I have this doubt. For example, I have a Smart Wrist Band (measures pulse, body temp), a Smart Gear/Watch (to display text alerts, control calls) and a Bluetooth headset. I need all the three to communicate with my mobile phone at the same given instant.
Is it possible to achieve the same ?
What are the challenges involved if I need to develop an application on my own if I had to achieve the above possibilities ?
Your help is highly appreciated.
Note:
- BLE has star-based network topology and maximum devices per Piconet is 8 including the Master
- Please help me in understanding/visualizing the above theory that I learnt.
Thanks.
The Bluetooth Classic has a limitation of 7 slave devices in a piconet and they are time and hop synchronized to the master ( ie master and slaves share a common physical channel and it is not possible to address more than seven slaves for a master when in Active mode).
In BLE each connection from a master to a slave operates in an independent physical channel( ie LE slaves does not share a common physical channel with the master), hence there is no limitation imposed by the Specification except as specified by the Connection interval and slave latency rules ( Note that individual bluetooth controller manufacturers may decide to limit the number of connections depending on the practical bandwidth limitation).
please see the Bluetooth Classic vs Bluetooth Low energy Topology below.
Is it possible to achieve the multiple sensors ( BLE) and Headset (BT classic) connected to mobile?
Yes it is very much possible, except that there are some BT4.0 controllers which doesn't allow LE advertisement while connected to another BLE device. please check the known limitations in a particular bluetooth controller.
It's the Bluetooth controller that has the limitation. Different Bluetooth controllers have different maximum number of concurrent connections. It's usually between 5 and 14. However Android has an additional hardcoded limit of 10 for some strange reason.
Other than this, there shouldn't be any particular challenges.
Related
I am pretty new to IoT and BLE. What I want to achieve is to write on GATT characteristic of at least 100 peripheral devices simultaneously or in a very short period of time(i.e. less than 100ms). Currently my peripherals are Ble nano (nRF51822) with custom GATT service running on them. I am using my Mac as central BLE. I am using Node.js and noble to implement the central. I want to know if such thing is possible at all and if possible, please link me to an example code. :)
You should note that Bluetooth chips for computers are usually (quite arbitrarily) limited to only a few simultaneous connections. Common values are between 3 and 14. Even if you connect a few at a time, send the characteristic value, disconnect and then connect next devices it would be impossible to do this within 100 ms. If you want to send the same data to everyone you should instead let your computer advertise and the nrf devices scan. That way you broadcast the data instead.
I couldn't find a clear explanation what is Bluetooth le multi advertising.
For example, in Specification of the Bluetooth System, I see only
description of BLE advertising but not multi advertising.
What the difference between BLE advertising and multi advertising?
Thanks
LE Multi advertising refers to a specific offload (non bluetooth specification) feature that has been implemented in the Android releases by Google, starting from the L release.
What multi advertising means is, that your Android phone or a device with Android stack, can enable multiple advertisement trains at the same time. For instance, one specific app can set certain advertisement data (example supported services etc.), advertisement parameters and enable advertisement, and so can N number of other apps, on the same device.
At the hardware level (or physical layer), these advertisement trains are interleaved between the three advertisement channels (37, 38, 39) and thus your phone behaves as multiple peripheral devices at the same time. All these advertisement trains also have a separate Random private address, so they are seen distinctly by the remote scanner.
Bluetooth Smart has two ways of communicating. The first one is using advertisements, where a BLE peripheral device broadcasts packets to every device around it. The receiving device can then act on this information or connect to receive more information. The second way to communicate is to receive packets using a connection, where both the peripheral and central send packets. We will focus on advertisement for several reasons:
You can’t create a connection between two devices without using advertisements. Defining the data and format of advertisement packets is usually the first thing you work on when developing a BLE device.
A large number of BLE products sleep most of the time, waking up only to advertise and connect when needed. This means advertisements have a big impact on power consumption.
Users want responsive products, and the advertising interval is critical in quick connections.
Advertising is by design unidirectional. A Central device can’t send any data to the Peripheral device without a connection. But a single peripheral can advertise to multiple masters in the area.
ref:http://www.argenox.com/bluetooth-low-energy-ble-v4-0-development/library/a-ble-advertising-primer/
Can Two Bluetooth LE (4.0) Devices talk to each other ?
A good example can be if two FitBit devices talk to each other .Just pass basic information ?
or One Coin Device communicate each to other ? (https://onlycoin.com/)
As of today we see most BLE Devices like fitbit communicate back to Iphone/Android Only .
Wont it be possible to have both FitBit deices communicate each other ?
I am thinking of creating a "Card 1: Bluetooth Card(LE 4.0)" which when Contacted with another "Card 2: Bluetooth Card(LE 4.0)" can exchange some date . After the exchange Card 1 will send the data it got from Card 2 to an IOS /Android device and the same applies to Card 2 . Is this possible at all ?
What you want to achieve is currently not doable. Bluetooth Low Energy (v4.0) only allows the star topology configuration, i.e. Only one master and multiple slaves; the master can talk to the slaves at the same time but the slaves cannot talk to each other. According to the Bluetooth website, they state:
"Bluetooth low energy technology uses a 32 bit access address on every packet for each slave, allowing billions of devices to be connected. The technology is optimized for one-to-one connections while allowing one-to-many connections using a star topology. With the use of quick connections and disconnections, data can move in a mesh-like topology without the complexities of maintaining a mesh network".
One way to achieve what you want is to switch roles between transmissions (i.e. the device that was once a slave then becomes a master) but this will be very complicated and many BLE chips do not support this feature.
I hope that this helps.
This is my first question in Stackoverflow :)
I'm trying to make few modifications to the Ti Sensortag but I have few questions please:
1- is it possible to make the sensortags communicate with each-other without a gateway?
(lets Say I put Sensor1 in bedroom 1 and sensor 2 in bedroom 2 can I make them exchange readings without the need for a gateway?)
2- can I install a micro USB over the interface connector to be able to use a portable battery pack? (photo of the interface connector)
thanks
You'll get better more in depth responses on the TI support forums as Ifor has said.
However, I can tell you the answer to #1... Regular bluetooth allows for things like piconets, but Low Energy does not. With LE you have a client/server (master/slave) connection between two devices only. It may be possible to modify the firmware on the sensortags to allow them to make connections to other sensortags, but then they'd have to give up whatever connection they currently had to do so. The master devices can connect to multiple slave devices, but the slave device can only be connected to one master.
As the sensortags are currently designed, I think they only work as a slave (server) device.
Press releases say that the new 4.1 spec allows for a single BLE device to act in both roles--central and peripheral eliminating the need for a gateway. A 4.1 update is, in theory, possible with 4.0 radio hardware like the SensorTag has. I personally haven't seen an example of this however and SensorTag processing resources may be a limiting factor to a dual role.
The Battery Pack connector breaks out VDD_EXT and GND and the SensorTag hardware schematic is available. Analysis by a hardware design engineer should be able to determine the suitability of a USB source powering option.
http://processors.wiki.ti.com/index.php/SensorTag_User_Guide
Is it possible to implement Bluetooth devices to provide conference rather than one-to-one operation.
Are there any development toolkits that will allow me to configure BT devices in this way, or modifications that can be done to the BT stack or an add-on protocol.
I need to configure several Bluetooth adaptors to simultaneously communicate with one another. I think BT allows up to 10 'pico-nets' but I need specialiced advice.
I would welcome any links to resources, or replies from Bluetooth experts.
Thanks in anticipation.
I've heard of something close to this, called a piconet. Googling "bluetooth piconet" should point you in the right direction.
A master device can be networked in this way with up to 255 slave devices, but only 7 can be active at any one time. This is more of a one-to-many communication than many-to-many, but could potentially be approximated by having the master device act like a network switch.
Update: I just read that slaves in one piconet can participate in another piconet as either a master or slave, forming a "scatternet".