I'm working on an i/o project where I have a microcontroller that communicates with my mac through a serial terminal using the screen command in Terminal.app
For example, to open the connection I type "screen /dev/tty.usbserial-number 115200" and then can type commands/data that are sent to the microcontroller
I would like to write a shell script, applescript, c program, or something simple like that that initiates the connection, sends the number "16" and then closes the connection
Thanks
Why do you need to use 'screen'? Can't you just do something like "stty -F 115200 /dev/ttyS0 ; echo '16' >/dev/ttyS0" ? Is there something specific about the setup?
Related
I have a application that launches xterm and dumps uart logs. I am able to see it launch and dump the logs in the GUI. However, Using a remote session I want the xterm output to be running as a background process somewhere so that I can switch back and forth within a single terminal.
Using GUI
Using remote terminal (SSH)
$ xterm
xterm: Xt error: Can't open display: :0
I tried to do something like, but failed to work -
alias xterm="/bin/bash -c"
I don't want to have X forwarding and launch a window on my local machine as well.
If you just need the logs, you most likely don't need an X server or xterm.
You can simply run the target command itself. From your screenshot it looks like the command might be telnet 127.0.0.1 <port_number>. You can find it from the script that your application launches, or with ps -ef when it's running. If it's an UART, then you can also use minicom or socat to connect directly to serial port without any extra programs. This way, you don't even need telnet.
You can combine this command with either screen or tmux so that it's running in the background and you can switch to it from any terminal or console. Just run screen with no arguments, then run the command on virtual screen. Detach with CTRL-a d, and your command will continue to run in the background ready for you to reconnect to it at any time with screen -r.
Moreover, screen can also connect to serial port directly so you get two for the price of one.
The thing with xterm is that it will not write the logs anywhere except in the graphics buffer, and even there it will be only as flashing pixels which is not suitable for any processing. If you insist on going that way, you have several options:
Change the script that application runs (might not be possible depending on your situation)
Replace /usr/bin/xterm with your dummy script that just runs bash instead of xterm, and redirects the output to a file (ugly, but you could probably avoid breaking other applications by changing PATH and putting it somewhere else). In your script, you can use bash's redirection features such as >, or pipe output to tee.
Start a VNC server in the background and set the DISPLAY environment variable when you run your application to the number of virtual screen. In this case, any windows from application will open on VNC virtual screen and you can connect to it as you please.
Use xvfb as a dummy X server and combine it with xterm logging, etc.
Solution 1: Fake xterm on X11-less systems
You can also create a wrapper script that replaces xterm with another function. Test this out on a laptop with X11:
$ function xterm {
echo "hello $#"
}
$ xterm world 1
hello world 1
$ export -f xterm
$ /bin/xterm # opens a new xterm session
$ xterm world 2 # commands executed in second terminal
hello world 2
This means that you've replaced the command xterm for a function in all of the child processes.
Now, if you already know that your script will work in a terminal without xterm, you could create a function that accepts all of the parameters and executes it. No need for complicated screen stuff or replacing /usr/bin/xterm.
Solution 2: Dump UART data for the winz
If you want to save all of the uart data into a file, this is easily fixed by creating a screen session and a log file. Below the command will create a session named myscreensessionname that listens on the serial connection /dev/ttyUSB0 and writes its data to /home/$USER/myscreensessionname.log.
$ screen -dmS myscreensessionname -L -Logfile /home/$USER \
/myscreensessionname.log /dev/ttyUSB0 115200
Note that if you're going to use multiple screen sessions, you might want to use serial ids instead of /dev/ttyUSB0. You can identify the connections with udevadmin as follows.
$ udevadm info --name=/dev/ttyUSB0 | grep 'by-id'
S: serial/by-id/usb-FTDI_TTL232R-3V3_FTBDBIQ7-if00-port0
E: DEVLINKS=/dev/serial/by-id/usb-FTDI_TTL232R-3V3_FTBDBIQ7-if00-port0 /dev/serial/by-path/pci-0000:00:14.0-usb-0:4.4.4.1:1.0-port0
Here, instead of /dev/ttyUSB0, I would make use of /dev/serial/by-id/usb-FTDI_TTL232R-3V3_FTBDBIQ7-if00-port0.
EDIT:
You can attach the screen session with the following command. Once in the screen session, press crtl+a, and press d to detach.
$ screen -Dr myscreensessionname
To view all of your screen sessions:
$ screen -list
There is a screen on:
2382.myscreensessionname (04/02/2021 10:32:07 PM) (Attached)
1 Socket in /run/screen/S-user.
I have a very limited list of software that I can install on an (IOT edge) device. I have minicom and chat commands (in addition to standard commands like echo and cat), and need to write to a serial device a command and read the response.
The device in question is a modem, and I need to run AT commands on it. If using minicom and setting up the menu etc. I can run these commands normally, and get the output. The problem is that I have around a thousand of these devices, so setup and data logging needs to be automated.
So within these parameters is there a way to run minicom and capture the output without any interactive elements? I have tried
minicom -S scriptfile -C outfile
where scriptfile (for now) contains following:
sleep 1
send "AT"
This seems to ignore the sleep command, and outfile is created, but is left empty. Also what would I need to add to the command that it wouldn't open a session or interactive element?
I have set up my Arduino so when I send a "0" via the serial monitor, a stepper motor turns a given amount.
I want to include this in a bash script, but I can only get this to work when the arduino serial monitor is open and entering echo 0 > /dev/tty.usbserial641 in bash. I assume this is because serial monitor is opening the connection for me.
In my struggle to open the connection in bash (without serial monitor open) I have tried all manner of options with stty -f /dev/tty.usbserial641 and have also tried connecting reset to ground with a 10uF capacitor.
Can any help me open the connection in bash without the use of arduino serial monitor?
System:
Arduino Uno rev3
OS X 10.8.4
Many thanks,
hcaw
Do the commands below work for you.
# stty -F /dev/ttyUSB0 9600 cs8 -cstopb
# sleep 0.1
# echo "0" > /dev/ttyUSB0
There is a difference between the value 0 and the ascii char 0 (48). Which one you trying to send, and which one are you trying to receive?
If you want to read the port from the terminal you can do it like this
head -n 1 /dev/ttyUSB0 //the number after n is how many lines you want to read
As a last note, I am a fan of pySerial. I would much rather write an interface in python than shell scripts.
I found a great binary written in C that solves my problem called Arduino-serial. Here's the link.
I hope this helps people with similar problems!
I am newbie in Linux, sorry if the question sounds too easy.
I have some communication with the board.
what i do first is:
enable the usb and gsm driver and cat "/dev/ttyUSB0 &"
afterwards, I send some AT commands and automatically get replies like "OK" and so on.
What I want is to able to READ this output using bash scripts, or any other possible ways
Thx
You can use screen command to read and write to the GSM. for eg. execute the command sudo screen /dev/ttyUSB0 , it will open a new screen their you can send data and see received data.
Is it possible to set the baud rate for Macs in a terminal? If yes, how to set the baud rate in terminal through the terminal?
I am trying to talk to the Mac using an Arduino (open source microcontroller), an XBee (wireless communicator) to type in the terminal through the serial monitor. The only problem I am having is the baud rate of the serial monitor and terminal are different. I can easily change the baud rate for the serial monitor in the Arduino, but I do not know what the baud rate is for the terminal in Mac.
On Mac OS, stty seemingly can only change terminal settings for an ongoing access.
It works to either:
Access the serial interface, e.g. cat /dev/cu.usbserial, the default settings will be used at first. On a different terminal use stty, e.g. stty -f /dev/cu.usbserial 230400 to set the baud rate, the settings of the terminal accessed before will change.
There is a small time window after executing stty, in which the access can be performed with the desired parameters, e.g. stty -f /dev/cu.usbserial 230400 & cat /dev/cu.usbserial executes stty, detaches it and then immediately performs the access to the serial device.
For one line command logging serial port /dev/tty.usbserial-X's output to cat.out and terminating the logging by pressing Ctrl+C, here is the solution: trap 'kill $(jobs -p)' SIGINT ; cat /dev/tty.usbserial-X | tee cat.out & stty -f /dev/tty.usbserial-X 115200. You can type Ctrl+C to terminate logging to cat.out. (edited)
This only seems to work for the /dev/cu.* device files. I don't know the difference from /dev/tty.* files.
Minicom is an excellent tool that does exactly what you're asking for. You can get it using apt on ubuntu but should check this Tutorial out for Mac.
Keep the serial reset issue in mind if you plan on sending data to the Arduino. see http://arduino.cc/playground/Main/DisablingAutoResetOnSerialConnection
stty 19200 or so.
Check man stty, you can set stop bits, speed, etc.
Surprised that no one mentioned picocom which could set higher bard rate up to 4000000.