I am trying to play audio from Raspbian to a bluetooth speaker using A2DP.
From looking at test/simple-endpoint in the bluez source, it appears that running it without arguments should register an endpoint with the A2DP_SOURCE_UUID of 0000110A-0000-1000-8000-00805F9B34FB. However, I don't see any of the endpoint's callback methods being called (SelectConfiguration/SetConfiguration) when using bluetoothctl to connect to a bluetooth speaker. I tried with two different types of bluetooth speakers.
If I instead run simple-endpoint in "sbcsink" mode, and then connect my phone to it, I do see the endpoint's methods called (SelectConfiguration/SetConfiguration). So endpoints appear to be working for the A2DP sink uuid, but not the source one.
I'm able to find a org.bluez.MediaTransport1 corresponding to the bluetooth speaker by iterating through dbus managed objects:
import dbus
bus = dbus.SystemBus()
manager = dbus.Interface(bus.get_object('org.bluez', '/'), 'org.freedesktop.DBus.ObjectManager')
for path, ifaces in manager.GetManagedObjects().items():
transport = ifaces.get('org.bluez.MediaTransport1')
if transport is None:
continue
transport_obj = dbus.Interface(bus.get_object('org.bluez', path), 'org.bluez.MediaTransport1')
(fd, read_mtu, write_mtu) = transport_obj.Acquire('w')
taken_fd = fd.take()
print(path, fd, taken_fd, read_mtu, write_mtu)
I'm able to write to the transport's file descriptor taken_fd, but I can't control the audio configuration like I think I would if the transport had been acquired via a org.bluez.MediaEndpoint1. Also this seems kinda hacky, I'm not sure this transport is meant for me to access in this way. I would expect to get access to the transport via MediaEndpoint1's SetConfiguration.
I observed this behavior with bluez 5.43 on Rasbian Stretch. I also tried updating to the latest bluez 5.50 and saw the same behavior.
What is the expected way to use bluez as an audio source?
I figured out the problem by running bluetoothd in debug mode, and found that SetConfiguration/SetConfiguration was being called on a previously registered endpoint with a path of /A2DP/SBC/Source/1. Searching online for this path led me to discover that it was associated with bluealsa, which was registering the endpoint on system startup, and then was receiving the media endpoint callbacks instead of my endpoint. After killing bluealsa, my audio source endpoint was then able to receive the media endpoint callbacks as expected.
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first of all: What i am trying to do is only for private interest.
I'd like to connect a AT-09/HM-10 BLE-Module with Firmware 6.01 to another device which provides also a BLE Module, which it is not based on the CC254X-Chip,
I am able to communicate with this Device using my Laptop with integrated Bluetooth, Linux and the bluepy-helper. I am also able to make a connection using the HM10 through a USB-RS232-Module and "Hterm", but after that quite Stuck in my progress.
By "reverse-engineering" the Android-Application for controlling this particular device i found a set of Commands, stored as Strings in Hex-Format. The Java-Application itself sends out the particular Command combined with a CRC16-Modbus-Value in addition with a Request (whatever it is), to a particular Service and Characteristic UUID.
I also have a Wireshark-Protocol pulled from my Android-Phone while the application was connected to the particular device, but i am unable to find the commands extracted from the .apk in this protocol.
This is where i get stuck. After making a connection and sending out the Command+CRC16-Value i get no response at all, so i am thinking that my intentions are wrong. I am also not quite sure how the HM-10-Firmware handles / maps the Service and Char-UUIDs from the destination device.
Are there probably any special AT-Commands which would fit my need?
I am absolutely not into the technical depths of Bluetooth and its communication layer at all. The only thing i know is that the HM-10 connects to a selected BLE-Device and after that it provides a Serial I/O and data flows between the endpoints.
I have no clue how and if it can handle Data flow to certain Service/Char UUIDs from the destination endpoint, althrough it seems to have built-in the GATT , l2cap-Services and so on. Surely it handles all the neccessary communication by itself, but i don´t know where i get access to the "front-end" at all.
Best regards !
I have an app that communicates with a bluetooth device, and I'm trying to replace that app with some code.
I tried using C# InTheHand nuget, Microsoft's Bluetooth LE Explorer, python's sockets and others to send data and see what happens.
But there's something I still don't understand - in each way using different libraries I saw in wireshark a different protocol: ATT, RFCOMM, L2CAP...
When I sniffed my bluetooth traffic from my phone using the app mentioned before, I saw mostly HCI_CMD protocol traffic.
How can I choose the protocol I want to send? Is there a simple package for that? something to read?
Do I need to build the packet myself? including headers and such?
Thank you!
Update:
Using Microsoft's Bluetooth LE Explorer I was able to send a packet that lit up my lamp, starting with 02010e10000c00040012(data)
Using bleak I was able to send a packet starting with 02010e10000c00040052(data)
the difference makes the lamp not ligh up and I'm not sure if I can change it via bleak as it's not part of the data I send
I think what you are showing is that bleak does a write without response while MS BLE Explorer does a write_with_response.
Looking at the Bleak documentation for write_gatt_char that seems to be consistent as response is False by default
write_gatt_char Parameters:
char_specifier (BleakGATTCharacteristic, int, str or UUID). The characteristic to write to, specified by either integer handle, UUID
or directly by the BleakGATTCharacteristic object representing it.
data (bytes or bytearray) – The data to send.
response (bool) – If write-with-response operation should be done. Defaults to False.
I would expect the following to have the desired effect:
await client.write_gatt_char(LIGHT_CHARACTERISTIC, b"\x55\xaa\x03\x08\x02\xff\x00\xff\xf5", True)
I am fairly new to working with Bluetooth and the ESP32 Bluetooth stack, so forgive me if I don't use the right terminology.
I can get the ESP-IDF Development example "A2DP_Source" working perfect only if I enable the headphones pairing mode first. After it is paired, and the bonding is stored in the Bluetooth, it will reconnect to the headphones without issue, but it then does not notify the app through the call back functions that it has connected. The app then continues to search for a bluetooth device and the audio streams sporadically, or not at all.
I've tried multiple speakers, and headphones, all with the same results.
I can see the bonded device list also and the device is there.
Is there callback function in the bluetooth stack that needs to be initialized to notify the app that the bluetooth connected to a previously paired device instead of just a device in pairing mode?
These are the three callback functions setup currently that run when connected through pairing mode, but don't run when the bluetooth connects in non-pairing mode.
...
/* register GAP callback function */
esp_bt_gap_register_callback(bt_app_gap_cb);
/* initialize AVRCP controller */
esp_avrc_ct_init();
esp_avrc_ct_register_callback(bt_app_rc_ct_cb);
/* initialize A2DP source */
esp_a2d_register_callback(&bt_app_a2d_cb);
esp_a2d_source_register_data_callback(bt_app_a2d_data_cb);
...
Any help or pointers would be appreciated. Thanks.
Did you mean ESP32 A2DP cannot connect a device without the push of a PAIR button?
The example "A2DP_Source" does not seem to connect the bonded device.
It just tries to discover the device with the certain name ("ESP_SPEAKER" in the original code) calling the function esp_bt_gap_start_discovery.
If the device is found, bt_app_gap_cb is called and then the connect to peer will start via esp_a2d_source_connect.
So I suggest fixing the code so as to connect peer instead of calling esp_bt_gap_start_discovery if there is any bonded device.
You can use the function esp_bt_gap_get_bond_device_list and find out the address of the bonded device which is required by esp_a2d_source_connect.
The API reference is available in https://docs.espressif.com/projects/esp-idf/en/latest/esp32/api-reference/bluetooth/esp_gap_bt.html and https://docs.espressif.com/projects/esp-idf/en/latest/esp32/api-reference/bluetooth/esp_a2dp.html.
Working through this problem more, I found that using C++ to call the native C code was the issue. I don't have a strong enough background in coding to understand the "why" it did not work, but once I returned all the code back to "C" it started working without issue. Hope this helps someone else who may make the same mistake.
I'm a newbie of BLE programming on android.
In my first apps using BLE on android, I have a big problem.
I got a ScanRecord from Apple Bluetooth Headset using this function.
#Override
public void onScanResult(int callbackType, ScanResult result)
and I got a manufacturer data using Apple corp, ID(0x4C).
after that, I don't know how to decode a manufacturer data.
I want to auxiliary bluetooth headset information such as battery info, direction info etc. but I don't know how to decode the manufacturer data.
I also searched Apple development document(https://developer.apple.com/accessories/Accessory-Design-Guidelines.pdf)
But that guide document didn't help me.
Anyway, anyone who tell me how to resolve this problem?!!?!
Thank you to read my question.
Ok so from your comment it looks like you scanned the device over BLE and want to use one of the services it offers to get information like battery info.
The first thing you will need to do establish a connection to the BLE device.
The scanresult you pasted has a method getDevice you'll need to call
After you get the device you can call its connectGatt method. This will attempt to connect your phone and BLE device.
The connectGatt method from step 2 requires a callback. When the connection is successful or unsuccessful the callback will fire onConnectionStateChanged. If successful it will have the success status. This method will also give you a gatt device we will use in step 4.
If step 3 was successful we can assume your phone is connected. The next thing we want to do is discover services. You do this by using the gatt devices discoverServices method.
When the services are discovered your callback will fire onServicesDiscovered. At this point you can now use services. Depending on the API of the headphones they'll want you to read, or subscribe to a services characteristic and descriptor. Since I don't know the API I can't help you further. But you'll end up needing to use one or more of the following:
setCharacteristicNotification
readCharacteristic
readDescriptor
And the value will return to your callback on. Keep in mind you must wait for the callback for each request before write/reading/subscribing to another characteristic or descriptor.
I am currently attempting to connect to multiple BLE devices using BlueZ 5.0 and Linux. I have one host BLE adapter and I have modified the gatttool to connect and perform this function. If I run an instance of the modified gatttool, I successfully connect and receive notification data from the BLE device. If I run another instance of the modified gatttool and connect to another BLE device, this application starts receiving notification data from both BLE devices and the initial application no longer receives any data. I believe this is due to the socket setup, where both applications are configuring their sockets to the same address and PSM (the newest instance receives the data whereas the other is starved). Is there a way to prevent this condition? Ideally, I want one application to connect to multiple devices. I assume that the application can only have one socket for the reason that multiple sockets will have the same issue as the multiple instances above. My BLE device is a TI CC2540 keyfob acting as a heartrate monitor.
I started an answer so I could have more space...
I'm using a combination of Python and C to get my code to work, so my "code" may look funny because it could be from either. Also, I used Bluez 4 as the 5 didn't support the kernel I was using. Let me know if there's an issue and I can clarify.
It seems like there's several ways of doing things, but I ended up opening separate sockets for different tasks. You can open a single socket and then set the socket options to take filtering off and you should get all the packets in one place. However, that was my initial way of doing it and I found that my connections would die within seconds.
To scan for connections I opened a socket(AF_BLUETOOTH, SOCK_RAW, BTPROTO_HCI) then did a bind on device 0. (there's a function called hci_get_route to get an available device number) You can then call hci_le_set_scan_parameters to set options, setsockopt(SOL_HCI, HCI_FILTER, filter) to just get LE scan events, and then called hci_le_set_scan_enable to turn on scanning.
Each device connection was made with a socket(AF_BLUETOOTH, SOCK_SEQPACKET, BTPROTO_L2CAP) which you then tell to connect to a particular device by calling connect on the socket with a struct sockaddr_l2 that has the particular device address in it. On that socket you should only get packets from that device. (one caveat... I found that my dongle wouldn't allow a connection while active scanning was taking place.. I had to temporarily shut it off just before connecting and then turn it back on. Otherwise I got a BUSY error from errno)
After saying all that, though... I think the way you're supposed to do everything in Bluez 5 is to use DBUS. Unfortunately that wasn't really an option for what I was doing. The functions I mentioned are in the shared lib that apparently isn't installed by default in 5 (you have to explicitly ask for it to be installed with configure). They stopped installing the shared lib by default because they wanted to encourage people to use DBUS instead.
WE have combined the code from hcitool and gatttool. The code works well for 2 device (scan, hci_le_create_conn and gatt_connect). I believe there is no limitation on the number of devices used.
1 Start cmd_lescan (from hcitool.c)
2.For each device scanned -
cmd_lecc (from hcitool.c)
gatt_connect (from gatttool.c)
This way one process can manage multiple BLE device. We do not have to turn OFF the scanning, just have ignore non advertisement messages:
if (meta->subevent != 0x02)
continue;
Thanks and looking forward to comments.