Let's play with the configuration and evaluation of Raspberry Pi 3 + Bluetooth

Latest update time：2016-11-10

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Let's play with Raspberry Pi 3+. If you want to do your work well, you must first sharpen your tools.

In response to the needs of geeks, Raspberry Pi 3 supports WiFi and Bluetooth wireless communication technologies, providing more possibilities for IOT development. Today, let's test the Bluetooth function of Raspberry Pi 3.
After starting Raspberry Pi 3 and entering the Raspbian system desktop environment, a Bluetooth icon is displayed in the upper right corner of the desktop, as shown in the red box in the figure below.

Right-click on the Bluetooth icon to pop up a submenu with four menu options: “Turn Off Bluetooth”, “Make Discoverable”, “Add Device…”, and “Remove Device…”

Click the "Add Device..." submenu option to enter the Bluetooth device search interface. Turn on the Bluetooth of your phone and enable the detection function so that the Raspberry Pi can find it. After finding the device, select the phone in the Add New Device interface and click the Pair button to pair it.

A confirmation window will pop up during the pairing process, click OK to confirm.

After pairing is successful, the following window pops up. Analysis suggests that there is a problem with the SDP. Let's capture the log and analyze it. To analyze the Bluetooth data packet protocol, we need a software to assist in the analysis: Frontline. Go to http://www.fte.com/ to download the official website and install the Frontline installation package locally on Windows.
http://www.fte.com/support/CPAS- ... %20BPA%20600&iid=21 Download address.

Enter the developer options on your phone, turn on the developer options, and turn on the Bluetooth data packet log.

Click Make Discoverable in the Bluetooth submenu of the Raspberry Pi, then turn on the Bluetooth of your mobile phone and scan. You can scan the Raspberry Pi Bluetooth device, and the device name is raspberrypi(AD55).

Click to pair. After pairing is complete, check the profiles supported by the Raspberry Pi Bluetooth and find that only the shared contacts service is available, as shown in the figure below.

Copy the btsnoop_hci.log file in the mobile phone to the computer, change the suffix to .cfa file, and double-click the btsnoop_hci.cfa file to open it.

After analyzing the packet, we can see that the BlueZ used by the Raspbian operating system supports Bluetooth spec 4.1.

However, in the inquiry result, only AVRCP and GAP profiles are supported.

The result obtained in SDP is that only AVRCP and GAP profiles are supported, which leads to disconnection after SDP is completed.

The system's built-in Bluetooth management software is not very powerful. In order to make it easier to use, install Blueman. Blueman is a GTK Bluetooth manager that can efficiently manage the BlueZ API and simplify device connection and operation.
sudo apt-get install blueman

When testing file sending, the Raspberry Pi can send files to the mobile phone, but the mobile phone cannot send files to the Raspberry Pi. The problem is that the Raspberry Pi SDP does not contain the service record of the OPP profile.

Summarize:

The Bluetooth function of the Raspberry Pi Raspbian operating system is not yet perfect, at least the user experience is very poor, and there are still many problems. If you want to support OPP, A2DP, DUN and other profiles, you need to configure them yourself, and the configuration process is also very complicated.

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