is there a way for a peripheral to determine to what central it is connected to?
Suppose i have a peripheral device that can connect to a PC, a Smartphone, or a smart TV, etc. The peripheral is an arduino based system, therefore has got some intelligence and i want it to behave in different ways according to what the central it is connected to is. What would be the best way to understand what the central is?
Thanks
There is no way to determine the connected central device type, the way you asked. One way to do is program your arduino to act differently as per the BD_ADDR addresses of the central device. But in this case, you need to know the addresses of all your central devices, and it works only with known set of devices. Also some central devices may not use public BD_ADDR addresses. For example Apple devices use random addresses. In this case you don't know the real BD_ADDR address, until your device pairs with central device. You can't rely on their names because Bluetooth device names can be changed.
Related
Is the Bluetooth address exchanged between two Bluetooth devices if no connection is made yet?
As when a device is in discovery mode, and you see for example a tv, headphones, or a different computer show up, is the Bluetooth address of that device being shared with the device making the inquiry, or are the others also getting the Bluetooth address of the inquiring device?
Alternatively, is the Bluetooth address only shared upon selection of the device for connection?
Thanks!
Edit: spelling
Advertising devices broadcast one-way. They do not know what devices have discovered them. Scanning for advertisements is passive. It does not require sending any packets, so neither the advertising device, nor other scanners in the area, will be aware of the scanning device.
Note that Bluetooth addresses are quite complex and varied, so how they are shared is not trivial. Devices have many kinds of addresses and change what they publicize frequently. But to the question of when an address (rather than the address) is shared, that is during connection.
I am considering automating the heating in my home via electronic radiator valves with Bluetooth. There will be 19 such valves. I therefore need several bluetooth devices (I am calling them hubs) which will interface to these 19 radiator valves, and allow me to communicate with them from a central PC. The PC will not be within Bluetooth distance of some of the radiators, so I need a device that can be connected to my ethernet LAN, and can then connect to each bluetooth radiator valve within reach and allow me to communicate with it from software on my central PC. I will need several of these devices. Questions:
Is what I'm suggesting technically possible?
Does a "bluetooth hub" like I'm suggesting exist? Please suggest any candidates that might do the job. Since I have to buy several of these I will be motivated by price to some extent. But also I don't want the hub to get in the way of communication between the radiators and the central host.
Any other helpful suggestions.
Thank you - Rowan
If you search the internet for the term "Bluetooth Gateway" you will probably find more solutions nearer to what you are looking for. A cost effective way of doing this would be using a Raspberry Pi Zero W (or WH). I am sure a ESP32 would be another good candidate.
I suspect your radiator values are Bluetooth Low Energy (BLE) so that is the way to build the gateway.
Looking into the future, this type of application might be done with Bluetooth Mesh
I am looking for a way to scan a device I own and discover "what it can do".
In other words, I'd like to know if a device is able to describe the way you have to communicate with it in order to build some application around it.
In my case it is a simple Christmas light that I'd like to play with but this could be used in different situations.
For classic bluetooth (BR/EDR):
When scanning for bluetooth devices (Inquiry), the bluetooth device will send an inquiry response (if it wants to be discovered) and maybe also an extended inquiry response (EIR). This EIR may already contain a list of services, the devices supports. This is a very fast way to get a picture of a remote device.
Moreover, the service discovery protocol (SDP) gives more information on a device. This takes some more steps. In SDP two devices can exchange their capabilites in kind of ping pong process.
For BLE:
After connecting a BLE device usually a service discovery takes place. The BLE peripheral (e.g. headset or a light) reports its capabilities to the central (e.g. smart phone). Some of these services have predefines functionalities. Additionally, it is free to the manufacturer to add custom services.
I'm not sure how to correctly phrase this question, as I'm just starting to learn Bluetooth and its ways, but... imagine holding in an iPhone or Android phone in your hand in a large building with many rooms. You pair your device with a Bluetooth master device via an antenna in that room. Then once you move from room to room, your device communicates with other antennas throughout the building, but the device treats it as one pairing.
Is this at all possible? Was Bluetooth developed with this in mind at all?
Would this still work if the antennas were wireless? My idea is for devices to communicate with nodes via Bluetooth, and nodes interact with central base via wi-fi/local router.
Also, third random question: how does using BLE affect any of this?
Please tell me if I'm crazy! Thanks!
Bluetooth 4.0 BLE allows for a slave to connect to one master. 4.1 BLE allows for more than one connection, but I don't know if anything implements that yet.
Either way, there's no sort of "roaming" method pairing devices like with wifi access points with the same SSID. BLE however doesn't require pairing like regular Bluetooth, so you could just connect to a new access point each time you lose a connection.
You can also communicate via advertising packets from the "antenna" in each room. This would facilitate information being passed from those rooms to the phone, but not the other way around. This is basically how you communicate with BLE when you don't pair/connect devices and is how iBeacons work.
If you're writing the software yourself, and installing it in the building and on the phone, then I think it should be totally possible. Bluetooth devices can detect the distance and direction of other bluetooth devices. So if both devices are running software that is designed to, and grants permission to do so, it should be no-big-deal to programmatically auto-reconnect to the new nearest antenna whenever one becomes significantly closer than the one that your phone is currently connected to. As for software that already does this that you wouldn't have to develop from scratch yourself, no idea.
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.