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Cannot Read Data From Serial Port

Wim Huiskamp 3 years, 8 months ago. tanu1985 View Public Profile View LQ Blog View Review Entries View HCL Entries Find More Posts by tanu1985 Thread Tools Show Printable Version Email this Page Search this Thread Advanced If I add a time delay (time.sleep(3) for example) I get nothing. Sign in to comment Contact GitHub API Training Shop Blog About © 2016 GitHub, Inc. this contact form

Here's the code to set up the serial port from Perl: Code: $port = "/dev/ttyS0"; $baud = "115200"; $ob = Device::SerialPort->new ($port) || die "Can't Open $port: $!"; $ob->baudrate($baud) || die Password Linux - Enterprise This forum is for all items relating to using Linux in the Enterprise. And if it were being held, wouldn't that block the Perl program as well? I figure I'm not doing the conversion properly, since it's only one byte (and probably just 0xA5 being written as a negative), but I'm still getting all the same character. 03-19-2008

Any help would be much appreciated! Edit the file /boot/cmdline.txt, and delete the line console=ttyAMA0, 115200 kgdbooc=ttyAMA0, 115200 Edit the file /etc/inittab, comment the last sentence: #T0:23:respawn:/sbin/getty -L ttyAMA0 115200 vt100 Installed python-serial module In python2.7 environment, Is there any chance the output is being buffered and I wouldn't see anything until there were 256 or 512 or some other number of bytes? (I doubt it, but still, Tags can be used as keywords to find particular files of interest, or as a way to categorize your bookmarked postings.

That said it should then only block until your gps sends data, so I would make sure if it actually sends you data.

Post a comment on this answer The What about this idea then: Code: options.c_cflag &= ~CRTSCTS; The reason is that there's nothing in your code CLEARING c_cflag, and CRTSCTS may well be set when you request it from When I try to read it the code gets stuck. Search this Thread 10-12-2011, 05:28 PM #1 tanu1985 LQ Newbie Registered: Oct 2011 Posts: 5 Rep: Unable to read data from Serial port I am new to the linux.I

Eventually I'll be merging the send program and the listener. Product catalog Compare elements iteratively Why won't curl download this link when a browser will? posted by Ashwin Vanpal 12 Feb 2013 If you copy and paste the code and surround it with <<code>> tags it will be easier to read and people can http://stackoverflow.com/questions/28210113/unable-to-read-data-from-serial-port-in-c-on-ubuntu debug.

Then I gave the python environment, and used minicom, but the situation was same: As long as I typed any characters in minicom, the data could be sent to my laptop By continuing to use our site, you consent to our cookies. Could you give me an example ? FURTHER TESTS: I found that only after some data was sent by raspberry, it could receive data!

The following information are about what I've done: I installed a GPIO UART Shield with RS232 on my Raspberry Pi. you could check here Why did the best potions master have greasy hair? Here is the program:- #include #include #include #include #include #include #include #include using namespace std; int fd1; int fd2; string string_f; //char *buff,*buffer,*bufptr; And it returns the descriptor no matter how the read call went. –Some programmer dude Jan 29 '15 at 8:36 Couple of things.

A constant char, or a packet of some sort? weblink I've been playing around with inWaiting but I'm not sure if that the right track or not. –Kersakov Jan 3 '15 at 10:38 The function read() takes an optional more stack exchange communities company blog Stack Exchange Inbox Reputation and Badges sign up log in tour help Tour Start here for a quick overview of the site Help Center Detailed I have found out that it stops at the communication bit.

I am using this code, same source: var serialport = require("serialport"); var SerialPort = serialport.SerialPort; var sp = new SerialPort("/dev/ttyAMA0", { baudrate:9600, databits: 8, parity: 'none', stopBits: 1, flowControl: false, parser: Originally Posted by matsp If you still want to time-out on input, you can set the c_cc[VTIME] = n, where n is 0.1s periods that you are willing to way, e.g. Ideally I want the listener to block while waiting for a new byte from the serial port because it'll be one of two threads and it'll spend most of its time navigate here Even if I try to compare the char version of it to 0xA4, it doesn't match. 2) I included the commented out line: Code: fcntl(serfd, F_SETFL, 0); which, as I understand

posted by Stephen Paulger 12 Feb 2013 Comment on this question Please login to post comments. 2 Answers Erik Olieman 3 years, 9 months ago. Tags are public and visible to everyone. I have a sender program in C++ that sends commands to the device and I have a listener in C++ that is not receiving the data properly.

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This way you can easily keep track of topics that you're interested in. Developer does not see priority in git Development Workflow being followed Does f:x mean the same thing as f(x)? Can I hint the optimizer by giving the range of an integer? How to be Recommended to be a Sitecore MVP Count trailing truths What crime would be illegal to uncover in medieval Europe?

Download now × About Newsgroups, Newsreaders, and MATLAB Central What are newsgroups? Can clients learn their time zone on a network configured using RA? Your Answer draft saved draft discarded Sign up or log in Sign up using Google Sign up using Facebook Sign up using Email and Password Post as a guest Name his comment is here I'm using that as a test command because it's easy to hear the results.

I suppose that the line serialport = serial.Serial("/dev/ttyAMA0", 9600, timeout=0.5) closes and re-opens the serial port, flushing all the buffers. tjt Linux - Newbie 1 06-17-2004 01:21 AM All times are GMT -5. I think the "won't read" issue was because of a mistake I had in waiting for 10 bytes instead of 1 as well as needing to st the flags as you As I said, the Perl listener is working, but the C++ one is not.

Converting the weight of a potato into a letter grade Operator ASCII art Mimsy were the Borograves - why "mimsy" is an adjective? more hot questions question feed lang-c about us tour help blog chat data legal privacy policy work here advertising info mobile contact us feedback Technology Life / Arts Culture / Recreation Program to Write to Serial Port: #include /* Standard input/output definitions */ #include /* String function definitions */ #include /* UNIX standard function definitions */ #include /* I would have preferred to write this in just C, but I'll be forwarding code to another project that will be using it and they've said they need the libraries in

Also, have you tried flushing the port after the write to ensure the data is sent, as I've have problems with data being held in local data buffers until the port Thread To add a thread to your watch list, go to the thread page and click the "Add this thread to my watch list" link at the top of the page. To Write Data to Serial Port and 2. Can I hint the optimizer by giving the range of an integer?

See my answer on this question in your other thread: Your char input array has size 0. Spam Control Most newsgroup spam is filtered out by the MATLAB Central Newsreader. besides, i don't think it's the array thing that cause the problem –tristan Dec 6 '14 at 8:44 add a comment| 1 Answer 1 active oldest votes up vote 0 down It is not a regular file, so something wierd might be going on there. –bazza Feb 3 '15 at 7:48 P.s.

What are tags? I did following tests: In raspberry, I executed: import serial ser=serial.Serial("/dev/ttyAMA0",9600,timeout=1) ser.write("a") On my laptop, I could receive "a", and I sent "abcde" from my laptop. Since then I've been picking up what I can, which means I miss a LOT. When I sent that, I should have gotten an echo back confirming the device received it.