Good afternoon. Please help in creating the application.
A project is being created to control the air suspension of the car through Arduino. The application is written in App Inventor. The connection must be established via Wi-Fi.
Q: how do I do this in App Inventor? What are the blocks? So that when you start the application, it is immediately connected to Wi-Fi.
I don't think it's necessary to auto-connect your Android device to WiFi. The connection over WiFi method is much user-friendly to connect it manually. But, if you intent to do this, you could use TaifunWiFi.
hope this help.
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So, I have created a normal Bluetooth app and I did faced many troubles for trying to connect to a device (Only Bluetooth headphone)from the app programmatically. That's why I thought that I would lead the user to the Bluetooth setting page using intent and it all works till now. Now I am trying to know if it is possible for me to redirect the user to app after he connects with a Bluetooth device from the Bluetooth setting page ?
The code is in JAVA
Anyone please help me with the connection problem I am facing. The app only connects to Bluetooth headphone and nothing else. If anyone has a working code for the connection in Bluetooth it would be a great favor
I am starting ROS on Ubuntu 20 on Raspberry PI with setting ROS_HOSTNAME to $(hostname).local and ROS_MASTER_URI to http://$(hostname):11311.
The problem is that if I am connected to WiFi and then that connection fails (for example if WiFi goes out of range), then the robot stops working correctly.
I was thinking that a possible solution could be to create a new network interface or a VLAN and start ROS on that network and then bridge that new network to wlan interface. This would make the network that the ROS is connected to independent from wlan interface, but it would still have access to network if wlan would be online. I would also like to keep the possibility to connect to robot's ROS through another device on the wlan network.
I am asking here for help because I don't have enough networking knowledge to make this work. So any guidelines would be appreciated. If there is another better approach to solving this problem, please let me know.
I suggest using ros_bridge for communication with the robot. It is often used if you have a web interface for your robot and you need to visualize some data from the robot's backend on the web. Or even send a command to the robot.
The counterpart to this node is the roslibjs library. You can find it here
For more info, you can check Robot Web Tools, a collection of tools for web-based robot apps.
However, maybe you are not interested in web apps; you can still use ros_bridge with roslibpy which is python implementation of rosbridge protocol. It is the same as roslibjs, but this uses python instead of javascript.
You can easily create a python app which will use roslibpy to subscribe or publish to topics or call services.
This approach is better because you will encapsulate your robotic backend, and you can control what is visible to the outside world with params for the ros_bridge node. You can also handle better reconnects if your robot lost wifi connection.
Still, you can use exposed ROS_MASTER_URI for rviz and debug proposes, but I wouldn't try to use it for controlling the robot because the connection between nodes won't be recreated if you lose wifi connection.
In my work, we used ros_bridge for some time in production AMR, and I have to say that it wasn't as robust as I thought initially. For example, there were issues when the robot changed the wifi access points, and caching messages didn't behave according to the documentation. For the web, we still use it but to control a fleet of mobile robots, we had to abandon it, and we developed our solution based on rabbitmq.
But I guess that if you are using Raspberry Pi, then it is not a production robot, and therefore I think you should be OK with ros_bridge.
I am using Sample App of Bluetooth Chat.I Have one problem I want to search only those devices on which "BluetoothChat" is installed. Please help I am new in android.
It can't be done. All you can do is try connecting them all, if the connection is refused, you will know that this device is not running your app.
That is not possible.because you did not check package name of your application in another device before connectivity via bluetooth.If you want to connect only tab or mobile device then this can easily possible.
Im developing a mobile application in j2me.In my application i connect the mobile with some other device with respect to bluetooth.After connection established i send the command from the mobile to that other device to perform some operations via bluetooth.
Here i does not know how long bluetooth connection remains.Im using javax.bluetooth package.
So please tell me how long (with respect to seconds/minutes,etc) bluetooth connection is remains after connection establishment,Or is there is any bluetooth connection time out in mobile/j2me.H
Here im using nokia s40 series is my targetted device in mobile side.
Im fresh to bluetooth technology.So please forgive my mistakes in the questions.All of them are welcome to provide their ideas.
Thanks and regards,
I want to consider all the connectivity possibilities in JavaME , connectivity between phone mobile and PC. Apart from bluetooth what are the possible means of such connectivity ?
You need to have a look at the Generic Connection Framework (GCF) which gives you the ablility to open connections using various protocols. You do this my using a Connector object.
It is obviously completely dependant upon the hardware upon the phone and any optional JSRs that it implements, but you can communicate to a phone via:
Using internet protocols e.g. Http, Datagram, Socket connections (Requires PC to be accessible via the internet)
NFC (Near Field Communication)
Using a Secure Element (SATSA)
Serial COMM port connection (I think)
I'll completely admit that using some of these methods to communicate between a PC and a phone are nuts but it could be done.
The best thing to do for simplicity is to use bluetooth or a HttpConnection.
U also able to connect mobile with pc via internet (Gprs).Better u look at the Generic Connection Framework (GCF) documentation.It will help u