How many devices can be hooked up to one PC Bluetooth adapter at a time?
The internet is filled with conflicting information because a lot of it applies to different scenarios.
General background:
Firstly, there's a paired device and a connected device and then an actively communicating device. Your links above confuse these and no distinction, but there is a difference in functionality. A device can be paired, but not connected. Similarly, it can be connected but not transmitting. Think of a paired device as a saved wireless network that you're not connected to.
Then there are host devices and client devices. This is a generalization, but consider PCs, mobile phones, and tablets (and consoles) to be hosts, and headsets, controllers, mice, keyboards, etc. to be clients.
Then there's profiles, a profile indicating a type of connection (e.g. audio, HID, etc.)
With that in mind, the following apply:
In general, host devices support up to 7 simultaneously connected devices and a practically unlimited number of paired. Host devices are like a wireless router - you can connect many different devices at a time.
Client devices typically support a limited number of pairings, anywhere between 1 and 5, and only one single connection. They act like a wireless client - you can save many different networks but only connect to one at a time.
Some profiles only support one connection at a time on some devices - for example, some Bluetooth speakers can only connect to one computer at a time. A phone for example usually can only connect to one HSP (headset) at a time but can connect multiple HIDs (keyboards, mice, etc.).
Also, to explain/clarify some of your links/references:
- All Bluetooth adapters can support 7 devices, period.
Mostly true - the standards only allow up to seven simultaneous connections on a normal device. But you can pair any number of devices.
- You can hook up 7 devices, but only if they're all different types of devices.
False, but in some scenarios, you cannot simultaneously use two devices with the same Bluetooth profile. This generally applies to audio devices only (i.e. headsets) which may be all that some people are familiar with. For example, a phone can connect to one headset, or one music stream, or one of each, but not two headsets or two speakers. A PC can, however, connect to many phones at a time.
- You can hook up unlimited devices, no restrictions. (source - a Bluetooth Dongle tech-support)
False. You can usually pair unlimited devices on a host, but you cannot connect to them all simultaneously (again, think of the number of saved wireless networks, that aren't all connected at the same time)
- Only devices that support "multipoint functionality" can have multiple hooked up at once, and the choice of adapter doesn't make a difference.
Partly true. This only applies to client devices, such as headsets, controllers, keyboards, etc.. These limited devices can only connect to one host at a time if they do not have multipoint. A host can accept multiple clients even if those clients do not support multipoint.
- Only Bluetooth 4.1 adapters support multiple devices.
False. No idea where he got this from, it's plain rubbish.
- You can only use one device per Bluetooth adapter.
False. Pretty much everything in that entire statement is wrong.
So the final answer is yes, you can connect four controllers (clients) to one adapter (host) at a time. Even without the above information, it's fairly obvious as per @oldmud0's answer,
if [controller] uses Bluetooth, then how does the PlayStation establish a connection to all 4 controllers with a single radio [if Bluetooth didn't support it]?
Before I begin answering the question, think about this: if DualShock uses Bluetooth, then how does the PlayStation establish a connection to all 4 controllers with a single radio?
I use Scarlet.Crush's SCP drivers, and they seem to have great Bluetooth support (I use regular USB).
They require sacrificing one Bluetooth dongle to install SCP drivers on it, which replace the original Bluetooth drivers/stack (meaning the dongle will be dedicated to connecting DualShock controllers and nothing more).
The fact that plural in "controllers" is used frequently in the documentation confirms that you are able to connect all four controllers into a single dongle.
Due to the controller's hardware limitations (4 lights) and SCP's own limitations as a result, you can only have up to four controllers connected at once.
Since a concurrent connection to 4 devices are supported by a majority of Bluetooth radios (the forum post above lists them out) and this does not even come near to the spec's hard limit of 7, there is no doubt you will be able to connect all 4 controllers with a single dongle, regardless of whether they are DS3 or DS4, given that everything is correctly configured and paired up.
I think this is much more complex than a single answer.
There are many different types of Bluetooth connections, not all of these connections are interchangeable.
It also depends heavily upon which version of Bluetooth is being used in the devices, both the reciever for the PC and the controller.
As you can see from the Bluetooth 4.2 specification, which is 2,772 pages, it is quite complex.
Bluetooth 4.2 specification document:
https://www.bluetooth.org/DocMan/handlers/DownloadDoc.ashx?doc_id=286439
I doubt a definitive answer can be given to this question as to all Bluetooth devices in all scenarios.
I would however in this case as it's quite a simple scenario, purchase a single Bluetooth adapter and try to connect four controllers. I suspect that it will work from what I have deduced from the Bluetooth specification but I would ensure that you purchase a 4.2 Bluetooth adapter.
Apple Website FAQ
The official Bluetooth specifications state seven is the maximum number of Bluetooth devices that can be connected at once. However, three to four devices is a practical limit, depending on the types of devices and profiles are used. Some devices require more Bluetooth data, so they are more demanding than other devices. Data-intensive devices may reduce the total number of devices that can be active at the same time. If a Bluetooth device becomes slow to connect or does not perform reliably, reduce the total number of connected devices.
Apple Website Bluetooth FAQ
As can be seen from the official Apple website they state that the maximum number of connected devices is 7. The official Bluetooth spec says that up to 255 sleeping devices can be connected. This would indicate that the maximum number of parallel active connections is 7, however due to the complexity of the connections and amount of data to be transferred in most scenarios the practical limit is 3 or 4. Bluetooth signal can also be effected largely by other household devices such as Wifi, Microwaves and Household Phones. A true answer to this would be difficult to come by in relation to your exact scenario due to the large number of variables, however we can see that theoretically seven devices can have active connections in parallel and as reported by Apple the practical limit in the majority of scenarios is 3 or 4.