed, error code=0x%x", param->add_attr_tab.status);
        }
        else if (param->add_attr_tab.num_handle != HRS_IDX_NB) {
            ESP_LOGE(GATTS_TAG, "create attribute table abnormally, num_handle (%d) \
                    doesn't equal to HRS_IDX_NB(%d)", param->add_attr_tab.num_handle, HRS_IDX_NB);
        }
        else {
            ESP_LOGI(GATTS_TAG, "create attribute table successfully, the number handle = %d\n",param->add_attr_tab.num_handle);
            memcpy(gatts_demo_handle_table, param->add_attr_tab.handles, sizeof(gatts_demo_handle_table));
            esp_ble_gatts_start_service(gatts_demo_handle_table[IDX_SVC]);
        }
        break;
    case ESP_GATTS_CONNECT_EVT:
        ESP_LOGI(GATTS_TAG, "ESP_GATTS_CONNECT_EVT");
        break;
    case ESP_GATTS_DISCONNECT_EVT:
        ESP_LOGI(GATTS_TAG, "ESP_GATTS_DISCONNECT_EVT");
        esp_ble_gap_start_advertising(&adv_params);
        break;
    case ESP_GATTS_WRITE_EVT:
        ESP_LOGI(GATTS_TAG, "ESP_GATTS_WRITE_EVT");
        break;
    case ESP_GATTS_MTU_EVT:
        ESP_LOGI(GATTS_TAG, "ESP_GATTS_MTU_EVT, MTU %d", param->mtu.mtu);
        break;
    case ESP_GATTS_CONF_EVT:
        ESP_LOGI(GATTS_TAG, "ESP_GATTS_CONF_EVT");
        break;
    case ESP_GATTS_EXEC_WRITE_EVT:
        ESP_LOGI(GATTS_TAG, "ESP_GATTS_EXEC_WRITE_EVT");
        break;
    case ESP_GATTS_START_EVT:
        ESP_LOGI(GATTS_TAG, "ESP_GATTS_START_EVT");
        break;
    case ESP_GATTS_STOP_EVT:
        ESP_LOGI(GATTS_TAG, "ESP_GATTS_STOP_EVT");
        break;
    case ESP_GATTS_OPEN_EVT:
        ESP_LOGI(GATTS_TAG, "ESP_GATTS_OPEN_EVT");
        break;
    case ESP_GATTS_CANCEL_OPEN_EVT:
        ESP_LOGI(GATTS_TAG, "ESP_GATTS_CANCEL_OPEN_EVT");
        break;
    case ESP_GATTS_CLOSE_EVT:
        ESP_LOGI(GATTS_TAG, "ESP_GATTS_CLOSE_EVT");
        break;
    case ESP_GATTS_LISTEN_EVT:
        ESP_LOGI(GATTS_TAG, "ESP_GATTS_LISTEN_EVT");
        break;
    case ESP_GATTS_CONGEST_EVT:
        ESP_LOGI(GATTS_TAG, "ESP_GATTS_CONGEST_EVT");
        break;
    case ESP_GATTS_UNREG_EVT:
    case ESP_GATTS_DELETE_EVT:
    default:
        break;
    }
}

void app_main()
{
    esp_err_t ret;

    ESP_LOGI(GATTS_TAG, "ESP_BLUETOOTH_BLE example started.");

    esp_bt_controller_config_t bt_cfg = BT_CONTROLLER_INIT_CONFIG_DEFAULT();
    ret = esp_bt_controller_init(&bt_cfg);
    if (ret) {
        ESP_LOGE(GATTS_TAG, "%s initialize controller failed\n", __func__);
        return;
    }

    ret = esp_bt_controller_enable(ESP_BT_MODE_BLE);
    if (ret) {
        ESP_LOGE(GATTS_TAG, "%s enable controller failed\n", __func__);
        return;
    }

    ret = esp_bluedroid_init();
    if (ret) {
        ESP_LOGE(GATTS_TAG, "%s init bluetooth failed\n", __func__);
        return;
    }

    ret = esp_bluedroid_enable();
    if (ret) {
        ESP_LOGE(GATTS_TAG, "%s enable bluetooth failed\n", __func__);
        return;
    }

    ret = esp_ble_gatts_register_callback(gatts_event_handler);
    if (ret){
        ESP_LOGE(GATTS_TAG, "gatts register error, error code = %x", ret);
        return;
    }

    ret = esp_ble_gap_register_callback(gap_event_handler);
    if (ret){
        ESP_LOGE(GATTS_TAG, "gap register error, error code = %x", ret);
        return;
    }

    ret = esp_ble_gatts_app_register(ESP_APP_ID);
    if (ret){
        ESP_LOGE(GATTS_TAG, "gatts app register error, error code = %x", ret);
        return;
    }

    esp_err_t local_mtu_ret = esp_ble_gatt_set_local_mtu(500);
    if (local_mtu_ret){
        ESP_LOGE(GATTS_TAG, "set local  MTU failed, error code = %x", local_mtu_ret);
    }

    ret = esp_ble_gatts_create_attr_tab(gatt_db, gatts_if, HRS_IDX_NB, ESP_APP_ID);
    if (ret){
        ESP_LOGE(GATTS_TAG, "create attr table failed, error code = %x", ret);
    }
}

在这个示例中，我们使用了ESP-IDF提供的蓝牙协议栈和GATT Server框架，实现了一个简单的GATT Server，并且开启了蓝牙广播和可见性，使得其他蓝牙设备可以扫描到并连接我们的设备。在连接建立后，我们可以向GATT Server中的特定Characteristic写入数据，也可以从特定Characteristic读取数据。