I have an android phone and I want it to communicate with 10 bluetooth modules, not simultaneously. I know that a master device can have 7 slaves for bluetooth connection. does it mean "pairing"?
The question is can I have my phone paired with 10 bluetooth devices? Then send them data seperately?
There is no set limit on the number of pairings possible for a device, except for any limitations made by the platform or bluetooth software stack (eg. limited storage).
does it mean "pairing"?
Bluetooth pairing and connecting are two separate operations.
When two Bluetooth devices pair, they will exchange Bluetooth addresses and encryption keys. If pairing is successful, it allows the devices to connect to each other at a later time.
When two bluetooth devices connect, the profiles are established (a2dp if a speaker, hfp if headset, etc), and they can communicate.
Sometimes there is confusion between pairing and connecting since most smartphones automatically connect after detecting a successful pairing.
Pairing is just done once, typically when you buy a Bluetooth product. Connection is done whenever you use the product.
The question is can I have my phone paired with 10 bluetooth devices?
Then send them data seperately?
As mentioned in the other answer, the maximum number of paired devices is platform dependent, it varies from product to product, but there is no set limit. The maximum number of connected devices (that you could send/receive data concurrently to) is 7 according to the Bluetooth specification.
Related
We have multiple devices (same kind) advertising at the same time. But in iOS, all the advertising packets are treated as one device.
Understand the reason: iOS filtered out the BLE address for privacy reasons.
Without BLE address the advertising packets from the difference devices are exactly the same.
My question is: is it possible to use iOS core bluetooth to tell there are multiple devices are advertising?
Thanks
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 am new to developing a mobile app with bluetooth connection to peripheral device. I searched that GATT is the relevant profile used for bluetoothLE communication but our client recommended that we use UART service. Now I am confused as to
1. how these two things are related and
2. Do we have to opt for one of these, if so, what are the pros and cons of each. Thanks
Legacy Bluetooth provides the serial port profile (SPP) - This is essentially a serial input/output stream over Bluetooth.
Bluetooth Low Energy provides a number of profiles, but the most commonly used is GATT. GATT exposes characteristics/attributes which are a little like variables that you can read from/write to. A read/write is limited to 20 bytes.
Many embedded BLE chipsets provide a "UART emulation" over BLE GATT. Here a pair of attributes are used; one for read and one for write.
The Central device writes bytes to the 'write' attribute and the embedded chip sends them out of a serial port on the chip.
Similarly, data that is written to the chip's serial port and sent to the central via a notification of new data in the 'read' attribute.
You don't say what platform your are developing on, but one important consideration is that use of SPP on iOS requires your hardware to be MFi certified by Apple, while BLE/GATT does not.
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.