树莓派上开启和配置蓝牙

1. 更新系统软件包

   sudo apt update
   sudo apt upgrade
   

2. 安装相关的软件包

   sudo apt install bluetooth pi-bluetooth bluez blueman mplayer
   

3. 启动蓝牙命令行工具

   bluetoothctl
   

4. 开启代理

   agent on
   

5. 扫描设备

   scan on
   

   通过扫描设备，可以检索到对应设备的MAC地址，之后可以用该设备的MAC地址来与树莓派进行配对，扫描结果如下

   [bluetooth]# scan on
   Discovery started
   [CHG] Controller E4:5F:01:26:55:90 Discovering: yes
   [NEW] Device 4A:E4:8E:E3:BC:54 4A-E4-8E-E3-BC-54
   [CHG] Device 9C:19:C2:4D:88:DC Name: Redmi Buds 3
   

6. 树莓派与蓝牙设备进行配对

   [bluetooth]# pair 9C:19:C2:4D:88:DC
   Attempting to pair with 9C:19:C2:4D:88:DC
   [CHG] Device 9C:19:C2:4D:88:DC Connected: yes
   

   配对成功（这里我使用树莓派与我的蓝牙耳机进行配对）

7. 连接设备（第一次配对会自动连接，否则需要执行以下命令连接）

   [Redmi Buds 3]# connect 9C:19:C2:4D:88:DC
   Attempting to connect to 9C:19:C2:4D:88:DC
   [CHG] Device 9C:19:C2:4D:88:DC Connected: yes
   Connection successful
   

   连接成功（如需退出可输入quit退出蓝牙）

8. 连接成功后另外开启一个终端，通过mplayer播放音乐

   pi@raspberrypi:~/Desktop $ mplayer music.mp3
   MPlayer 1.4 (Debian), built with gcc-10 (C) 2000-2019 MPlayer Team
   
   Playing music.mp3.
   libavformat version 58.45.100 (external)
   Audio only file format detected.
   Load subtitles in ./
   ==========================================================================
   Opening audio decoder: [mpg123] MPEG 1.0/2.0/2.5 layers I, II, III
   AUDIO: 44100 Hz, 2 ch, s16le, 320.0 kbit/22.68% (ratio: 40000->176400)
   Selected audio codec: [mpg123] afm: mpg123 (MPEG 1.0/2.0/2.5 layers I, II, III)
   ==========================================================================
   AO: [pulse] 44100Hz 2ch s16le (2 bytes per sample)
   Video: no video
   Starting playback...
   A:   5.9 (05.9) of 256.0 (04:16.0)  1.8%
   

   可以使用alsamixer命令来控制声音的大小