I was reading the Bluetooth LE primer document and stumbled across the table given below:
My doubt is how can receiver be optional if the observer's only job is to receive BLE data and not transmit any thing back. Should it not be the other way? Transmitter being optional and Receiver being mandatory?
P.S. I understand that in hardware BLE radio implements both Tx and Rx and its left upto the application to use either or both.
I am just reading the BLE specification document and have not implemented anything yet however this observer device definition did not make sense to me. I expected observer to have a Rx mandatory and Tx optional.
I believe this is a mistake or a copy/paste error in the document. If you have a look in the official Bluetooth specification you'll find the correct description (Bluetooth Core Specification v5.3, Vol 3, Part C, Section 2.2.2.2):
Related
I'm dealing with the following challenge. In my system, there are two devices. Tags and anchors. Tags have BLE module with the transmit power 0dBm and not Long Range feature (BLE 4.0). Anchors have BLE module with transmit power over 8dBm and Long range feature (BLE 5.0).
I want tags to only receive some commands. Bi-directional communication is not necessary. This way, I can utilize the transmit power of anchor (8dBm) and thus quite bigger range, if tag with 0dBm is only receiving.
I read something about Observer/Broadcaster principle, where connecting is not necessary. But somehow devices have to agree on what frequencies should they hop on, the step and so on.
I'm asking, is it possible for device to only receive commands without previous negotiation with the sender?
Thank you very much for help. I'm beginning with BLE standard and there is a lot to learn.
Yes, it is possible to send data via adverts/scanning only. This way, there's no connection that needs to be established, and therefore no connection parameter negotiation takes place. As for the frequency hopping agreement - this happens via the baseband (in other words you will not deal with this in the software yourself) and is generally not applicable for advertising/scanning (these happen on 3 frequency channels only and therefore it is likely that the observer will catch what the broadcaster is broadcasting).
However, keep in mind that because you are broadcasting/advertising the data as opposed to directly sending it, that data can be received by any observing/scanning BLE devices which is not desired for safety/security/privacy purposes.
For more information on BLE communication, I recommend the links below:-
Getting Started with Bluetooth Low Energy
Is it Possible to Send Data with BLE Broadcast Mode
I am currently working on a project which aim to detect Bluetooth and decode Bluetooth packets (I use a Hack RF One to make the detection). I have made a Gnuradio Flowgraph in order to demodulate Bluetooth signal and I am trying to decode visualy the packets by searching a Bluetooth frame on a binary file.
Unfortunately, I didn't succeed to recover a clear view of the Bluetooth signal. To be precise, I am pretty sure that I detect Bluetooth on my sinks but when sending this to a Clock Recovery + Binary Slicer blocks, I am unable to recover interresting data in the binary file (especially the MAC adress of the sending device, which is part of the a Bluetooth packet). Moreover, I would like to know what type of network layer (physical, transport, baseband...) is intercepted in this type of process. In my case, I aim to intercept baseband layer packets.
Additionaly, I am interrested in knowing how to use the gr-bluetooth because I can't find a lot of documentation concerning this block. I think this can be interresting for the development of my project.
Could you please, give me your view, opinion about this problem ? I am stucked at this stage without knowing the exact origin of my issue. (Here is my flowgraph GnuRadio_Flowgraph and a screenshot of one of my Bluetooth detection Detected signal at 2.402GHz).
Thank you very much,
You probably need an ubertooth instead https://www.sparkfun.com/products/10573
I read that the bluetooth frequency skipping is spread wider than the HackRF can read, so at-best, you're going to miss 75% of frames if you only have one hackrf connected.
I bought a HM-15 BLE bluetooth module and successefully connected to Arduino. I am able to sent At commands and I would like to use it for scanning for iBeacons and get their major and minor.
Using AT+DISC? I can see the beacon address but I cannot connect to it and now I am stuck on how to retrieve major and minor
Can you help me? Here is the datasheet of the module:
http://www.elecrow.com/download/bluetooth40_en.pdf
Thanks
Bluetooth beacons do not require a connection and you read the identifiers directly from the advertisement.
Read section 19, Start a discovery scan, and learn how to read and decode the bytes in the discovered peripherals. The exact byte layout varies for different beacon types. For AltBeacon, an open source beacon variant, you can see the byte layout here: https://github.com/AltBeacon/spec
To decode a proprietary beacon format, you will need to learn how that beacon layout differs from the example linked above.
Old question, but just for the record, you can use AT-DISI?
This will scan for beacons, including iBeacons and also AltBeacons. The response from HM-10 will include RSSI for each.
PS: I'm assuming HM-15 and HM-10 operate the same way. Probably not exactly a fully reasonable assumption.
Bluetooth standard V4.0 [vol. 2, 7.7.65.2] allows the controller to "queue advertising reports and send information from multiple devices in one LE Advertising Report event".
To manage this feature, the HCI protocol includes, among the Event parameters, the field Num_Reports (with values between 1 and 25).
In case Num_reports is > 1, how the Event parameters are organized in the event packet received through HCI?
Note 1: The Bluetooth standard seems to specify an unusual ordering of the data, not packing each advertising report after the other (as suggested by the event description), but packing instead each type of information after the other (i.e. all Event_types for each advertiser, followed by all Address types, then all addresses, and so on till last field, with all rssi values). Do I understand well?
Note 2: I didn't find any software example managing more than 1 advertising report in one single event. Does it mean that this feature of the standard isn't used by real-world devices?
You understand correctly.
When there are more (Num_Reports > 1) advertising reports packed into one event, these parameters are contained by the event:
Subevent_Code,
Num_Reports,
Event_Type[i],
Address_Type[i],
Address[i],
Length[i],
Data[i],
RSSI[i]
So for example if Num_Reports = 3, then follow 3 Event_Type (each being one of ADV_IND, ADV_DIRECT_IND etc.) for the 3 reports, in the order they were received.
The same order is preserved for all other parameters marked with [i].
To answer your second question: the standard says the controller may queue more reports into one event. Perhaps the implementations you have looked into don't do it.
I am trying to figure out how the FORA d15b blood pressure monitoring system communicates via Bluetooth. I want to be able to eventually write an Android app that can receive blood pressure data from the device.
More specifically, I want to know the exact data to send to the device in order to request blood pressure information. I also want to know the data that the device sends out. However, I don't even know the format of the data being sent/received.
I know that FORA has a PC app that can communicate with the d15b device via Bluetooth but I don't know what information its sending/receiving over Bluetooth, and that's what I want to know.
Here is Bluetooth information I know about the d15b device:
Bluetooth Carrier Frequency: 2400MHz to 2483.5MHz
Bluetooth Modulation Method: GFSK, 1Mbps, 0.5BT Gaussian
Transmission Power: +3dBm to –20dBm; Power control 4 stage
Receiving Signal Range: -88dBm to -20 dBm
Receiver IF Frequency: 1.5MHz center frequency
Maximum Data Rate: Asynchronous:723.2kbps/57.6kbps;
Synchronous: 433.9kbps/433.9kbps
I'm struggling to even find a starting point. Any help is appreciated! Thanks in advance.
I am familiar with C, Java, and Arduino if that helps at all...
NOTE:
Unfortunately, I am new to Bluetooth. After doing some research, I am still pretty clueless on how to solve this problem. In the title, I say unknown Bluetooth device because I just want to be able to read what I/O of an unknown Bluetooth device, which in my case happens to be the d15b that I know nothing about. Sorry if the question has been addressed already or if this is an inappropriate place to post this question. I wasn't sure.
Bluetooth data is encrypted. So it's not possible to hack it easily.
Forget it.