【android bluetooth 协议分析 01】【HCI 层介绍 5】【SetEventMask命令介绍】

1. HCI_Set_Event_Mask 命令作用

5	2025-04-24 15:55:53.350452	host	controller	HCI_CMD	12	Sent Set Event Mask

Bluetooth HCI Command - Set Event Mask
    Command Opcode: Set Event Mask (0x0c01)
        0000 11.. .... .... = Opcode Group Field: Host Controller & Baseband Commands (0x03)
        .... ..00 0000 0001 = Opcode Command Field: Set Event Mask (0x001)
    Parameter Total Length: 8
    .... ...1 = Inquiry Complete: true (0x1)
    .... ..1. = Inquiry Result: true (0x1)
    .... .1.. = Connect Complete: true (0x1)
    .... 1... = Connect Request: true (0x1)
    ...1 .... = Disconnect Complete: true (0x1)
    ..1. .... = Auth Complete: true (0x1)
    .1.. .... = Remote Name Req Complete: true (0x1)
    1... .... = Encrypt Change: true (0x1)
    .... ...1 = Change Connection Link Key Complete: true (0x1)
    .... ..1. = Master Link Key Complete: true (0x1)
    .... .1.. = Read Remote Supported Features: true (0x1)
    .... 1... = Read Remote Ver Info Complete: true (0x1)
    ...1 .... = QoS Setup Complete: true (0x1)
    1... .... = Hardware Error: true (0x1)
    .... ...1 = Flush Occurred: true (0x1)
    .... ..1. = Role Change: true (0x1)
    .... 1... = Mode Change: true (0x1)
    ...1 .... = Return Link Keys: true (0x1)
    ..1. .... = PIN Code Request: true (0x1)
    .1.. .... = Link Key Request: true (0x1)
    1... .... = Link Key Notification: true (0x1)
    .... ...1 = Loopback Command: true (0x1)
    .... ..1. = Data Buffer Overflow: true (0x1)
    .... .1.. = Max Slots Change: true (0x1)
    .... 1... = Read Clock Offset Complete: true (0x1)
    ...1 .... = Connection Packet Type Changed: true (0x1)
    ..1. .... = QoS Violation: true (0x1)
    .1.. .... = Page Scan Mode Change: true (0x1)
    1... .... = Page Scan Repetition Mode Change: true (0x1)
    .... ...1 = Flow Specification Complete: true (0x1)
    .... ..1. = Inquiry Result With RSSI: true (0x1)
    .... .1.. = Read Remote Ext. Features Complete: true (0x1)
    .... 1... = Synchronous Connection Complete: true (0x1)
    ...1 .... = Synchronous Connection Changed: true (0x1)
    ..1. .... = Sniff Subrate: true (0x1)
    .1.. .... = Extended Inquiry Result: true (0x1)
    1... .... = Encryption Key Refresh Complete: true (0x1)
    .... ...1 = IO Capability Request: true (0x1)
    .... ..1. = IO Capability Response: true (0x1)
    .... .1.. = User Confirmation Request: true (0x1)
    .... 1... = User Passkey Request: true (0x1)
    ...1 .... = Remote OOB Data Request: true (0x1)
    ..1. .... = Simple Pairing Complete: true (0x1)
    1... .... = Link Supervision Timeout Changed: true (0x1)
    .... ...1 = Enhanced Flush Complete: true (0x1)
    .... .1.. = User Passkey Notification: true (0x1)
    .... 1... = Keypress Notification: true (0x1)
    [Response in frame: 6]
    [Command-Response Delta: 0.756ms]

2. BLE 支持相关说明

在 Event_Mask 的第 61 位（即第 8 字节的第 5 位）是一个关键：

3. Event_Mask 各位的详细含义（按位表格）

Event_Mask 是一个 **8 字节（64 位）的位掩码，每个 bit 控制一个事件类型。如下是规范中定义的位：

注意：

• 默认值 是 bit 0~44 设为 1（值为 0x00001FFFFFFFFFFF），表示支持经典蓝牙核心事件。

• 若想启用 BLE，必须额外设置 bit 61 为 1。

4. 典型使用流程（含 BLE）

一个 BLE 主机设备通常在初始化时使用以下 HCI 命令序列：

1. HCI_Reset
2. HCI_Write_LE_Host_Support (0x01) 声明主机支持 BLE
3. HCI_Set_Event_Mask 使能 bit 61（LE Meta Event）
4. HCI_LE_Set_Event_Mask 控制哪些 BLE 子事件开启（如连接、广播报告等）

5. aosp 示例代码片段

  static constexpr uint64_t kDefaultEventMask = 0x3dbfffffffffffff;
  static constexpr uint64_t kDefaultLeEventMask = 0x000000004d02fe7f;
  
// system/gd/hci/controller.cc

struct Controller::impl {

  void Start(hci::HciLayer* hci) {
...
    le_set_event_mask(kDefaultLeEventMask);
    set_event_mask(kDefaultEventMask);
    write_le_host_support(Enable::ENABLED, Enable::DISABLED);

...
}


  void set_event_mask(uint64_t event_mask) {
    std::unique_ptr<SetEventMaskBuilder> packet = SetEventMaskBuilder::Create(event_mask);
    hci_->EnqueueCommand(std::move(packet), module_.GetHandler()->BindOnceOn(
                                                this, &Controller::impl::check_status<SetEventMaskCompleteView>));
  }

• 在初始化 Controller 模块时， 在 Controller::impl::Start 函数中就会调用 set_event_mask 函数去设置
• 这里设置的 mask 为 0x3dbfffffffffffff

• 这里默认 [61] 位是设置了 1: 表示支持 ble

6. 注意事项

7. 总结