I have an Ada program that communicates with an Intellibox Basic(a box that allows you to control trains) that is connected via USB.
Under Windows, I had to install a specific Serial driver (CP210x USB to UART Bridge VCP). With that driver I can communicate perfectly with the box. That means sending commands to the box.
Under Linux I'm communicating via /dev/ttyusb0 and I'm able to get messages from the box, but I can't send commands to the box. Nothing happens. I don't get an error or something.
Is the behavior of GNAT.SerialCommunication differently on Linux ? The program is the same. Do I have to setup certain things to get it to work on Linux ?
For example: A typical 2-byte command has the Command as the first Byte and the CRC check as the second one.
I had trouble with Serial_Communication at some point, where it turned out to be a problem with hardware-handshake being enabled in Linux. It's hard-coded in g-sercom.adb, look for "CRTSCTS". If your Intellibox does not use hardware handshake, Write() will block.
I believe I solved it by removing the CRTSCTS mask from the flags.
Related
I'm debugging an embedded application that runs in a Linux environment on a remote target. The only usable interface to the board is a single serial interface. Right now that's hooked up /bin/sh on init. I'm connecting with minicom, (re-)loading my application with lrzsz, and using printfs to get the job done.
I'd like to use gdbserver for more fine-grained debugging, but connectivity seems like a problem. Normally I'd connect over ethernet, but that's not available on this hardware. I understand gdbserver can run on a serial line, but right now my one comm port belongs to the shell.
Is there a good way to work around this restriction? Ideally I'd like to be able to run gdbserver and get back to a shell when I'm finished. I've tried starting gdbserver from the shell using the one available serial interface (/dev/ttyS0), then quitting minicom and starting GDB on my host, but it's messy & doesn't appear to work (even after setting remotebaud appropriately). Should that work? What's the sane thing to do in this situation?
How about the old-school solution? Use PPP to run IP networking over your serial line. You can then ssh (or even telnet) to your board, and connect to gdb at the same time. Given your circumstance, I'd recommend starting pppd manually to reduce the risk of locking yourself out through misconfiguration. The LDP link dates from 2000, but contains a lot of debugging advice.
I'm writing a library that interfaces to a Full Speed USB device using libusb. It seens to be working fine, but when I run the code inside GDB or Valgrind, I see in Wireshark that there are CLEAR_TT_BUFFER commands being send to the USB hub (I presume it's the internal one, since I have the device directly attached to the PC), and some packets seem to be lost (this shouldn't happen, as I'm using bulk transfer).
So the question is, what (under which conditions) is issuing those commands, and how do I prevent/detect them?
I am working with a SOM mounted on a carrier board running Ubuntu 14.04 with the generic 3.13 kernel.
While testing out the peripherals, I hit a problem with serial communication.
Basically, I can transmit data from the custom platform to an external Linux machine, but I can not properly receive data from the external Linux machine to the custom platform.
Through my research I have messed with all sorts of BIOS settings, baud rates, hardware flow control, parity, etc. Nothing has worked. Most info I have found online just says "Make sure your baud rates and other settings match", and they do. It is not my first time working with Linux serial ports. But it is my first time encountering a problem like this.
Does anyone have any suggestions, recommendations, or has anyone ever seen an issue like this before?
More info: We are running a quad-core Intel Atom micro with a custom serial breakout interface. The serial port is at /dev/ttyS0.
EDIT (clarification):
If I set up a session in Picocom or Minicom, I can send characters from our custom platform (running Ubuntu 14.04) to another Linux PC (also running Ubuntu 14.04). However, if I try to send characters from the Linux PC to our custom board, I sometimes get nothing, and other times get unrecognized characters (they show up as bubbles with question marks in them).
I can also simply echo a string to /dev/ttyS0 on the custom platform and receive it on the Linux PC. I just can't get it to work the other way around.
I'm a developing a Windows application for communication with meter devices over serial modems. Some of the devices using half duplex communication. For that reason I'm setting the Windows RtsControl parameter to RTS_CONTROL_TOGGLE, which enables an automatic switch of the RTS line state.
Now I want to port this application to Linux. Is there an function to enable an equivalent feature to the RTS_CONTROL_TOGGLE parameter on a Linux OS?
If there is no such function, does a workaround exist to enable a similar behavior?
I'm assuming you're in user space - so you'll probably end up using an IOCTL. If you're moving from Windows to Linux for serial control I recommend reading The POSIX Serial Programing Guide. The link I give is an example for setting serial values with an IOCTL, you would need to change it to use TIOCM_RTS, TIOCM_CTS, but it gives the right idea.
What is the best way to setup one Linux box to listen on its serial port for incoming connections? I've done a lot of googling but I can't find the right combination of commands to actually get them to talk!
My main objective is to provide a serial interface to running instances of kvm/qemu VMs. They currently only have a VNC interface (they are on headless servers, no X). I can get the VM to create a serial device by starting it with the -serial file: flag, but how to talk to it, is a whole other problem. Both boxes are running Ubuntu 8.04.
The Linux Serial HOWTO has a lot of detailed information about serial communication in general. The more-specific Linux Remote Serial Console HOWTO is what you're really looking for if you want to be able to log into your virtualized systems using the serial port as if you were at the console. As Hein indicated, you'll need a null modem cable and need to run minicom on the remote terminal.
The Linux console is used in two ways, each of which must be configured separately for serial use. You can configure the kernel to copy its messages over the serial port, which is occasionally interesting for watching the system boot and nearly indispensable if you're doing kernel debugging. (This requires kernel support and updating the boot parameters so the kernel knows you want serial output; see chapter 5 of the second howto.) You're probably more interested in logging in via the serial port, which requires running getty on the serial port after boot (just like your system already runs getty on the virtual terminals after boot), which is described in detail in chapter 6 of the howto.
I assume you connect the two serial ports using a "null modem" cable.
Use a program like minicom to talk to remote system -- you probably need to set up the communication parameters and possibly turn off hardware flow control (if your cable doesn't have the flow-control lines connected).
Say you're doing this on /dev/tty1.
in the shell
chown *youruser* /dev/tty1
then in a Perl script called example.pl
open PORT, "</dev/tty1" || die "Can't open port: $!";
while (defined ($_ = <PORT>))
{
do_something($_);
}
close PORT;
Obviously there is more to do if you want this to start automatically, and respawn on error, and so on. But the basic idea is to read from the serial port like a file.