蓝牙¶
EC-A1688JD4 支持无线蓝牙，可以通过 hciconfig -a 命令显示蓝牙设备信息：
linaro@sophon:~$ hciconfig -a
hci0: Type: Primary Bus: USB
BD Address: F0:35:75:A7:E2:88 ACL MTU: 1021:6 SCO MTU: 255:12
UP RUNNING PSCAN ISCAN
RX bytes:1050 acl:0 sco:0 events:61 errors:0
TX bytes:2735 acl:0 sco:0 commands:61 errors:0
Features: 0xff 0xff 0xff 0xfa 0xdb 0xbf 0x7b 0x87
Packet type: DM1 DM3 DM5 DH1 DH3 DH5 HV1 HV2 HV3
Link policy: RSWITCH HOLD SNIFF PARK
Link mode: SLAVE ACCEPT
Name: 'sophon'
Class: 0x0c0000
Service Classes: Rendering, Capturing
Device Class: Miscellaneous,
HCI Version: 5.1 (0xa) Revision: 0x1ac7
LMP Version: 5.1 (0xa) Subversion: 0x2999
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@sophon:~$ hciconfig hci0 lm
hci0: Type: Primary Bus: USB
BD Address: F0:35:75:A7:E2:88 ACL MTU: 1021:6 SCO MTU: 255:12
Link mode: SLAVE ACCEPT # 从设备
启动 PulseAudio 服务作为用于媒体设备：
linaro@sophon:~$ 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@sophon:~$ bluetoothctl
Agent registered
[CHG] Controller F0:35:75:A7:E2:88 Pairable: yes
（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 is already 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 F0:35:75:A7:E2:88 Discoverable: yesyes
（5）此时在智能手机就能发现 EC-A1688JD4 蓝牙设备，手机点击后就能配对上去：
[NEW] Device 34:1C:F0:40:59:55 小黎的 Redmi K30 Ultr
Request confirmation
[agent] Confirm passkey 062794 (yes/no): yes
[CHG] Device 34:1C:F0:40:59:55 Modalias: bluetooth:v0046p1200d1436
[CHG] Device 34:1C:F0:40:59:55 UUIDs: 00001105-0000-1000-8000-00805f9b34fb
[CHG] Device 34:1C:F0:40:59:55 UUIDs: 0000110a-0000-1000-8000-00805f9b34fb
[CHG] Device 34:1C:F0:40:59:55 UUIDs: 0000110c-0000-1000-8000-00805f9b34fb
[CHG] Device 34:1C:F0:40:59:55 UUIDs: 00001112-0000-1000-8000-00805f9b34fb
[CHG] Device 34:1C:F0:40:59:55 UUIDs: 00001115-0000-1000-8000-00805f9b34fb
[CHG] Device 34:1C:F0:40:59:55 UUIDs: 00001116-0000-1000-8000-00805f9b34fb
[CHG] Device 34:1C:F0:40:59:55 UUIDs: 0000111f-0000-1000-8000-00805f9b34fb
[CHG] Device 34:1C:F0:40:59:55 UUIDs: 0000112f-0000-1000-8000-00805f9b34fb
[CHG] Device 34:1C:F0:40:59:55 UUIDs: 00001132-0000-1000-8000-00805f9b34fb
[CHG] Device 34:1C:F0:40:59:55 UUIDs: 00001200-0000-1000-8000-00805f9b34fb
[CHG] Device 34:1C:F0:40:59:55 UUIDs: 00001800-0000-1000-8000-00805f9b34fb
[CHG] Device 34:1C:F0:40:59:55 UUIDs: 00001801-0000-1000-8000-00805f9b34fb
[CHG] Device 34:1C:F0:40:59:55 ServicesResolved: yes
[CHG] Device 34:1C:F0:40:59:55 Paired: yes
Authorize service
[agent] Authorize service 0000110d-0000-1000-8000-00805f9b34fb (yes/no): yes
[CHG] Device 34:1C:F0:40:59:55 UUIDs: 00001105-0000-1000-8000-00805f9b34fb
[CHG] Device 34:1C:F0:40:59:55 UUIDs: 0000110a-0000-1000-8000-00805f9b34fb
[CHG] Device 34:1C:F0:40:59:55 UUIDs: 0000110c-0000-1000-8000-00805f9b34fb
[CHG] Device 34:1C:F0:40:59:55 UUIDs: 0000110d-0000-1000-8000-00805f9b34fb
[CHG] Device 34:1C:F0:40:59:55 UUIDs: 00001112-0000-1000-8000-00805f9b34fb
[CHG] Device 34:1C:F0:40:59:55 UUIDs: 00001115-0000-1000-8000-00805f9b34fb
[CHG] Device 34:1C:F0:40:59:55 UUIDs: 00001116-0000-1000-8000-00805f9b34fb
[CHG] Device 34:1C:F0:40:59:55 UUIDs: 0000111f-0000-1000-8000-00805f9b34fb
[CHG] Device 34:1C:F0:40:59:55 UUIDs: 0000112f-0000-1000-8000-00805f9b34fb
[CHG] Device 34:1C:F0:40:59:55 UUIDs: 00001132-0000-1000-8000-00805f9b34fb
[CHG] Device 34:1C:F0:40:59:55 UUIDs: 00001200-0000-1000-8000-00805f9b34fb
[CHG] Device 34:1C:F0:40:59:55 UUIDs: 00001800-0000-1000-8000-00805f9b34fb
[CHG] Device 34:1C:F0:40:59:55 UUIDs: 00001801-0000-1000-8000-00805f9b34fb
（6）连接手机设备：
[bluetooth]# connect 34:1C:F0:40:59:55
Attempting to connect to 34:1C:F0:40:59:55
[CHG] Device 34:1C:F0:40:59:55 Connected: yes
（7）把手机设备设置成信任：
[小黎的 Redmi K30 Ultr]# trust 34:1C:F0:40:59:55
[CHG] Device 34:1C:F0:40:59:55 Trusted: yes
Changing 34:1C:F0:40:59:55 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-A1688JD4 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）安装依赖：
sudo apt-get install git automake build-essential libtool pkg-config python3-docutils
sudo apt-get install libasound2-dev libbluetooth-dev libdbus-1-dev libglib2.0-dev libsndfile1-dev libsbc-dev
sudo apt-get install libudev-dev libical-dev libreadline-dev
# 安装 fdk-aac
wget https://downloads.sourceforge.net/opencore-amr/fdk-aac-2.0.1.tar.gz
tar -zxvf fdk-aac-2.0.1.tar.gz
cd fdk-aac-2.0.1/
autoreconf -fiv
sudo ./configure --prefix=/usr --disable-shared
sudo make
sudo make install
（2）下载 bluez-alsa 并编译安装：
wget https://github.com/arkq/bluez-alsa/archive/refs/tags/v1.3.0.tar.gz
tar -xf v1.3.0.tar.gz
cd bluez-alsa-1.3.0
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-A1688JD4 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@sophon:~$ 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@sophon:~$ 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-A1688JD4 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-A1688JD4 （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-A1688JD4 的 /home/linaro/目录有 test.txt 文件：
linaro@sophon:~$ ls -l test.txt
-rw------- 1 linaro linaro 0 Nov 25 15:49 test.txt