Where can I find an example program in C to print to a network attached HP printer.
Printing requires a printer driver which handles all the task of communication with the printer.
all you have to worry about is how to print, the fact that the printer is networked or usb or parallel doesn't matter
If you're hardcore and want to use the windows API (assuming you're on windows)
otherwise you could simply redirect output from STDIO like this article suggests
It depends how you want to talk to the printer. Nowadays a lot of printers can support many different network protocols to receive jobs. So which is it:
IPP (Port 631)?
LPR/LPD (Port 515)?
AppSocket (Port 9100 and others) ?
FTP? RCP? SCP?
Anyway, for most of these cases you can find example code here: http://svn.easysw.com/public/cups/trunk/backend/ -- Further help here: http://www.cups.org/documentation.php/api-filter.html
(However, I wonder why you want to implement such a thing yourself on Linux...)
Related
I'm using a LPC178 development board and I want to read a file present on a Windows PC. My dev board only has a RS2323 interface to communicate with.
How can I go about transferring the file from my PC to my MCU using a RS232 (serial) link? I found a reference which explains how to transfer data between a MCU and PC but it isn't about file transfers.
Afaik there is no easy solution for this like calling something like "copy" or "fopen" over RS232. I would be happy to be proven wrong here.
The fastest solution might be to write a little programm running on your Windows Host, which listens to your RS232 communication and pipes your communication into/out of the file based on your communication protocol. This can be done with standard file operations in the language of your choice, for example C, C++ or Python.
Your problem is one of the oldest in the book. How do you transfer files without fancy operating system abstractions. For RS232 (or any other serial method) there exists many file transfer protocols.
One of them is kermit. This is a protocol from 1981 and can transfer binary and text files. It is able to be embedded in a micrcontroller and there exists programs to transfer/receive using kermit.
alternative old site for reference
In the simplest case you would use a file transfer protocol such as XMODEM, YMODEM, ZMODEM or Kermit - these protocols were designed in the days before networking and the Internet were ubiquitous and deal with simple point-to-point transfers between two computers. They are supported bu most terminal emulator tools such as TeraTerm Pro or PuTTY so no specific PC software need be written, just the microcontroller end.
A more complex but flexible solution is to implement a TCP/IP stack and a PPP driver, and an FTP application layer - probabaly only practical if using a third-party TCP/IP stack and application layer. You can then use any FTP client for the PC end, so again no PC software required. While this may be overkill if all you need to do is transfer files, it has the advantage of allowing you to use the the single serial port concurrently for other data streams and application protocols such as Telnet. The disadvantage perhaps is that while Windows does support PPP it is buried within the dial-up networking and to be frank a pain to get working.
Very first step you have to do is ensure serial communication is working fine.
Send a byte continuously from mcu to PC and display it on some io console (for example: HyperTerminal, Dock light )
Receive a byte to mcu from PC and echo it back to PC.
Once you are sure that serial communication is working fine then select some file transfer protocol and implement it.
While you can select any of the available protocols or write your own protocol and implement it.
For purpose of discussion i select Xmodem protocol.
If you consider some other protocol you may stop reading answer here.
XMODEM is a simple file transfer protocol.
Refer http://web.mit.edu/6.115/www/amulet/xmodem.htm for detailed information.
You may implement Xmodem mcu side by reading protocol. Or may consider using open source also ( if available )
PC side i prefer to use HyperTerminal io console as it is compatible with Xmodem.
In HyperTerminal all that i have to do is configure settings and select file for transfer to mcu.
Now transfer any file to mcu using Xmodem protocol from PC.
What you do with received file in mcu is up to you : )
This may not be in the right location, so tell me and I'll move it.
I am a recent EE grad and I was hired to build a system that exists on a SoC with a simple 32-bit processor. The system basically monitors several external devices and performs some DSP on it, and then is supposed to send the results using a WiFi device (in my case I have the ESP8266 using UDP) to an email server for logging/notification.
I have been trying to find a library that I can use, but my uC can only program in C and I have it set up for UDP, and everything is in C++ using some other protocol, or something else completely.
I am great at DSP, decent at SoC's and uC's, but when it come to this email server communication thing I am at a loss.
I have successfully configured everything for the sensors, the datapath, the DSP, and connected the system to my WiFi via UDP, but I have yet to figure out how to send data to any servers.
Could someone help me understand how I should go about this?
I have looked into some simple SMTP commands such as HELO, MAIL, RCPT, DATA, etc. but I cannot understand how I actually should implement them in my code.
When I send out the WiFi data via UDP what type of data do I send and how do I format it? Do I need to send any other kind of flags? How should I expect the response? I also know the data has to be transformed into base 64 which is confusing me further.
I am also not super familiar with UDP to begin with, I have been using libraries that are part of the SoC's default library to connect to my WiFi.
I know these may either seem like obvious or stupid questions but it is were I no longer have any knowledge, and everything I find online doesn't make sense, or doesn't attempt to explain it, just gives a pre-made solution
I have found the RFC2821 but it doesn't get any clearer.
I know that's a lot but any help at all would be a lifesaver!
Since you are asking this question, I'm assuming that you are not booting and running an OS suitable for micro-controllers such as an embedded variant of Linux or such. If you were, you would simply be able to take advantage of possibly built in applications or other existing code.
But you don't mention having written an Ethernet stack, so are you using some other library or operating environment which might have some of the functionality needed for an implementation of SMTP?
If you don't and really do need to write your own SMTP client to run directly on the processor you are using, then you should be able to find plenty of examples of source code for this. A quick google search of How To Write an SMTP client showed a few articles with some example code. One article seems to be an exact hit, but you need to look at it further.
However, I would highly suggest just sitting down with a telnet client and connect to an SMTP server you are allowed to use and try the commands you need to just send a message. If you only need to send text, you don't need to get involved in MIME encoding or anything like that.
I am currently working with an embedded FOX G20 V board with an ATMEL AT91SAM9G20 processor. I am hoping to be able to establish a connection by ethernet between this board, and a linux machine. The protocol of communication is using the uIP library (smaller implementation of TCP/IP intended for embedded boards).
Anyway, I've downloaded the developpment kit offered by the processor, and it has countless examples of different types of communications, one of which includes a hello world program.
However, at this point, even with the example, I'm relitvely stuck. I am un sure which file of the hello world project it is I have to compile since there are many of them. Is it the main.c that is located in at91sam9g20-ek.zip\at91sam9g20-ek\packages\basic-emac-uip-helloworld-project-at91sam9g20-ek-iar.zip\basic-emac-uip-helloworld-project-at91sam9g20-ek\at91sam9g20-ek\basic-emac-uip-helloworld-project\ or is it another file?
The whole point is to get a communication established by the board and the remote host (in this case my Linux machine), and send it "hello world" through ethernet. I am guessing that the application in this case defines its register addresses in which the board will be able to receive the connection from the remote host (I may be wrong).
In any case, I am hoping to get help by any "experts" that are familier with the project that may guide me, or explain to me how exactly to build this application they have provided.
I'm not familiar with this board but according to this link the application is supposed to start a telnet server (on port 1000) and an http server. I suggest that you look at the output on the serial link (to get the IP of your board, let's assume 10.159.245.156 as in the example), and if you get what is expected then you can try to telnet to your board:
telnet 10.159.245.156 1000
The kit gives you project file for three toolchains (IAR 5.4, Keil and GNU). You'll have either to open the correct one depending on your toolchain (which one do you use?), or adapt if you use another one.
Edit: You apparently use the IAR toolchain, thus you need to open the *.eww file (for instance basic-emac-uip-helloworld-project.eww). This example only obtains an IP and displays statistics on the debug output (serial link?). There are other examples for a telnet or http server.
Moreover it's a detail but I think the emacs tag is irrelevant in your post. I think you confused EMAC (what is this?) and Emacs which is a popular text editor.
I have just managed to write my first windows driver (havent registered it yet- but i managed to get the things created!).
I wondered if someone can give me a high overview of how I could achieve the following:
I would like to write a driver which will implement some behaviour when a network packet is received by the computer, before windows does what it does with the packet, i'd like to take this data and output it to the console of a C or C++ program.
Lets assume I have a C/C++ program written, which has a console. How does the C/C++ program interact with the driver I wrote which is hooking the network activity? Is it simply some C code which calls my drivers, the function returns the data as an object and then I can use that object to display in the console?
Thank you in advance for any possible replies
You don't need a driver for this task. Use packet sniffer library like PCap (actually you'll need WinPCap). It's really simple to capture packets and print them to console.
Alternative way is raw socket. But desktop Windows (as opposite to Windows Server) limits raw socket functionality.
If you really want a driver, or have a requirement to manipulate or filter packets before they hit the windows network stack you need to look into filter drivers.
This filter driver can then expose a device file on which your user space application can then read/write. The windows DDK contains examples.
This question might sound fool, because I know there are bunch of frameworks that does it for you. What I want is actually get in touch with low level C API deeply and able to write a program that sits on computer and intercepts packets between local machine and outer spaces. I tried to figure it out by looking at open source code (i.e. tcpdump) but it's quite difficult for me to find out which file actually performs network sniffing. Any suggestions would be appreciated !
You have to use raw socket. Here's an example.
At least for what concern Linux and Unix like operating systems. I don't know about Windows.
If you're using a UNIX based system[*] then the simplest mechanism is libpcap, which is part of the tcpdump project.
Your process will need root privileges to be able to access the network interface (as would also be the case with raw sockets).
Usually you'll end up having to decode ethernet frames, IP headers, etc yourself, although for most protocols this isn't that hard.
[*] It is actually available for Win32 as well, but I've not used it under Windows myself.