Can an Android device pretend and connect as a Bluetooth controller?
Can Android devices connect as a device to, say, a PC and act as a gamepad or similar device?
Is it allowed and doable in code without root access?
I tried this code: Connect Bluetooth devices. But it can not get it to pair.
Short answer, yes.
I recommend looking at Google's example project on Bluetooth communication BlueToothChat initially. Based on what you've written, I think you're missing several important steps.
You need all of the following components / steps:
General Overview
Set up Bluetooth
Set Permissions
Scan for other Bluetooth devices
Query the local Bluetooth adapter for paired Bluetooth devices
Connect to a remote device as client or server
Transfer data over Bluetooth
If you have access to the device your attempting work with as a controller, then you can create your own communication setup. Define a set of parameters to write and read on both sides that emulate the functionality you're looking for.
If you do not have access to creating your own read/write setup, or you want to use standard interaction methods for the industry, then the best bet is the Bluetooth HID Device profile mentioned by #Morrison Chang.
The HID profile basically establish an industry standard of required device features, read/write formats, combinations of features equaling a controller type (ie: "this is a keyboard"), and data mappings for what read/write numbers mean on either side of the client / server connection.
From the linked comment thread, the Kontroller project on Github has source available for your peruse.
There's also a reasonable Intro to Bluetooth HID that covers some of the topics on what Bluetooth HID is actually doing.
Finally, also recommend looking at Google's own BluetoothHidDevice page.
Related
I would have to build two apps (Android and iOS) and control some equipment via Bluetooth. For clarification, i cannot just use OS device discovery to connect to the equipment because there's hundreds of them and their position is very important (as well as the user's position when issuing commands), thus it's less of a hassle for operators to just point the phone's camera at a QR code and connect than having to go through a long list of devices with mangled names.
I haven't found many details about specifically using a QR code for bluetooth connections, but i figured that people experienced with this kind of communication will be able to say if it can be done. Please correct me if i'm wrong, but my understanding is that a bluetooth socket is not that different from a TCP one and a connection could be established by knowing the server's credentials.
Can I use a QR code to store device credentials that I can use to establish a connection? It doesn't really matter how much information needs storing, the QR code can contain any sensitive information.
Is there anything more, apart from the UUID, that would need storing on the QR code?
Is it simpler to configure the device as a server and the phone as a client for this specific request? There will be multiple operators that will need to work with these devices.
This is specific to Android and iOS, but if the points above were possible, would I get an OS pop-up window for each connection? Would skipping the discovery step save the operator the hassle of having to confirm the connection to the OS?
If the target device is configured as a server, each with its UUID as the QR code, can i scan that code and open a socket to that very device without manually connecting to it from the phone's menu?
Background
I have an idea for an app on vacation that needs to communicate to other phones with the same app. While on vacation those phones might not all have internet as roaming can be very expensive. The data is not a lot: like 500 kB max would suffice (in json).
Every phone has a bit of info that all the other phones would like to know, but if it helps the info can be stored on 1 phone (master phone from now on) and shared later to the other phones when back home over internet.
Phones
Android, iPhone and Windows Phone
We can't assume they have NFC, IR or zigbee. Just the hardware almost every phone has like bluetooth, camera, microphone etc.
My ideas
QR codes that changes, based on new info: If the first phone is scanned the second phones QR code has data from the 1st phone and itself and the 3rd phone has data from the 1st, 2nd and 3rd (itself) until it reaches that master phone that holds all data.
Data transmission trough sound that we can't hear (or we can). Con is that I don't know if something like this exists for mobile platforms and writing it is like a 3 year master thesis project.
http://nearbytes.com
https://applidium.com
https://developer.chirp.io/
Bluetooth. Can we connect like 8 devices? Would it work consistent (connecting even my headphones can be a hassle, what about 8 phones who try to connect simultaneously)
All of these ideas have big cons. Maybe I'm overlooking a better way.
I will add a bounty to the question for the best solution
An answer that explains it with a little bit of code reference (link is ok) is always better than just: "use bluetooth man"
TL;DR
The easiest (and most supported) way of getting multiple devices to connect to each other is using WiFi. Since your goal is to achieve data transfer with no internet, the most appealing solution would be to use a Peer-to-Peer network structure.
The two major smartphone OS's (Android and iOS) have API's and documentation on creating and transferring data over a Peer-to-Peer network.
Android WiFi P2P
Apple Multipeer Connectivity
These two also have a means to encrypt the data being transferred.
Windows doesn't seem to have an API to allow multiple peers connected, but their Proximity Class will work for one device at a time.
I can give a few outlines over the different options in each major OS:
Android
Android's WiFi P2P (peer-to-peer) API was created for transferring data without internet or another network.
From their documentation:
The Wi-Fi peer-to-peer (P2P) APIs allow applications to connect to nearby devices without needing to connect to a network or hotspot (Android's Wi-Fi P2P framework complies with the Wi-Fi Direct™ certification program). Wi-Fi P2P allows your application to quickly find and interact with nearby devices, at a range beyond the capabilities of Bluetooth.
Google even has Documentation and training on this API.
iOS
Apple's Multipeer Connectivity.
Very similar to Android's P2P API, they claim:
The Multipeer Connectivity framework provides support for discovering services provided by nearby iOS devices using infrastructure Wi-Fi networks, peer-to-peer Wi-Fi, and Bluetooth personal area networks and subsequently communicating with those services by sending message-based data, streaming data, and resources (such as files).
Here is a decent looking tutorial on using Multipeer Connectivity.
--EDIT--
Another iOS way of doing this, which is a bit of a mis-utilization(?) of the tool, is by using GameKit.
However, I think that to get it to work for your purposes might result in a bit of a hack, since the "players" have to be using Game Center.
Windows
The only way (apparently) to connect phones in Windows Phone, is by using Proximity, however, that only gives you the option of connecting no more than two phones together.
They state:
Proximity is a great way to create a shared app experience between two instances of your app running on two different devices.
Those are options in each of the major mobile device OS's.
App usage could be something like:
Decide which device was going to be the "master", so that other devices can connect to it. It isn't required to know this before deploying the app, but there should be a way for the user to decide whether he is going to be a client (receiving data) or the server (pushing data).
Once it was decided between the group of devices which was going to be pushing data, that device would have to be registered as the server (in the Android P2P API, you can establish a "group owner"), and then start looking for peers by initializing the service.
Then, once the devices are connected to the master device, you can start pushing data. An additional bonus is that when using Android WiFi P2P, all communication is encrypted with WPA2, and with iOS, you can enable encryption using MCEnableEncryption (however they state that is slows down data transfer rate).
Now you would just have to pick one method to go with, and make sure that all the phones ran that OS. Because these three methods of connectivity won't work together.
All of the three methods listed are done programmatically, so there should be no strange or odd things that your user will have to do. Searching for other devices, connecting, and transferring data can all be done within your app.
More help can be provided if the question is narrowed down to specific problems, but this should be enough data to get you started.
Don't try QR or sound. I think it would be very painful to transmit 500kb of data.
Bluetooth seems like a good solution but maybe, as you already said, hard to configure.
What do you think about wifi?
At least every Android and iPhone device can create a mobile wifi hotspot. By using this, you can easily setup a environment where 8 devices are in the same LAN (without using the internet by any of your devices).
Now your "master phone" runs a simple server to synchronize data (just like an internet server would do). Every of the seven clients could receive the ip adress of you master by scanning a simple QR code or sending a short message and afterwards configure itself accordingly.
Have you checked Alljoyn?
As quoted:
"Developers can write applications for interoperability regardless of transport layer, manufacturer, and without the need for Internet access"
You can create a Wifi connection between your devices. Than after connection it creates local network between your devices. Inside this network you, of course, can interact between your devices using TCP/IP connection. It works both on Android and iOS. Simply lauch your app as server on the one device
EDIT
Note, you have to connect your devices using any network. It is possible to connect the devices by initializing your device as WiFi-router. It can be both Android and iOS. If it is possible, you can connect your devices to any wifi connection.
Than, launch your app as Server-socket, the others as clients.
for Android (java) server use this link:
https://docs.oracle.com/javase/tutorial/networking/sockets/clientServer.html
try (
ServerSocket serverSocket = new ServerSocket(portNumber);
Socket clientSocket = serverSocket.accept();
PrintWriter out =
new PrintWriter(clientSocket.getOutputStream(), true);
BufferedReader in = new BufferedReader(
new InputStreamReader(clientSocket.getInputStream()));
) {
for android device client:
try (
Socket kkSocket = new Socket(hostName, portNumber);
PrintWriter out = new PrintWriter(kkSocket.getOutputStream(), true);
BufferedReader in = new BufferedReader(
new InputStreamReader(kkSocket.getInputStream()));
)
The same idea is for iOS (Objective-C):
server
https://developer.apple.com/library/ios/documentation/NetworkingInternet/Conceptual/NetworkingTopics/Articles/UsingSocketsandSocketStreams.html#//apple_ref/doc/uid/CH73-SW8
and client:
https://developer.apple.com/library/ios/documentation/NetworkingInternet/Conceptual/NetworkingTopics/Articles/UsingSocketsandSocketStreams.html#//apple_ref/doc/uid/CH73-SW4
A better way could be use Ble.
It's easiers to connect the phones because you don't need user confirmation.
Seems like you can connect up to 20 devices Maximum number of peripherals on CoreBluetooth?.
To transfer 500KB should require few minutes (may be between 2 and 5).
You can track an Android device without Internet via GPS.
Connection without The Internet:
SMS
USSD
DTMF (very slow)
How to design a tracking device on USSD is mentioned at
M2M IoT Cookbook
How to develop a device based on Wireless Wide Area Network modules
You also can use the Android phone as a data logger and store under the Micro SD Card and read the card by:
Replacing the SD card to your PC
Streaming the data local by Bluetooth
Forwarding the data at home by Wi-Fi
Or Possibly:
Your app can use SMS API to transmit the DATA or other SOURCES.
My computer does not have any Bluetooth capability, however it has WI-Fi capability. My phone has both.
I was asking myself if there is anyway to "stream" Bluetooth over WI-Fi?
Thanks!
The short answer is no. Easiest would be to purchase a bluetooth dongle for your computer.
Yes, tunneling one type of communication through another is generally possible (within the limits of the Android Bluetooth API), but as it is an obscure need you will probably have to write the bridging server to run on the Android device yourself - this is after all a site for questions about software development. Additionally, it will work best when the app hosting the server is in the foreground, as Android makes no guarantees about keeping services running in the background.
On the PC side, this bridged Bluetooth capability will probably not trivially present as an ordinary Bluetooth adapter, so you would be limited to using custom applications which known how to talk through your bridge. The exception would be if you also spend time figuring out how to write a device driver for your host operating system which presents it with traditional Bluetooth APIs, at least to the greatest degree possible.
I have an android app, it does the following:
Connects with a server to read and update a database at the same time as others.
I want to convert this to an app that does not need an internet connection. Therefore i would like to know if its possible to have an android device acting as the server with the database, whilst multiple phones connect to it via bluetooth getting and updating the information in the database?
Thanks
Yes. It possible.
However all of your devices will have to be located nearby, so they can connect to each other through bluetooth.
You can take a look at Android Bluetooth API.
However, my recommendation would be to use Wifi instead of Bluetooth. YOu will need additional WiFi router. However, you won't need to deal with Bluetooth API in such case.
You will only need to write a server on one of Android device and the rest of devices will work the same (as now)
There are a few options to doing so, that don't involve a server. Both of them require a slightly different approach than both devices connecting to a server.
Wi-fi Direct- Only available with Android 4.0+.
Bluetooth
Personally, I have been using the Bluetooth option, and not found it terribly difficult. Essentially, you have to do the following to make it work.
Have one of the devices listen for a connection. If it is unpaired, you will have to make the device discoverable.
The second device needs to initiate a connection. It can do this by looking at the known devices and trying to connect to one, or listening for a new device
After the two devices connect, they must initiate some kind of a communication protocol. The communication is essential a serial connection.
Blue-tooth requires that the devices be within about 10 m of each other. Wi-fi direct will allow somewhat further, but as mentioned, is less supported. It is possible to allow for both communication methods, but is somewhat challenging.
What is the best way for an Android app installed on two devices to communicate with each other? Can the devices connect directly without using text messaging?
You have several options, depending on your requirements and setup:
If your devices are very close to one another (up to about 10 meters), you can communicate using Bluetooth, as Derek suggested.
If your devices are somewhat further away, but within WiFi range of each other (up to about 100 meters), then they can communicate with each other using the Peer-to-Peer WiFi API, documented here (part of the Android Wireless API). This does not require a WiFi router to be present, and the devices will find each other and communicate directly. This does however require Android 4.1 or higher.
The Android Wireless API will also work if your devices are on the same local network (i.e., use the same WiFi router), even if they are not themselves within range of each other.
If none of these options are viable/guaranteed, then I agree with Derek that the easiest way would be to use ServerSocket and Socket to create a server/client interface through the Internet. Here is a sample application doing that. The main problem you might encounter is that if the server is sitting behind a NAT (such as a home internet router), you will have to configure the NAT to forward the incoming packets to your Android server.
You can connect them via bluetooth using BluetoothSockets. Android developer website has pretty good documentation on this.
http://developer.android.com/guide/topics/wireless/bluetooth.html
Or if you'd rather (and have internet on both devices), you can use regular Socket's.
http://developer.android.com/reference/java/net/ServerSocket.html for server side
http://developer.android.com/reference/java/net/Socket.html for client side
If you have a large amount of data to transfer, internet sockets have a greater data capacity and will be faster. The other advantage is that there is no such thing as "out of range". You can connect the two devices wherever internet is available, whereas with bluetooth they have to be within bluetooth range of each other
you can use PubNub. it handles all networking and you should only care about messages.
it has great API to work.
(Thanks to #Ian Jennings : Can we send data from an android device to another android device directly (p2p) without server in the middle?)
Depends on what you are doing. If you have a server, you may be able to send some message to it and have it pulled by the other device (assuming both clients have the app installed). I think this would be the most intuitive way (but it really depends on what you are communicating).
Text messaging and email might work, but you (or the user) needs to know the numbers/emails associated with a device to do that.
you should have a look at WifiDirect
Wi-Fi peer-to-peer (P2P) allows Android 4.0 (API level 14) or later
devices with the appropriate hardware to connect directly to each
other via Wi-Fi without an intermediate access point.
As was already suggested, sockets are the easiest way to accomplish this if your devices are all connected to a network.
There are things to accomplish here:
Use Network Service Discovery to find devices running your app
Connect to other instances of your app using a socket
For a complete tutorial you can check this out
ShortAnswer: Yes
Data can be sent directly.
In order of range:
1 Bluetooth
2 wifidirect
3 maybe.. GSM hardware direct?
After that, options again in range order:
4 tether or network
5 Internet
The android NSD API is meant to do the exact same thing you are trying to achieve! The example bundled with SDK is self explanatory!
please check:
Android NSD API example