Android: How to send and receive signals from a phone - android

I wanted to check if this is possible, i looked around in the net and i didn't find one answer.
Is it possible to use a phone via app to send a signal into a circuit and to receive the same signal back in the app?
Basically is there a library that i can use to work with such signals?
Thanks.

A phone, even smart, is not really intended to control an electrical circuit by sending it signals.
To do this comfortably, you need GPIO, ie pins whose you can control the output.
Your best bet is probably to buy yourself an Arduino, and to have it communicate with your phone over bluetooth.
You'll most likely have to develop your own application, as well as the program for the Arduino.
You could also have a look at the Raspberry, as it offers GPIO as well.
It might be a good tool for managing another circuit, but it all depends on what you exactly want to achieve.

Related

communication between multiple phones/devices

I would like to create an application where near phones/devices can send data between each other.
it should look like that all devices except one turn on some listening function. One device create game and add each of devices from list to game.
I know how to accomplish this task with use of intermediary server. But I would like to achieve this in a different way without server. For example I can create app which find near ibeacons and displays them in a list, and get data from them. Is it possible to make to way communication by bluetooth between phones with bluetooth?
Maybe other technologies? I do not want to use NFC, because range is to short.
Another limitation is that, this solution should be an cordova/phonegap plugin?
Edit:
I need to communicate between users devices. For example I want to make app where two users standing near each other chat together. Messages should be send between phones, without server.
It sounds like iBeacons is the perfect solution for what you're attempting to achieve. It doesn't require NFC or a server–only devices that have Bluetooth 4.0 LE (Low Energy).
If you're unhappy with iBeacons, I recommend the Multipeer Connectivity framework that also became available in iOS7:
https://developer.apple.com/library/ios/documentation/MultipeerConnectivity/Reference/MultipeerConnectivityFramework/
Here's a good tutorial on AppCoda:
http://www.appcoda.com/intro-multipeer-connectivity-framework-ios-programming/
Another benefit to using the Multipeer Connectivity framework as opposed to iBeacons, is that it doesn't require Bluetooth 4.0 LE, which isn't available on iPad 2 and iPhone 4 devices.

Can you manipulate Raspberry Pi sensor data on an Android smartphone?

I am new to using the RPi and just got the A+ model which I have been using to generate different types of data from external sensors. I was wondering if it is possible to send this data it is gathering to an android device in real-time, and if so the best method? I want to be able to notify the user (through a an app made with the Ionic framework) when the data enters a particular range etc.
And also is it possible to do this whilst the user is walking around with both the devices in hand?
The short answer to the question is: Yes, you can ;-)
The longer answer is much longer, since there are many ways to do this.
The one I personally would choose as the simplest is classic Bluetooth (not LE) using the SPP profile, which basically makes the BT link a serial connection between the RPi and the phone.
On this serial link you invent you own streaming protocol suitable for the data you want to transfer.
On the RPi side you install a module such as this: https://www.sparkfun.com/products/12577
(There are many alternatives, but the RN42 module is very foolproof...)
Don't know the level of your hardware skills, you might need something more plug and play if you feel uncomfortable hooking up the 4 wires needed for 3.3V power and serial communications between the Pi and the BT Module...
On the phone side you install https://github.com/don/BluetoothSerial, which gives you an API reachable from Ionic where you can receive the BT data stream.
With that and a bit of coding on both sides you are good to go.
I've used a Raspberry Pi in combination with an Android smartphone & Lego NXT.
Communication was achieved using Bluetooth on Raspbian. I used a cheap $1 USB Bluetooth dongle. The Bluetooth stack had to be compiled for Raspi, which may not be necessary anymore. Steps can be found here: Bluetooth error: Native Library bluecove_arm not available
Bluetooth seems most logical to me.
I'm at work at the moment, hence the lightweight answer, if you'd like to discuss this further then please leave a comment and I'll be happy to provide more verbose response.
You can upload the data to any cloud services. You can use Xively/Box. Xively is specially made for real time data collection.
To connect RPi to Xively, refer this: https://xively.com/dev/tutorials/pi/
For Box, refer this: http://www.sbprojects.com/projects/raspberrypi/webdav.php
You can then use Xively API in your android app. You can see GitHub for this
Google app store already has some apps for you, if you want to use
It might look a little complex. But its really simple once you follow the above methods.

How to sniff Bluetooth traffic in Android?

I would like to know if there are any apps/api tools to track all the bluetooth connections happening in android? I tried using hcidump via BusyBox, but the trace is truncated, it does not display all the data I need.
I am trying to receive data from blood pressure monitor in android using Bluetooth HDP profile. However, the connection works at the beginning, and then stops. Therefore, I would like to use some packet sniffer to see the low level bluetooth connection for better debugging.
I found out that traces from hcidump tools are not truncated, and I think this is a perfect solution. However, I have to copy the trace from android to the pc evry time (e.g. sending by e-mail) and therefore it is a cumbersome work. Would be great if there was a tool to get access to the terminal emulator of android. Btw, BusyBox provides also some other very useful tools from Linux.
There are two options for this currently, the first is to use a software-defined radio that supports the ISM band (at least 2.4 to 2.485 GHz). This will allow you to grab any radio signals within the bluetooth range and will be especially useful if you're trying to identify interfering signals.
The downside is that you'll be receiving totally raw waveforms which you then need to demodulate using something like the gr-bluetooth stack.
The other option is a specialized device like the Ubertooth.

LED control from android without using arduino and similar costly boards

I want to control an LED from an android application, Can I do it without arduino or similar costly boards, I need only an on/off control from a button in my android app.
Short answer: no.
Long answer: You'll need any kind of harware, receiving the signals from your application. The cheapest method might be to use an arduino. However, you have to develop an arduino server, which can be quite difficult.
If you have an old cell phone around, you can use that as a receiver. have a look here: http://www.youtube.com/watch?v=5tHlJLQvE1Y

Make a mobile device a remote control for a tablet?

I'm trying to make an app on an Android device that will control an application on an iPad or Android tablet. (I'm testing with an Samsung Galaxy S2 and an iPad 2).
The application is pretty simple for now. When one selects a colour on the Android mobile, that colour displays on the tablet device.
The question is, how to connect the two devices. Just now I've verified that I can pair the two devices using Bluetooth. Also, the Samsung has a "Kies" Wifi Direct feature (which I don't understand fully), that allows the iPad to connect to the Galaxy as a wifi hotspot.
The connections are there, but I don't know if either protocol can be used to actually get the apps to talk to each other to get the control I'm looking for.
Should I be using Bluetooth, Wifi, or something else?
And in whichever case, how?
My opinion is that you should not stick so much around the physical medium used for connectivity either is WiFi or Bluetooth. You should abstract this aspect, in both cases you will be using sockets (I'm speaking about Android), if it's Bluetooth you will be using Bluetooth Sockets, if it's WiFi: TCP sockets. You could have a intermediate layer that abstracts the type of connection and through a factory to use either Bluetooth or TCP.
Bluetooth - http://developer.android.com/guide/topics/wireless/bluetooth.html
For WiFi you should study if P2P would help.
You will need two applications:
- one on the tablet - the server which listens for commands from the client (change color, do this or this)
- second on the smartphone - the client which sends commands.
I've built a few apps that do exactly that between iPhone and iPad. But the principle is the same. I used Bonjour networking. It's just a fancy name for ZeroConfig networking between devices. It's written originally by Apple but it's open source so there should be Android support out there for it too. Really simple and easy to work with.
If you already have a working connection then you already have the first half of your answer, that said you should really consider implementing a solution that uses a variety of connection types, WIFI, Bluetooth, etc.. The question I think you are really asking is how to pass data and messages between the apps once you have the connection.
There are a lot of ways to accomplish this. You could implement your own lightweight message passing system. If you haven't done this before it is more complicated than it originally seems, especially as you would be required to implement the system for each OS you end up using.
Should I be using Bluetooth, Wifi, or something else?
It depends on what situations you want your program to work in.
Bluetooth can provide a direct connection between your devices. A potential issue with bluetooth is that it has a limited range. If you're devices need to be far away from each other, you may want to go with wifi. Otherwise, bluetooth could work great.
If both devices are connected to the internet, you can make them talk to each other through there. The advantage of this approach is that it doesn't matter how far apart your devices are as long as they're both online. A disadvantage is that you'll have to figure out how to find the tablet's ip address before you can talk to it. This is actually a HUGE disadvantage because it can be quite problematic if both of your devices are not on the same wifi. You could have the user type in the destination ip address, but you'll have problems getting it to work if the user is behind a router (which will almost always be the case). The point is, it gets hairy.
If both of your devices are on the same wifi, you can use ZeroConf AKA bonjour (like Dancreek said) to figure out what ip address you need to send info to. I've previously used a library called jmdns (easy to find with google) to implement zero configuration networking. It's good because the user doesn't have to worry about ip addresses... it's intuitive for the user.
And in whichever case, how?
Networking is a pretty big topic, so I can't expand on this question to much. Short answer is, it depends on what method you choose. Search for some tutorials and start by getting one of your devices to send something as simple as an int to the other.

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