This section provides a description of how to use the demo application to connect an audio source to it and communicate over Bluetooth.

The STM32 board is ready to connect right after it starts, to create this connection, either the source or the sink can initialize it.

The A2DP source can be any application that can transmit audio. For our example, we will use an android phone as the demo. In order to connect to the sink, the source needs the sink Bluetooth address or name.

Sink Terminal

1. The Bluetooth address can be found at the beginning of the demo application or by typing GetLocalAddress, in this case we can see the bluetooth address.
2. The Sink name can be found by typing GetLocalName and the terminal will print the default name of the application AUDDemo
   Figure 2-2 AUDDemo Name and Address
   
   Source Phone

   After the data of the sink for the connection is known:

3. Open the Bluetooth settings menu on the android phone (Settings->Bluetooth).
4. Hit on search for devices. The phone should begin looking for other Bluetooth devices.
   Figure 2-3 AUDDemo Searching for Devices
5. An AUDDemo or A2DPDemo should appear like shown below in the picture. Click on the device to begin pairing.
   Figure 2-4 AUDDemo TI Device Name
6. Enter PIN password and remember it, in the example we use 0000.
   Figure 2-5 AUDDemo Demo Pin
   
   Sink terminal
7. In the Sink terminal there is a request for PIN code that to allow the pairing to complete, enter PINCodeResponse 0000.
   Figure 2-6 AUDDemo Pin Code Response
8. After the devices are paired, the device should show connected on the phone side and on the STM32.
   Figure 2-7 AUDDemo Phone Connected
   Figure 2-8 AUDDemo Connected From Source
9. You can now control the audio of the phone from the STM32 board.

1. In Order to connect to the source, the sink must find it first with inquiry command, type inquiry.
   Figure 2-9 AUDDemo Inquiry Sink
2. The inquiry command generates a list of all the devices in range.
3. In order to connect to the source use the OpenRemoteSteam command with the index of the bluetooth address you want, in our case we connect to index 2, so we type OpenRemoteStream 2.
   Figure 2-10 AUDDemo Open Remote Stream
   
   Sink Terminal
4. Enter PIN password and remember it. In the example we use 0000.
   Figure 2-11 AUDDemo Pin Sink
   Sink terminal
5. In the Sink terminal there is a request for PIN code that to allow the pairing to complete, enter PINCodeResponse 0000.
   Figure 2-12 AUDDemo Pin Code Response Sink
6. After the devices are paired, the device should show connected on the phone side and on the STM32.
   Figure 2-13 AUDDemo Phone Connect from Sink
   Figure 2-14 AUDDemo Connected From Sink

Now, after the sink and the source are connected we can start controlling the audio of the source from the sink.

1. Open any music application in the source, in the sink, in order to control the audio use SendPassThroughCommand Command and a parameter for the command. the command can be Pause = 0, Play = 1, Stop = 2, Vol. up = 3 and Vol. Down = 4.
   Note: Volume (Vol.) commands might not work with your device.
   Figure 2-15 AUDDemo Send Pass Through Command
2. Type SendPassThroughCommand 1. A track will start playing on the devices.
   Figure 2-16 AUDDemo Send Pass Through Command 1
3. Type SendPassThroughCommand 2. A track will stop playing on the devices.
   Figure 2-17 AUDDemo Send Pass Through Command 2
4. In order to change the Stream format: Sample rate and Mono/Stereo, use the ChangeStreamFormat command and a value which represent the supported format index that is needed.
5. The supported sink formats and their indexes can be displayed by typing QuerySupportedFormats.
   Note: The connection must be in suspend in order to work. ChangeStreamFormat might not work with your device.
   Figure 2-18 AUDDemo Change Stream Format

   The First Number is the index that you choose, the second number is the sample rate in Hz and the third number represents 1 = Mono, 2 = Stereo.

6. In order to change the Stream State: Stopped or Started, use the Changestreamstate command and a value which represent the stream state 0 = Stopped, 1 = Started. When the Command Changestreamstate 0 is sent, the devices will enter to suspend mode of A2DP.
   Note: Changestreamstate might not work with your device.
   Figure 2-19 AUDDemo Change Stream State
7. The command ChangeConnectionMode enable the sink to allow automatically or manual connections or disallow connection, use the ChangeConnectionMode command and a value which represent the connection mode Automatic Accept = 0, Automatic Reject = 1, Manual Accept = 2.
   Figure 2-20 AUD Demo Change Connection Mode