蓝牙¶
EC-A1684JD4 支持无线蓝牙，可以通过 hciconfig -a 命令显示蓝牙设备信息：
linaro@bm1684:~$ hciconfig -a
hci0: Type: Primary Bus: USB
BD Address: 20:57:9E:BA:7C:EC ACL MTU: 1021:8 SCO MTU: 255:16
UP RUNNING
RX bytes:650 acl:0 sco:0 events:41 errors:0
TX bytes:2170 acl:0 sco:0 commands:41 errors:0
Features: 0xff 0xff 0xff 0xfa 0xdb 0xbd 0x7b 0x87
Packet type: DM1 DM3 DM5 DH1 DH3 DH5 HV1 HV2 HV3
Link policy: RSWITCH HOLD SNIFF PARK
Link mode: SLAVE ACCEPT
Name: 'bm1684'
Class: 0x000000
Service Classes: Unspecified
Device Class: Miscellaneous,
HCI Version: 4.2 (0x8) Revision: 0xaba8
LMP Version: 4.2 (0x8) Subversion: 0xa0cd
Manufacturer: Realtek Semiconductor Corporation (93)
注意的是，如果打印如下错误信息：
Can't open HCI socket.: Address family not supported by protocol
则可能是可加载模块的依赖性出现问题，此时重新加载依赖性，并软重启即可：
sudo -i
depmod -a
reboot
查看当前是主设备还是从设备：
linaro@bm1684:~$ hciconfig hci0 lm
hci0: Type: Primary Bus: USB
BD Address: 20:57:9E:BA:7C:EC ACL MTU: 1021:8 SCO MTU: 255:16
Link mode: SLAVE ACCEPT # 从设备
启动 PulseAudio 服务作为用于媒体设备：
linaro@bm1684:~$ pulseaudio --start --log-target=syslog
连接蓝牙设备步骤如下:
（1）启动蓝牙管理工具：
linaro@bm1684:~$ bluetoothctl
[NEW] Controller 20:57:9E:BA:7C:EC bm1684 [default]
（2）上电蓝牙控制器：
[bluetooth]# power on
Changing power on succeeded
（3）将蓝牙代理设置为默认值：
[bluetooth]# agent on
Agent registered
[bluetooth]# default-agent
Default agent request successful
（4）打开可被其他蓝牙设备发现：
[bluetooth]# discoverable on
Changing discoverable on succeeded
[CHG] Controller 20:57:9E:BA:7C:EC Discoverable: yes
（5）此时在智能手机就能发现 EC-A1684JD4 蓝牙设备，手机点击后就能配对上去：
[NEW] Device A4:90:CE:DF:64:4F iQOO Neo6 SE
[CHG] Device A4:90:CE:DF:64:4F Modalias: bluetooth:v001Dp1200d1436
[CHG] Device A4:90:CE:DF:64:4F UUIDs: 00001105-0000-1000-8000-00805f9b34fb
[CHG] Device A4:90:CE:DF:64:4F UUIDs: 0000110a-0000-1000-8000-00805f9b34fb
[CHG] Device A4:90:CE:DF:64:4F UUIDs: 0000110c-0000-1000-8000-00805f9b34fb
[CHG] Device A4:90:CE:DF:64:4F UUIDs: 0000110e-0000-1000-8000-00805f9b34fb
[CHG] Device A4:90:CE:DF:64:4F UUIDs: 00001112-0000-1000-8000-00805f9b34fb
[CHG] Device A4:90:CE:DF:64:4F UUIDs: 00001115-0000-1000-8000-00805f9b34fb
[CHG] Device A4:90:CE:DF:64:4F UUIDs: 00001116-0000-1000-8000-00805f9b34fb
[CHG] Device A4:90:CE:DF:64:4F UUIDs: 0000111f-0000-1000-8000-00805f9b34fb
[CHG] Device A4:90:CE:DF:64:4F UUIDs: 0000112d-0000-1000-8000-00805f9b34fb
[CHG] Device A4:90:CE:DF:64:4F UUIDs: 0000112f-0000-1000-8000-00805f9b34fb
[CHG] Device A4:90:CE:DF:64:4F UUIDs: 00001132-0000-1000-8000-00805f9b34fb
[CHG] Device A4:90:CE:DF:64:4F UUIDs: 00001200-0000-1000-8000-00805f9b34fb
[CHG] Device A4:90:CE:DF:64:4F UUIDs: 00001800-0000-1000-8000-00805f9b34fb
[CHG] Device A4:90:CE:DF:64:4F UUIDs: 00001801-0000-1000-8000-00805f9b34fb
[CHG] Device A4:90:CE:DF:64:4F UUIDs: 2c042b0a-7f57-4c0a-afcf-1762af70257c
[CHG] Device A4:90:CE:DF:64:4F UUIDs: 8fa9c715-bd1f-596c-a1b0-13162b15c892
[CHG] Device A4:90:CE:DF:64:4F ServicesResolved: yes
[CHG] Device A4:90:CE:DF:64:4F Paired: yes
[CHG] Device A4:90:CE:DF:64:4F ServicesResolved: no
[CHG] Device A4:90:CE:DF:64:4F Connected: no
[CHG] Controller 20:57:9E:BA:7C:EC Discoverable: no
（6）连接手机设备：
[bluetooth]# connect A4:90:CE:DF:64:4F
Attempting to connect to A4:90:CE:DF:64:4F
[CHG] Device A4:90:CE:DF:64:4F Connected: yes
Connection successful
[CHG] Device A4:90:CE:DF:64:4F ServicesResolved: yes
[iQOO Neo6 SE]#
（7）把手机设备设置成信任：
[iQOO Neo6 SE]# trust A4:90:CE:DF:64:4F
[CHG] Device A4:90:CE:DF:64:4F Trusted: yes
Changing A4:90:CE:DF:64:4F trust succeeded
蓝牙音频¶
蓝牙音频可以使用 bluez-alsa 工具，这是一个蓝牙音频 ALSA 后端实用程序。
安装 bluez-alsa 工具¶
EC-A1684JD4 默认没有安装该工具，用户需要自行编译安装，这里演示 1.3.0 版本的步骤，如下：
（1）下载源码包：https://github.com/Arkq/bluez-alsa/releases/tag/v1.3.0
（2）安装依赖：
sudo apt install -y libasound2-dev libbluetooth-dev libglib2.0-dev libsbc-dev libfdk-aac-dev pkgconf
（3）解压：
tar xzvf bluez-alsa-1.3.0.tar.gz
cd bluez-alsa-1.3.0
（4）编译与安装：
autoreconf --install
mkdir build && cd build
../configure --enable-aac --enable-debug
make && make install
音频测试¶
安装完成后可以连接蓝牙耳机或者音箱进行音乐播放，首先将蓝牙配置成主设备模式：
sudo hciconfig hci0 lm master
开启 bluez-alsa 服务，注意 PulseAudio 服务与 bluez-alsa 是互斥的：
# 去掉 PulseAudio 进程
killall pulseaudio
# 开启 bluez-alsa 服务用于连接蓝牙耳机或音响
bluealsa -p a2dp-source -p hsp-ag &
连接蓝牙耳机：
[bluetooth]# connect 0C:AE:BD:9B:BB:5C
Attempting to connect to 0C:AE:BD:9B:BB:5C
[CHG] Device 0C:AE:BD:9B:BB:5C Connected: yes
Connection successful
[CHG] Device 0C:AE:BD:9B:BB:5C ServicesResolved: yes
[EDIFIER LolliPods 2022版]#
另外开启一个登录，执行以下命令播放音频：
aplay -D bluealsa:HCI=hci0,DEV=0C:AE:BD:9B:BB:5C,PROFILE=a2dp example.wav
关于 bluez-alsa 更多使用可参考源代码仓库：https://github.com/Arkq/bluez-alsa/tree/v1.3.0。
文件收发¶
蓝牙文件收发可以使用 OBEX 协议，它以对象模型封装信息数据，以会话协议规范传输应用。
在 Linux 中需要用到 Obex 服务，首先 EC-A1684JD4 根据前面的步骤连接好蓝牙设备，然后开启 Obex 守护进程，并设置接收的目录为 /home/linaro/：
/usr/lib/bluetooth/obexd -r /home/linaro -a -d &
使用 obex push 服务¶
首先将蓝牙配置成主设备模式：
sudo hciconfig hci0 lm master
查找手机 Obex Push 服务的通道：
linaro@bm1684:~$ sdptool search --bdaddr A4:90:CE:DF:64:4F OPUSH
Searching for OPUSH on A4:90:CE:DF:64:4F ...
Service Name: OBEX Object Push
Service RecHandle: 0x1000d
Service Class ID List:
"OBEX Object Push" (0x1105)
Protocol Descriptor List:
"L2CAP" (0x0100)
"RFCOMM" (0x0003)
Channel: 12
"OBEX" (0x0008)
Profile Descriptor List:
"OBEX Object Push" (0x1105)
Version: 0x0102
Searching for OPUSH on A4:90:CE:DF:64:4F ...
Service Search failed: Invalid argument
可以看到通道为 12，紧接着就能把文件 push 到手机上：
linaro@bm1684:~$ obexftp --nopath --noconn --uuid none --bluetooth A4:90:CE:DF:64:4F --channel 12 --put sn.txt
Suppressing FBS.
Connecting..\done
Sending "sn.txt".../done
Disconnecting..-done
此时手机端就可看到是否接收文件的弹窗。
使用 obexctl 交互命令行¶
以下演示 EC-A1684JD4 收文件的步骤：
（1）设备端（从设备）开启 obex 服务：
root@firefly:~# systemctl --user start obex
（2）进入交互命令行：
root@firefly:~# obexctl
[NEW] Client /org/bluez/obex
（3）连接 EC-A1684JD4 （主设备）：
[obex]# connect 20:57:9E:BA:7C:EC
Attempting to connect to 20:57:9E:BA:7C:EC
...
[NEW] Session /org/bluez/obex/client/session2 [default]
[NEW] ObjectPush /org/bluez/obex/client/session2
（4）发送文件：
[20:57:9E:BA:7C:EC]# send /root/test.txt
Attempting to send /root/test.txt to /org/bluez/obex/client/session1
[NEW] Transfer /org/bluez/obex/client/session1/transfer1
Transfer /org/bluez/obex/client/session1/transfer1
Status: queued
Name: test.txt
Size: 0
Filename: /root/test.txt
Session: /org/bluez/obex/client/session1
[CHG] Transfer /org/bluez/obex/client/session1/transfer1 Status: complete
（5）查看 EC-A1684JD4 的 /home/linaro/目录有 test.txt 文件：
linaro@bm1684:~$ ls -l test.txt
-rw------- 1 linaro linaro 0 Nov 25 15:49 test.txt