Develop Reference

Bluetooth BLE Implementation

I'm trying to implement a Bluetooth (BLE) gateway into a project to transfer data between hardware and a mobile device with an application. The hardware is not unique, it could be mass produced with the controller having the same program flashed into it.
If 100 of the hardware product is made, powered up sitting side by side, what is the best way to set up the information that the BLE broadcasts to advertise so that it can be received by a mobile device, and only 1 hardware and mobile device can be connected at any time.
For example, if you have 3 of the same fitness tracking watches side by side, and you only want to connect to 1 of them, how do you distinguish which is which on say the phones bluetooth pairing menu.
Does each of the manufactured hardware need to have a unique ID that shows on the mobile device (eg ABC11, ABC112, ABC113 etc), and how do you program 100 unique programs into the hardware quickly.
On the other hand, should each of the hardware have the same ID broadcast, and then the user just hopes for the best if the correct hardware is paired.
(BTW, the hardware is an arduino based microcontroller using a BM70 BLE module. neither of which are intended to be modified by the user)
Assistance appreciated.
Thanks. Nunya

You do not have to manually program a different MAC addresses for each device, the BM70 module is the one that provides the BLE MAC address and they are supposed to have unique ones. Sometimes manufacturer recycle (reuse) the addresses, but I think the chance to hit a MAC twice with 100 devies is pretty low.
If your devices are all the same and use the same program they all offer and advertise the same BLE service. The service and containing characteristics are the feature that distinguishes your devices from other BLE devices. A true BLE device that does not also use Bluetooth Classic will not show up in your phones bluetooth settings or pairing menu. BLE requires a dedicated app where you scan for BLE devices and idealy filter for the special service you are using to only find your own devices.
To distinguish between 100 devices placed next to each other (if this even matters since they are all the same) you need to either read the MAC address and prit it on a label for each device or use some status LEDs to show the connection status on your arduino. If you connect to one device the LEDs could start blinking to show which device you are connected to.

Bluetooth proximity scan while paired

I have been doing a ton of research on this project I want to do, probably read every SO post (bluejacking, RFCOMM, beacons, etc...) and my head is spinning.
I want to create a system at home, using Arduino (with bluetooth le) that will scan bluetooth and detect when my phone or any of my family members phones are in proximity. Whether this is a MAC scanner or simply getting the friendly name. I would also like to get the RSSI. I dont need to do accurate distance measurement but I would like to know approximately how close they are. Does anybody have any suggestions for this approach? I know I can create an app on the phone and have it become a beacon and this may be an option but I am concerned with Android, it would have to be Marshmallow 5.0 at a minimum. I would like support to be a little lower than that, like JB or KK. So, it seems like there should be a simple scan, just looking for the MAC or name. That is all I really need.
That said, the main question I have is, can you scan for and see bluetooth devices in range if they are already paired to something? Like a Bluetooth headset? I understand bluetooth is point to point but does it allow multiple connections or at least broadcast the mac or name when paired?
This question, along with any general suggestions will help me out tremendously!
Thanks!

Bluetooth Discovery from the Listener involves Listening for Bluetooth Inquiry packets(RX) and inquiry response (TX).if done continuously this will deplete the battery. Hence most devices (including Mobile Phones and Headsets) has a policy of when to be discover-able and connectable. Headsets in particular are discoverable only when they are instructed and connectable until one device is connected to it ( There are probably exceptions where the headset has the capability to be connected to multiple phones at the same time). Most Mobile Phones are discoverable only when they are in settings screen ( Android,IOS and Windows Phones), but unlike the headset case they are connectable.
so one option with the MobilePhone is to see if it is possible to connect to them after pairing once ( for example by trying a service search on the remote device and see if it returns the service attributes, this internally makes a connection and indirectly ensures the presence of the device).
if you are specific about a mobile phone which is already paired then you might need to establish a higherlayer connection ( such as SPP) with Authentication and encryption. This would force a two way check between devices to see whether they are already paired. other less secure option is to rely on the Phone (Android and IOS phones doesn't generally Allow a higher layer connection without encryption/pairing) and try to establish an SPP connection to the phone.
Another option is to use Bluetooth-LowEnergy. But Note that security in BT was superior to BLE till BTv4.1 and same on BTv4.2.

Is it possible to scan for all the WiFi enabled android devices, not just hotspots?

i have been trying to develop to an app that scans for nearby WiFi devices. I found lots of similar apps in the market, but they scan only for nearby hotspots(access points). Is it possible to scan and find devices that have just turned WiFi alone ON.
If so please say me how to (the code snippet) .. thanks in advance ..

There are 2 parts to the answer.
Most WiFi devices can operate in AP mode (if proper software installed) and in this case they will appear as a normal AP to anyone scanning around.
If you want to find other WiFi devices that aren't in AP mode you'll need to switch your device to promiscuous (sniffer) mode. This needs to be supported by your device driver/firmware. Operation in sniffer mode causes the device to indicate all packets in the air, including those that aren't addressed to you. If your device supports this op mode, you'll need to instruct it by sending relevant command(s) - that's a proprietary interface that varies per device SW vendor.

These nearby devices must send some signal, which your device can receive in order to detect them. Normally they dont do that I think. But if you can install an app on the other devices, this app could send a broadcast signal, which your device can pick up.
If there is no standard signal, for which you can listen, it becomes difficult. You have to build some kind of network sniffer.

A sniffer is the process of reading a direct port, in this case the listening port wifi. Read a port means pointing to a specified address and read the same buffer. This process is at low level, you must do it in pure C and compile in NDK. If you know of these issues is complicated.

How to send Bluetooth data to an unknown device?

I'm asking because I've been facing that issue for weeks.
I need to develop an Android application that can be able to perform an Bluetooth Connection and send data to an Bluetooth Hardware.
Ok, so here's the point:
is it possible to perform a RFCOMM connection to an 'unknown' device?
I mean, is it possible to do this without having any information about the hardware code?
Because i'm only able to modify the AndroidDevice (cellphone) code, for SENDING purposes.
I want to send a byte and make sure it was received, but there's only a sending code.

Could we have some more details? Is the other device accessible by you, as in can the other device know information about the Android device? And what do you mean by a "sending code"?
The Android device can pick up any active Bluetooth device in its range, and know the name and address of those devices. So, if the Android device doesn't know anything about the Bluetooth device it wants to connect to, you can always sort through the list of devices in range, and get its hardware code through that.
See the documentation about Bluetooth, specifically the Finding Devices section:
http://developer.android.com/guide/topics/connectivity/bluetooth.html
I've done a fair amount of Bluetooth work with Android devices and Arduinos, and the Bluetooth library might be a bit of a pain to work with, but it is powerful.

With bluetooth the two devices have a UUID. If you a writing a program that runs on both devices you have them listen for that UUID. When they connect as a client or a server you have a dataInputStream and a dataOutputStream. Then you can push and pull bytes out of those.

How to pair and connect to a headset

How can I connect and disconnect to/from a headset bluetooth device programmatically?
The application should work for Android 2.1+
In other words: I have a headeset. I can pair, connect, disconnect to it using Settings/Wireless and Networks/Blutooth Settings.
But how can I do all those things (pair, connect, disconnect) from my program?

Please chech this link.
The android bluetooth example (already listed) has a bunch of issues (not the least of which is you need 2 android devices to get it to function).
Take a look at the example at http://luugiathuy.com/2011/02/android-java-bluetooth/ where he is using bt on the android device to hit a server (to do some robotics work).
Be aware of UUID issues (the way that BT decides what connection it can make is defined in the UUID), and check out http://www.avetana-gmbh.de/avetana-gmbh/produkte/doc/javax/bluetooth/UUID.html
Keep in mind that the 16 bits represented in the UUID (ie, 0x1101 for Serial Port) is misleading in that its really the least significant part and needs to be coded 0x00001101.