modified notes about esp_gap_ble_api

components/bt/host/bluedroid/api/esp_gap_ble_api.c

@@ -72,7 +72,7 @@ esp_err_t esp_ble_gap_set_scan_params(esp_ble_scan_params_t *scan_params)
  return (btc_transfer_context(&msg, &arg, sizeof(btc_ble_gap_args_t), NULL, NULL) == BT_STATUS_SUCCESS ? ESP_OK : ESP_FAIL);
 }
 
-esp_err_t esp_ble_gap_start_scanning(uint32_t duration)
+esp_err_t 0(uint32_t duration)
 {
  btc_msg_t msg = {0};
  btc_ble_gap_args_t arg;

components/bt/host/bluedroid/api/include/api/esp_bt_defs.h

@@ -166,15 +166,42 @@ typedef enum {
 /// Bluetooth peer irk
 #define ESP_PEER_IRK_LEN 16
 
-/// Bluetooth device address
-typedef uint8_t esp_bd_addr_t[ESP_BD_ADDR_LEN];
-
-/// BLE device address type
+// Bluetooth device address
+typedef uint8_t esp_bd_addr_t[ESP_BD_ADDR_LEN]; /*!< Bluetooth device address. Typically 6 bytes (48 bits). */
+
+/**
+ * @brief LE device address type
+ * - More details in Spec BLUETOOTH CORE SPECIFICATION Version 5.4 Vol 4, Part E.
+ * - Public Device Address: A 48-bit extended unique identifier that remains constant after being set at the factory. It can be retrieved using `esp_bt_dev_get_address`.
+ * - Static Random Address: Remains constant once initialized with `esp_ble_gap_set_rand_addr`, and only changes when the device is power cycled.
+ * - Non-Resolvable Private Address (NRPA): Can be changed at any time using `esp_ble_gap_set_rand_addr`.
+ * - Resolvable Private Address (RPA):
+ * - The RPA will auto-update when `CONFIG_BT_BLE_RPA_TIMEOUT`.
+ * - Using `esp_ble_gap_config_local_privacy` to enable RPA generation and resolution.
+ * - The controller uses the Local IRK (Identity Resolving Key) to generate an RPA as the device's own address.
+ * - The controller uses the peer address to find the corresponding Local IRK in the resolving list.
+ * - To use a unique Local IRK for different peer devices, enable the `CONFIG_BT_BLE_SMP_ID_RESET_ENABLE` configuration and bond with the peer device, then specify the peer address.
+ * - To use a fixed Local IRK, set the peer address to all zeros.
+ * 
+ * | address [47:46] | Address Type | Corresponding API |
+ * |-----------------|-----------------------------------------------|---------------------------------------------|
+ * | 0b00 | Resolvable private address <br> Address (RPA) | setting `owner address type` to 0x02 or0x03 |
+ * | 0b01 | Non-Resolvable Private <br> Address (NRPA) | esp_ble_gap_addr_create_nrpa |
+ * | 0b11 | Static Random Address | esp_ble_gap_addr_create_static |
+ * - We use the Big-Endian form to store addresses, e.g.{0xc0, 0xde, 0x52, 0x00, 0x00, 0x01}, the first two bits are `11`.
+ */
 typedef enum {
- BLE_ADDR_TYPE_PUBLIC = 0x00, /*!< Public Device Address */
- BLE_ADDR_TYPE_RANDOM = 0x01, /*!< Random Device Address. To set this address, use the function esp_ble_gap_set_rand_addr(esp_bd_addr_t rand_addr) */
- BLE_ADDR_TYPE_RPA_PUBLIC = 0x02, /*!< Resolvable Private Address (RPA) with public identity address */
- BLE_ADDR_TYPE_RPA_RANDOM = 0x03, /*!< Resolvable Private Address (RPA) with random identity address. To set this address, use the function esp_ble_gap_set_rand_addr(esp_bd_addr_t rand_addr) */
+ BLE_ADDR_TYPE_PUBLIC = 0x00, /*!< Public Device Address. */
+ BLE_ADDR_TYPE_RANDOM = 0x01, /*!< Random Device Address. 
+ - Random Device Address contains Non-resolvable private address (NRPA) and Static random address.
+ - To set this address, use the function `esp_ble_gap_set_rand_addr`. */
+ BLE_ADDR_TYPE_RPA_PUBLIC = 0x02, /*!< Resolvable Private Address (RPA) with public identity address.
+ - Controller generates Resolvable Private Address based on the local IRK from the resolving list.
+ If the resolving list contains no matching entry, use the public address. */
+ BLE_ADDR_TYPE_RPA_RANDOM = 0x03, /*!< Resolvable Private Address (RPA) with random identity address. 
+ - To set this address, use the function `esp_ble_gap_set_rand_addr`.
+ - Controller generates Resolvable Private Address based on the local IRK from the resolving list.
+ If the resolving list contains no matching entry, use the random address from `esp_ble_gap_set_rand_addr`. */
 } esp_ble_addr_type_t;
 
 /// white list address type