I want to control my arduino board by my own c++ or java programme. Basically I want to get values from arduino. And perform some tasks based on that values. Simply,I have connected a potentiometer to arduino and I want to read its value in my programme.
You can use the telecommand to control the arduino from your pc. pc will send a string, and a program for the control of the input string on arduino
Your question is very broad so its difficult to give a direct answer, but the normal way is to use serial coms via a USB cable. In your Arduino code use either Serial or SoftwareSerial to open a connection. In your C++ application you will open a connection to the same COM port your Arduino is connected to.
There is some example code on the Arduino website:
http://playground.arduino.cc/Interfacing/CPPWindows
It's then up to you to decide on a protocol for passing data back and forth. This depends entirely on your needs, so we can't really help you unless you give more information.
For my scientific collaboration, I wrote a C++ server/client (terminal server for linux, and cross-platform GUI client using Qt) that is mainly meant to transfer data from multiple clients around the world to store it on one server for analysis (pretty much like LIGO and Virgo that caught gravitational waves). For the communication low-level protocol I used boost::asio::ssl.
The "odd" part: In my programs, I created my own half-duplex messaging protocol between the server and the client from scratch. The messaging was in string form containing the version of the protocol, endianness of the computer, length of the message, type of the message (login/file/error/etc...), an MD5 hash for verification of the completeness of the transferred data. I got highly criticized on Stackoverflow chat when I said I did this. The part that got specially criticized is: Writing my own messaging protocol.
Now I created this, and I know there should be better protocols that are already written that I shouldn't rewrite it from scratch. However, I wanted to learn how to do this myself, and I did, and the program works, and my collaboration is satisfied, and the sky is blue with birds singing.
My question: If I am to rewrite this program again, what kind of libraries should I use? I'm looking for a protocol, using which I can send messages/data and get the server to respond with messages/data, including username/password to authenticate the user before any communication is transferred? How would you have done it?
PS: Please consider this question coming from a beginner in writing network and internet wide programs. And please don't hesitate to ask for more details.
Background
For my project, I'm attempting to control an AUV using an Arduino mega with an ethernet shield that receives instruction from a laptop (running Windows). The server side (laptop) will be written in C++.
Since there'll only be a one to one network using TCP/IP, I am trying to avoid the use of routers in order to simplify the hardware. I found out that you could do a direct connection between two devices (with auto-MDIX).
Therefore...
I have briefly looked into Boost:asio but I think it's probably an overkill (because I won't need to consider multiple clients etc) crossover for what I'm trying to achieve here. Am I right?
Any advice would be appreciated! Thanks.
TL;DR:
Looking for a C++ networking library (that works on Windows) that allows a clean, simple code to do a one-to-one TCP/IP connection.
The simplest way is to set-up your arduino as a web server. See this example sektch for the details.
On your Windows box use a web client library.
This way you can test the arduino even without your client software using your browser.
I'm currently working on transitioning a small console application to a TCP server / client application. The client will connect to the server via any Telnet client, and the server will replicate the standard console interface for each Telnet connection.
I started looking into doing this using the techniques I've learned from Beej's guide to network programming -- accepting the connection and then using fork() to separate it into its own process.
However, I would prefer to maintain my use of streaming IO (the original console application uses cin / cout, using similar functions for the networking logic would make the conversion process much simpler).
I've discovered the TCPStream class, hiding within sockets.h (http://www.gnutelephony.org/doxy/bayonne2/a00215.html)
It appears this class will allow me to use the server with streaming IO. However, I can't find a single example of using this class, nor can I find an explanation as to how to use fork() with it.
Any ideas? Thanks in advance for any help.
I think you are confusing the trees for the forest. One socket class is such a small part of what you need to do overall that it is not worth focusing on that.
If your objective is just to get your project working then just use an existing framework rather than trying to pull individual classes out of a large project. POCO has a TCPServer class that will do 90% of the work for you. QT, ACE and others have similar classes. There is not a huge amount of documentation on POCO but they do cover TCPServer pretty well and you can learn a lot from reading the source code if that is really where your interest lies.
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I have one computer that is running a c++ program to control a robot and another computer that is running a computer vision system (also written in c++). I would like for these two programs to be able to talk to one another. The communication would not have to be complex, I would just need the robot computer to be able to tell the vision computer when a trial begins and ends (when to start and stop a data collection sequence). Do any of you have advice on how to approach this problem? Rs232 communication between the computers? Some kind of networking solution? smoke signals? Any suggestions would be welcome.
thank you in advance
(edit) In case you think the statement above is vague:
I need to pass a binary (go/don't go) signal from one computer to another. Unfortunately I can't be more specific about what this will look like because (obviously) I don't know what is available. Both computers are on a network, and both computers are running windows. The goal is to syncronize data collected by the computer vision system with actions performed by the robot. The communication does need to be fast enough that it will not slow down either the robot or the computer-vision program. a "good" solution would be 1) easy to implement 2) fast. I do not know much about networking and I am looking for a place to start looking.
thank you again for your assistance
You might use a simple UDP protocol - the advantage being that if you understand the concepts of simple packet protocols on RS232 you'll find it easy to transfer that knowledge to sending the packets via UDP.
If you want a reliable (as in, other parts of the system will worry about errors and retries) stream of bytes between the two PCs, then TCP/IP is not much more complicated to use than UDP.
Both UDP and TCP are accessed through 'sockets'. I'm afraid you'll find that from C++ there is rather a lot of tedious boilerplate to getting that working, but there are lots and lots of examples around.
If they are network-connected you could just use sockets.
The best option will be to use network communication. The easiest way to approach this should be to look at the networking examples in Qt.
You basically will create a client and a server application. You decide what the client does when it sees a certain message from the server. That's all. Qt should take care of the rest of the stuff.
Other answers suggests TCP/IP, UDP, RS232, ... All those things are just options when you use QtNetwork module. I assume that since you ask your question, you don't know about the difference between those. So the safest bet will be to use the highest level (free) library, hence the suggestion to look into Qt.
Another option is to use Boost.Asio. I tend to prefer Qt solution since their API is nicer.
That sounds like a fairly good use for the network socket. If both your machines are on Windows you can even use named pipes.
For Windows, you will need to open the COM n port as a file to communicate over a serial port[1]. I don't have access to my code now, I can look it up when I get home.
RS232 is easy and I like it. However, it it is slow. You need to consider that in your design.
[1] For C++.
Most modern computers have Ethernet capability, so get yourself a cheap hub or switch and look at networking APIs. There's usually some fairly easy socket stuff. One advantage of this is that, if you want to increase communication ability later, such as having your vision software provide instructions and guidance to your robot, you've got the basics set up.
Alternately, set up your vision program so you can start and stop it by hitting random keys. When you're going to use it, put the keyboard in front of the robot computer's CD drive, and eject at the start and end of the robot run.
This may be overkill in your situation, but if I were in your shoes I would probably implement it using the HTTP protocol. The vision computer would run a HTTP server and the robot computer would communicate the state changes using POST requests. The Poco C++ Net library provides you with the facilities required to do this.
I would use a TCP/IP socket for communications. TCP guarantees that the data will make it. So, all you need to do is parse the data.
RS232 is an easy option to program for, however modern PCs don't tend to have RS232 ports. You may need to get USB-RS232 adapters or install a PCI card.
The other problem with RS232 is that you have an additional wire to worry about which can be a nusiance. Also RS232 cables can be limited in length (5-15m) unless you invest in some clunky RS232 repeaters or bluetooth connectors, etc.
On top of all that you're also adding one more item to your project that can go wrong and cost you time in deploying and debugging.
IMO, an elegant engineering solution would be to utilise the hardware that you have and use TCP/IP sockets to communicate.
The web is awash with examples on passing messages between servers and clients:
If you're using Linux:
http://www.linuxhowtos.org/C_C++/socket.htm
Using Windows:
http://www.adp-gmbh.ch/win/misc/sockets.html
I also might look at something like 0MQ to make the connection more robust. It will transmit and reassemble messages regardless of the transport, and handle buffering in the case of temporary loss of connectivity.
But the bottom line is that I would use TCP/IP, but depending on the nature of the robot you may want a slightly more robust connection system than TCP sockets. UDP is nice because it's connectionless-- if the robot temporarily travels out of range/sight/etc you wont have to rebuild the socket and context.