Bluetooth: Direct Advertising
概述
本示例演示了 BLE 的定向广播功能。在没有 bonded 的时候，程序发送常规性广播。一旦 bond 成功， 后续每次设备重新启动将发送指向 bonded 设备的定向广播。除此之外，程序还提供了两项BLE characteristics：支持 bonded 的写操作和不支持 bonded 的读操作。
特别注意 iOS 设备不支持接收定向广播功能，具体信息请参考 “Accessory Design Guidelines for Apple Devices”.
环境要求
支持 BLE 功能的开发板
使能 Privacy 特性的中央功能的 BLE 设备。例如，wm-iot-sdk 开发板或者一部智能手机
编译和烧录
示例位置：
examples/bluetooth/direct_adv
编译、烧录等操作，具体参考 快速入门 章节 。
运行结果
I/bt_smp [0.024] LE SC enabled
I/bt_hci_core [0.156] No ID address. App must call settings_load()
I/direct_adv [0.162] Bluetooth initialized
I/bt_hci_core [0.168] Identity: 28:6D:CE:01:02:03 (public)
I/bt_hci_core [0.172] HCI: version 4.2 (0x08) revision 0x0709, manufacturer 0x070c
I/bt_hci_core [0.180] LMP: version 4.2 (0x08) subver 0x0709
I/direct_adv [0.190] Advertising successfully started