I am working on application that requires fast switching between two bluetooth headphones.
That would be just a part of larger software/hardware kit meant for improving communication with hearing impaired people. When sound level is below certain threshold headphones should be off. As soon as sound loudness exceeds threshold headphone should be turned on. I have already done something similar for one headset only. Now I need to expand that with possibility of using two headsets simultaneously. Is there any way, hardware or software, to achieve this ?
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I'm trying to connect several bluetooth devices with Raspberry PI to use them as speakers.
I'm using RetroPie as a distribution, because of the tests I've done it's the only one that matches and allows continuous synchronization with several bluetooth devices at the same time.
However, the system only detects the first device that connects as a sound card, the rest keep the bluetooth synchronization active, but it does not interpret them as audio cards even though it is indicated by blueman-manager.
Is there anything I can do to keep all devices synchronized and supported as audio cards?
Palm,
even so this a old post, it is not yet closed.
As I just got the same issue, here my answer.
What you try to do is to connect mutliple audio sreaming services (Speakers) to 1 audio bluetooth source, that is not possible like this. Therefore your PC only connects to the first box.
You could try multiple bluetooth dongles, but then you run into the timing issue with audio stream syncronization between the boxes.
The only solution is to use Bluetooth 4.1 upwards master-slave services.
Therefore the Speakers need to be connected to each other and seen as 1 device from the PC. In that mode the stream is skewed to ensure syncronous playing.
Many new Bluetooth speakers support this mode.
Hope that helped.
I need to feed two headphones from one audio source. In the past, I've done this with one of the many Bluetooth transmitters that support two headphones. I assume the transmitter did this by simply opening two Bluetooth connections, perhaps by using two Bluetooth chips.
My transmitter has recently broken, so it's time to buy another. I've seen various opinions on whether Bluetooth 5 has a new protocol feature that supports two headphones. If true, I'll look at transmitters supporting that feature. Presumably, since the protocol would be affected, I would also need new compatible headphones.
If anyone has definitive information on Bluetooth 5 support for two headphones, I'd like to see it. And, it would be useful it you can reference the specific Bluetooth 5 profile that defines the feature, or perhaps the section of the Bluetooth spec.
Thanks,
Ron
They say that Bluetooth Hearing Aid Profile will support multi-user HQ audio and audio broadcast, but it is not adopted yet.
I have a bluetooth headset. When connecting it to Windows 10, it installs two profiles in Playback devices list:
Hands-Free. (HSP profile)
Stereo. (A2DP profile)
The Second one (Stereo) is set to be the "Default Device" and the "Default Communication Device" on the system.
When I start any program that uses the mic (recorder, chat, VoIP Calls, gaming, etc.) The sound suddenly stops working And I can only use the mic until I stop the recorder or the call.
To enable the sound again I need to make the Hands-Free (HSP) profile handle both input and output (sound and mic). Unfortunately, HSP gives really poor sound quality.
I want to know If there is a way, using code, I can change Bluetooth behavior so the two profiles work simultaneously. One handles the sound and one handles the mic so I can have high quality sound and use the mic at the same time.
You will probably never find a solution. I had the same problem (I was trying to create a walkie talkie with 2 headsets connected to the same smartphone).
On Windows (but also on Android) you can't access directly to a BT-microphone or BT-speaker because it is automatically detected as BT headset and the OS take the control of the device.
Your app can then access the OS-device and not directly the hardware device. The only OS able to do that was Symbian I think which had the most BT-protocols. On Windows you will probably never be able to do that and on Android you have to write your own A2DP-protocol if you want to access the device directly without OS interference.
So sad...
Luckily, under windows you can define different devices for communications and sound.
So, you have two choices:
Choosing Hands-free for both mic/speaker only for communication (which will switch back to A2DP after the call/teams).
Choosing another mic for communication which allow you to still use the speaker profile even in communication.
That is a bluetooth restriction : A2DP (high quality audio) cannot be use simultaneously with HFP (hands-free profile)
I am working on a project where I need to attach a sensor to the computer like laser sensor or an infrared sensor, to use in a foul line detection. Basically the idea is, if someone steps on the foul line, the laser or infrared will be blocked by person's foot, and the laser/infrared won't be received by the receiver, causing the sensor to send a signal to the computer.
The problem is, I don't know where to start something like this. How would I go about attaching a sensor to a normal computer (like a normal PC that we use)? If someone could direct me into a direction or has any inputs, that would be really appreciated. Thanks a lot!
You may want to look at Arduino (http://www.arduino.cc/). It is an open-source microcontroller that can be used along with a computer and is designed to be hooked up to various types of sensors. It also has an extremely helpful, active support community.
There are several approaches to the task of bringing the sensor signal into a PC (to take advantage of PC's computing power, good user interface, connectivity to the web).
Look for integrated sensors that have an interface for attaching to a PC (RS-232, USB, Ethernet). For example, you may find something useful by googling photodetector USB.
There are I/O (input/output) devices for PC. They have analog and digital inputs and outputs. Look up LabJack, National Instruments USB-6008 and dozen other types of commercial USB I/O boxes.
Connect sensors to a microcontroller (uC), then connect uC to the PC through a USB or RS-232 or Bluetooth (the list goes on). This involves more hardware. You'll need to write firmware for the microcontroller too.
Obviously, which approach to choose depends on your skills (or willingness to acquire new ones), timing, budget, team structure (if it's a team effort).
You could use a photo-transistor and a Yocto-Knob. The Yocto-knob is an USB device able to quickly detect resistivity changes, you just have to connect the photo-transistor to it. Here is an application which looks pretty similar to yours: they use a light barrier to detect and photograph a fast object:
http://www.yoctopuce.com/EN/article/how-to-drive-a-camera-shutter-automatically
Does anyone know how a bluetooth device could pick up the discoverable devices' device IDs in range?
I am ideally looking for the simplest solution that involves the smallest implimentation of the bluetooth protocols.
A starting point would be good, I just wish to create a device that can store all the device ids of nearby bluetooth devices with minimal power consumption, preferably just using radio frequencies and not SDP and whatever else.
If you can't help me with this, please can you help me find good reading material for low level bluetooth (step by step) communication. The reading online is so high level that I cant work out what is actually sent, when.
Laalto nailed the answer from the Bluetooth spec/stack POV, but your question implies your looking for a stand-alone Bluetooth device - not just a laptop app scanning surrounding devices.
I can only speak for the BT chips that the company I work for manufactures (Cambridge Silicon Radio - CSR) but our chips can do that pretty much out of the box. Our chips have an on-board Virtual Machine sandbox that allows access to the firmware functions and Bluetooth stack of the chip. You can easily write a C code app to run in the virtual machine sandbox, on chip, that periodically scans for discoverable devices around, grab their ids and then download them when connected via USB or Serial, or maybe over BT when a device connects to the listener directly.
www.csr.com and www.csrsupport.com for chips, dev-kits, design references, etc.. etc...
You probably want a module with the extra HW (UARTs, USB etc...) as well as just the chip but you could implement this with something the size of a BlueTooth USB or probably smaller.
It would really help to know more about what your trying to achieve, why you want something that just scans the surrounding bluetooth devices and how big the device needs to be.
Sorry if this sounds like advertising. For balance: Broadcom make BT chips too!
The Bluetooth specs from http://www.bluetooth.org are a good starting place for low-level information. You need an account to access the specs, but you can create one for free.
Basically what you need to do is to go into Inquiry mode periodically and grab the response packets as they arrive. The more time you spend in Inquiry mode, the more likely you will discover devices in range: discoverable devices enter the Inquiry Scan mode only relatively rarely; it takes some time (10.24s at least with older Bluetooth versions) to scan all the possible frequencies in the Inquiry/Inquiry Scan frequency hopping schemes. And even then you can have suboptimal radio conditions.
For implementation I suggest you at least start with existing Bluetooth libraries such as BlueZ and do not attempt to create your own from scratch.