I would like my BLE device (running on Linux) to be a broadcaster (broadcast data) - no connection is to be allowed. Following are the questions I have:
Which BLE profile would be most suitable for this requirement?
I understand that GATT is mandatory - does it mean I should use GATT and advertise my data in beacon and disallow any connection?
I have seen that Windows doesn't scan a BLE device which is simply a broadcaster i.e doesn't allow connection. Why so and what should I do for Windows to detect my broadcaster device?
Regards
Related
My current understanding of the BLE gap role "broadcast" is that it broadcasts data packets with no option to connect to that device.
My question is therefore: is it possible to combine the gap broadcaster with a gatt server that contains a writable characteristic, so that gatt clients still have the option to write to the gatt server?
Yes, you can combine the Broadcaster role with the Peripheral role, to achieve what you want.
As stated in the title, can both be ran simultaneously or is a second adapter required? For example, can one adapter run both BLE and BT classic at the same time - the BLE beacon broadcasts the MAC for opportunistic clients to connect to using RFCOMM.
If you are using a common CSR 4.0 Dongle or Ampac AP6212 (which purportedly uses the same Broadcom chip as the RPI3) then this is possible - they are "dual-stack".
Given this, the typical USB CSR chips have a hard limit of two connected RFCOMM clients and the Ampac, 8 or maybe more (tested for sure 8).
Is it possible to make a peripheral scan for advertisments while connected to a central? It seems like it is either scanning for advertisments or have your peripheral connected but I need to do both. The peripheral should be able to report RSSI measurements from advertisements it picks up.
I'm using 'bleno' for the peripheral and 'noble' for the scanning on a linux box (bluez)
The answer to this differs depending on the version of Bluetooth that your device is on.
For Bluetooth v4.0:
A peripheral cannot scan at all, whether in a connection or not. The peripheral can only send out adverts or accept incoming connections. For more information you can have a look at this document, page 18:-
http://chapters.comsoc.org/vancouver/BTLER3.pdf
For Bluetooth v4.1 onwards:
A device can be in central and peripheral role at the same time. By implication, this means that if a peripheral is connected to a central device, it can still scan for devices in it's "central mode". More information can be found in this link, page 5:-
http://www.ietf.org/proceedings/89/slides/slides-89-6lo-4.pdf
So in conclusion, if your device is BT v4.1 or newer, then this is dependant on the chip manufacturer, and if it is v4.0, then no, because the Bluetooth specification does not allow it.
I have been asked to figure out how to achieve bluetooth communication through an off-the-shelf dongle (in this case a dongle utilizing the Broadcom BCM2045 chip) using the FTDI Vinculum 2 (VNC2) USB controller. I have custom firmware written for the VNC2 to communicate with a generic USB device with the VNC2 acting as the host, and I can successfully read the VID and PID from the dongle as well as the USB device class, subclass, and protocol. I can also send data to the dongle using the bulk data endpoint and I believe the device is receiving though I have no way to tell at the moment.
So I believe I can communicate with the dongle, the problem is I have no idea WHAT to communicate to it in order to set it up in discoverable mode or to pair it with another discoverable device, nor how to actually transmit data through the wireless link once it is paired. I don't even know if there exists a standard communication protocol for this type of thing or if every device will be different. I have a vague understanding of the bluetooth protocol stack and it is my understanding that I won't be required to fully understand that as it should be implemented in the dongle on one end and in the android smartphone that we hope to connect to on the other end. Like I said, I can currently send data to the bulk endpoint, is it true that this endpoint is only for data transfer over the wireless link and I will need to connect to a different endpoint in order to send setup/configuration messages to the dongle?
In short, I need to know what data to send over the USB bus to control any generic bluetooth dongle if possible or at least one specific bluetooth dongle. I have a USB port sniffer but the complexity of the output while using the dongle to communicate is staggering and I doubt I'll ever figure it out.
Thank you in advance.
Bluetooth dongles communicate with host software stack using HCI (host control interface), which is defined in the Bluetooth spec. For reference, you can look at source code for the open source BlueZ stack (standard linux stack). You could run BlueZ on linux talking to your USB dongle, and use hcidump to capture actual packets going across HCI. You can also check out hcitool and hciconfig for performing specific actions.
Can a WindowsCE device connect so more than one BlueTooth device? The device needs to both serve as a BlueTooth hands-free speaker for a phone and connect to a third device via a serial BlueTooth connection.
Can an application do this without the need of a speciel driver?
You must understand that Windows CE is a modular OS and any specific platform capabilities are implemented by an OEM. An OEM can create a Windows CE device with absolutely no Bluetooth support or they might choose to implement just a Bluetooth client profile (say as a bluetooth audio device) or they may choose to implement a Bluetooth server so they can consume a Bluetooth serial device. They may also choose to implement both. Beyond what the OEM does in software, the hardware itself might allow only one or the other (or both or neither for that matter).
The short of this is that we can't actually answer your question becasue there is no generic answer that fits all devices. You have to ask the Device OEM what they support and if they can extend that support if they don't support what you need.