So right now, I'm currently using the TI SensorTag and edited it such that it will send a GATT notification with some data every time I press one of the switches on the device and followed this code where moisture is the data I'm trying to send.
static void sendData(void )
{
int length=0;
while(moisture[length] != NULL)
{
length++;
}
attHandleValueNoti_t nData;
nData.len = length;
nData.handle = length;
osal_memcpy( &nData.value, &moisture, length );
// Send the Notification
GATT_Notification( 0, &nData, FALSE );
}
Now on the Java side, TI provided the SensorTag app source code so I'm editing that to receive the data and save it into a .txt file for later retrieval. I was able to get the app to create a new directory on startup if it does not exist and create the .txt file and populate it with random strings with the same button press as the one used to send the data. A quick question I had about this is should this be done or should I use separate buttons?
What I'm having a huge issue even understanding is how to read the incoming notification or data. From what I understand so far, you need to know the characteristic or something of the incoming notification to read it? I do have notifications enabled on my central device so I know that I have at least that covered. For this kind of data transfer, I don't need to use any UUID things, correct? And if I do, would I be able to piggyback on one of the existing sensor services to do so? Or perhaps use the test service?
I've read a decent amount on BLE communications but I just can't seem to get it. How do I read the incoming notification or data I sent from the SensorTag through BLE?
A quick question I had about this is should this be done or should I
use separate buttons?
It's totally your call. If I were you, I would stick on to one button since BLE devices are better if designed the most simplest way. KISS.
From what I understand so far, you need to know the characteristic or something of the incoming notification to read it?
Yes, you need the same profile running on both the peripheral and the central to enable notifications. In Bluez for example, run the bluetoothd daemon with all experimental profiles to communicate with a TI Sensor tag like this: bluetoothd -E . The same logic applies for a central running on Java. Reference: http://www.amazon.com/Inside-Bluetooth-Communications-Sensing-Library/dp/1608075796
For this kind of data transfer, I don't need to use any UUID things, correct?
No, you don't have to since you aren't creating a new service but rather using the moisture sensor service already available on the device.
I've read a decent amount on BLE communications but I just can't seem to get it.
To know more about Bluetooth terminology such as profiles, services, characteristics, asymmetric architecture, etc, please read the following references to understand the theory behind what's taking place:
http://www.amazon.com/Inside-Bluetooth-Communications-Sensing-Library/dp/1608075796 (use this if you are already into the technical details of the project)
http://www.amazon.com/Bluetooth-Low-Energy-Developers-Handbook/dp/013288836X/ref=pd_sim_14_1?ie=UTF8&refRID=13KZ3RZ0VW93CK91RCM3 (this gives a more general picture of the BLE)
Related
I'm currently developing an android app for a weight scale I received that transmits data through bluetooth low energy.
I was looking at documentation and if I got the information correctly, there are specific UUIDs for data. I received a BLE scale with a Chinese protocol document found here: http://www.anj.fyi/protocol.pdf
I found and was able to get a functioning scanner working that lists the device name and the UUIDs it broadcasts.
Lets say I want just the weight data to show up in the UI, nothing else and nothing more.
I don't know what UUID they used for the weight data, and there are a lot of UUIDs. Probably 20+. I checked a UUID compilation and the usual weight data UUID does not show up.
How do I get the data from those UUIDs?
I'm thinking it might be the ones that are notifications, indications or read properties.
Looking at the UUID for example, f000ffc2.
How would I get data from that characteristic? Would anyone have an example code to grab the data from those UUIDs, or tutorials because I'm terribly lost right now.
I really appreciate it.
There are no weight information on the document you list http://www.anj.fyi/protocol.pdf, it is only shows the BLE module hardware interface spec, i.e. it does not specify the detailed service and characteristic.(I an a native Chinese speaker).
Regarding to the UUID you want to know which is the one to represent the weight, yes you are right it should be the read/notification feature without write permission. Can you use the apps e.g. lightblue on iOS to receive the notification(meanwhile change the value on your device) to test it? this will help you to understand which characteristic is the one you want.
Q. What are your best practices in managing bluetooth connectivity?
I've read the android bluetooth guide & many bluetooth connectivity tutorials. Not helpful with encapsulation-design nor best practices.
When should I open/close the connection?
Is the "connection" with a single bluetooth device called a "socket" connection?
Can a single connection send data while listening? (...or between listening states).
I've never coded connectivity with external devices before. It took two weeks for me to wrap my head around the code that scans for near-by bluetooth devices and throw them into a ListView. Listeners, Broadcasts, and Adapters!
My project will be printing 1-40 receipts every 15 minutes on a bluetooth receipt printer. At the moment, security is not an issue. On the same connection, it will also be receiving data (sending & receiving simultaneously does not appear to be necessary but would be useful). I'm not yet sure how the devices are configured on this single dongle device but I would guess the devices are connected via USB controller to the dongle.
So far, I have 1 object to manage a single I/O connection. Staticly I open an activity to select a connection (to later save the label, mac, and pin in the database). Based on tutorials, I have "open", "listen", "send", and "close" methods. What confuses me is "how" to use these functions. Can I leave a connection open all day (10hrs) and use it every 3mins? Should I open/close the connection when sending or requesting data? Where would I detect the need to reconnect?
sorry for the short answer, but from my practice with the Bluetooth API, I have found that this video describe the things very good (totally personal opinion...)
Video 1
In addition this is useful when you do NOT have any previous experience
Tutorial
And as last check out this question in stackoverflow it has a bunch of good references and examples!!
Again sorry for the shortage, but I believe that if you check these out at least most of your questions and concerns will become answered!
:)
EDIT
So, let me be a bit more descriptive and share some of my experience.
I have written an App that communicates with BLE device that has 3 functions
double sided event driven button (push the button on phone -> event is fired to the device; push the button on the BLE device -> event is fired to the phone)
send request from phone -> BLE device answers with current battery percentage
continuously reading strength signal (as aprox. distance) between the phone and the BLE device
So far so good, now the things is that the basic approach is:
Search for BLE devices (bluetooth search or "discovery" of nearby bluetooth devices)
Here you will need android permissions!
Choose the device you want to connect to
To differ the devices (maybe there are a lot around you :) ) you can use BLE device's name or UUID or ... best - use the name ;)
After both devices connect to each other you can then start the Gatt communication. The approach with state machine is a little too much overkill for me. But anyway the communication is done through bytes (in my case...)
In one of the videos/resources there was something specific and VERY HELPFUL at least for me! To be honest I don't remember it exactly, but the idea was that before any communication it's RECOMMENDED to read/get all the options from the BLE device or something similar...
Maybe it was something like discoverOptions() or something like that
Great thing will be to know your device "communication codes" or at least I call them that way.
Check this link for example: Link
** Now you can see there are tables with the USEFUL INFO! E.g. if you want to read the battery level you navigate to this page and find that in order to read the battery, the service name is UUID XXXXX and you need to send 0x01 to the BLE device and it will "answer" to your call with some data which is again in bytes.
I really hope that this is somehow helpful!
PLEASE NOTE
This is strictly coming from my experience and there could be some mismatches or wrong terms, but that's how I personally see the things and because my project was long ago, I don't remember most of the things exactly.
IMPORTANT:
This is only a summery of STUCI's provided links above. He has since updated his answer and I have not updated/edited this summery. Topics in my summery are not explanatory but provided for reference and help in generating specific questions.
Original Post...
Thank you Stuci! Some of that was helpful:- some not. I thought it best to collect my thoughts and see what has been explained and if anything hasn't.
(I can't post this much in a comment tho, sorry)
PLEASE CALL ME ON ANYTHING THAT IS INCORRECT.
Video of Bluetooth LE
(Covers a bunch of random things)
While I "dont-like" videos of code:- I watched it because it was recommended ... and I am glad I did. While not very helpful it did introduce some concepts I was unaware of. Since I am targeting old android devices (v8+) the LE features are inconsequential.
Pushing Data: [Depending on the source feature-set], one does not need to continually pull data (ex. with a temperature sensor) but some devices can "push" it to the device on change. Seems to use the 'advertisement" design concept.
UUIDs define Services and/or Characteristics of the connected device.
Possibility to write configuration on (to) connected devices.
Characteristics which seem to be simply "settings" that can be assigned over bluetooth. Not sure if this (~19mins) applies to non-gatt connectoins but seems similar to the state-machine that controls
Advertisements which seem to be the "metadata" regarding the devices current state or config (~24mins). Again, not sure if this even applies to non LE Bluetooth.
Leaving Connections Open
Bluetooth connections can indeed remain open; starting at the point which the "startActivityForResult(...) method is successfully called.
Two basic things affect whether or not one would want to maintain an open connection:
Understand the power consumption.
Having the adapter active simply consumes additional power. If one can keep the adapter shut-off while it is not "absolutely-needed" will mearly save battery power.
Accidental disconnects are managed.
Other than leaving the connection continually connected, one could disconnect & reconnect regularly at specified intervals to ensure a connection is up.
In the thread(s) used for I/O, one could check for a disconnect and reconnect (possibly starting a new thread).
I/O Streams pr Connection
A single connection can indeed "have" simultaneous Input & Output streams. I
Since it was suggested, I re-read Android's Bluetooth Guide and under "managing a connection" (talking about a single socket) I noticed this...
Get the InputStream and OutputStream that handle transmissions through the socket, via getInputStream() and getOutputStream(), respectively.
Read and write data to the streams with read(byte[]) and write(byte[]).
...but continues with noting that read & write block each other. Something I still need to look further into. It seems like you cant I/O simultaneously on the same socket???
Max Connections
I also looked into the max connection issue Stuci added and found no documentation on the Android-side. It might exist, I cant find it. However, most people seem to agree that there is a limitation (that could be as low as 4) imposed by whatever hardware you are coding for.
Some notable links:
- How many devices we can pair via Bluetooth of BLE to Android?
- How many maximum device can we pair via Bluetooth to android device at a time?
- https://groups.google.com/forum/#!topic/android-developers/adeBD275u30
My goal: Make my phone control an Arduino which controls servos which will do cool animations.
How do I get to my goal: I use Java to communicate to the Arduino Nano through the yellow pins (visible on the right picture) through serial (RxD/TxD) (RS-232 protocol) which will tell the Arduino how to control the servos or motors.
Problems:
I don't know which one of the pins that does what, like which one that is GND, which one that is TxD or RxD
I don't know how to tell the phone to do things with its yellow pins (which the Arduino will read and understand to control its servos/motors)
[_] I don't know how to listen to the phone's accelerometer through Java - The thing that lets it tell what is down
[_] I don't know how to listen to the phone's light-sensor
[_] I don't know how to listen to the phone's microphone
[_] I don't know how to listen to the phone's camera
[_] = Things I'm just very curious about that I will use for future projects.
Extra information: I got NetBeans IDE 7.1.1, and I got an Arduino Nano, I got the phone shown above which is called "J10i2 Elm Sony Ericsson".
So I guess what I'm really looking for is someone who knows how to control a phone 100% through Java. Or being pointed in the right direction is also nice!
If you think that I can do this in a better/simpler/smarter way then feel free to leave a comment stating why and how it is better ;)
I would suggest one easy solution, use a REST web service (SOA arquitechture) to solve this problem i did it in my personal case and now im able to control and monitor my house :)
You could simply create a database table representation of your arduino's pins...then just create a service that receives some parameters (i.e> pin no, status -> 1/0, arduino id, etc) and saves them in the database, with your mobile app you could just use the same web service for changing the values.
Finally write down an Arduino app that keeps reading statuses from that service and database (of course using another endpoint/ method in which case you just need to pass your arduino id and it will return a response of all of the different pin status so you can read/process them from your arduino (for example since JSON library is heavy and slow on arduino im passing my return values back from the server to the arduino using simple CSV values i.e> "[pin:status,.....]" i have some code for making HTTP/GET/POST on Arduino you just need the ethernet shield , i could bring you the code if you are interested
I am writing a Red5 application that provides 1-on-1 video chat to a Flash client over RTMP.
Unfortunately most tutorials I was able to find were sketchy at best and the documentation of Red5 itself tends to be vague when it comes to API concepts and intended usage.
In short, I am a bit stuck and looking for hints on Red5 ApplicationAdapter implementation. Gnarly details are as follows:
First of all, the connections come in two flavors: visitors and consultants. A visitor should be able to indicate which consultant it wishes to communicate with. A consultant simply gets connected to the requesting visitor as long as the consultant is not busy servicing another.
Obviously, every RTMP connection has two-way traffic: both sending and receiving video. From the standpoint of the server, connections bring in a bunch of video streams that get their receiving endpoints assigned by request.
Since several video conversations can be in progress simultaneously, the main task of the application is to handle the mapping of visitor streams to consultants and provide a list indicating each consultant's state (busy/available) via AMF.
So, all in all, I have a pretty good idea what I am aiming for but how to achieve it with Red5 is still a bit of a mystery.
Hopefully someone can enlighten me in any or all of the following:
What is the easiest way to establish the connection type (visitor/consultant)?
Which API classes should be used to implement a persistent, globally accessible list of active connections for reporting the state of each consultant?
How to switch receving endpoints dynamically when the goal is to connect a specific visitor to the selected consultant?
Saul ,
1.What is the easiest way to establish
the connection type
(visitor/consultant)?
assuming that both(visitor/consultant) are using flex client via which they start publishing their live video stream ,here you need to make sure that each published video stream name is unique (HOWTO is already mentioned in demo apps)
2.Which API classes should be used to
implement a persistent, globally
accessible list of active connections
for reporting the state of each
consultant?
and for providing the list of active connections you simply need to store(preferably in your db) each user's id with the stream name (which is also available as a tutorial demo app) to connect to.
I believe all the code is available for the red5 demos Do try oflaDemo , simpleSubscriber , fitcDemo demo apps.
I hope I am closer to your solution.
Since Oflademo or red5 is capable of 1v1 chats, then replicate this code to make around 50 chats. You can maintain a table with the following columns :
chat room number (1 to 50)
user1
user2
status(0 or 1 - unoccupied or occupied)
If let say a visitor V22 wants to get consulted from consultor C33, then a program can detect the first unoccupied room from 1 to 50, if the 7th room is unoccupied then, redirect V22 and C33 to room 7 and change status to 1(occupied). After the video call, the status can be reset to 0, and the table at roomno:7 , user1 of roomno:7, user2 of roomno:7, can be set to NULL. Its like maintaining tables in a restaurant in a computer.
You can basically develop multiple chatting using 1to1 using a database and php queries, no need to edit any swf code or maintain a complicated server etc.
An Android app I'm writing involves quite a lot of downloading of content (think podcatcher/RSS).
I would like to be able to give the user an indication of how many bytes they've downloaded, so they can make the decision whether they want to use Wifi or not.
To this end, I have found a way of counting the number of bytes read by the app, by wrapping an InputStream in a simple CountingInputStream.
However, this does not take into consideration basic things like packet headers and HTTP headers. More importantly, it does not take into consideration any compression that content may be encoded with.
So, how many bytes did my application download over the network? I'm not so interested in the number of bytes uploaded, but if know how, don't be shy.
I have gone down a fairly low level approach as I am feeding the input stream into an XML PullParser. I will also be needing to do a similar exercise with dumping bytes (images in this case) straight onto the SD Card.
Is this the best approach? What am I missing?
ufff... I think this is pretty transparent to underlying protocol, so you can't count all these bytes used in session or link layer, and operators like to charge even for control bytes which are not in any way visible to end user. Also they count traffic in both directions (your reqest to server takes also some), so - good question is: how to measure needed traffic/money for downloading that picture... ?
This isn't a direct answer, but you could try asking someone who has solved a similar problem before, e.g. a data counter application. I've used NetCounter by Cyril Jaquier (http://www.jaqpot.net/netcounter/), and he claims his software is open source. I couldn't get his download link to work, but there's a contact email address. If you got his source code, you should be able to use the same method as him.
As I know, there are two ways to count data traffic. One is /sys/class/net/{interface}/statistics as mentioned in android app named netCounter, the other is /proc/net/dev which is used in android app named wifi-tether. But I don't know the difference between these two methods nor which is better.
The number of bytes received by a particular app is stored in /proc/uid_stat//tcp_rcv where app_uid is the uid of your app on the particular device.