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Old 02-26-2014, 04:01 AM   #1
displace
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screen: Something keeps typing "AT+GCAP" to my terminal


I'm trying to use a usb-to-serial connection for an UART device on Mint linux. I setup the terminal by doing "# screen /dev/ttyADM0 115200". That's it, I get a nice serial connection to the device where I can interact with it. But when initializing the serial connection with the given command, something types in the "AT+GCAP" string to my terminal and hits newline/enter (sends the command over). This happens a couple of times only at the very beginning after starting the screen session, then it stops. I've also seen a few lines like "~x~" veing typed.

What is causing this behavior? I find it a nuisance since it interferes with the device I'm using.
 
Old 02-26-2014, 04:54 AM   #2
Doc CPU
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Hi there,

Quote:
Originally Posted by displace View Post
I'm trying to use a usb-to-serial connection for an UART device on Mint linux. I setup the terminal by doing "# screen /dev/ttyADM0 115200". That's it, I get a nice serial connection to the device where I can interact with it. But when initializing the serial connection with the given command, something types in the "AT+GCAP" string to my terminal and hits newline/enter (sends the command over). This happens a couple of times only at the very beginning after starting the screen session, then it stops.
it looks as though Ubuntu's/Mint's modem manager does that to check if there is a modem connected, and if so, to see what capabilities (e.g. fax, answering machine) it supports:
http://stackoverflow.com/questions/1...-modem-go-away
http://ubuntuforums.org/showthread.php?t=2056285

If you don't use actual modems, you might even try to uninstall the modem manager. I did so for my desktop PC - not because modem manager caused me trouble, but only because I was quite sure I didn't need it.

Quote:
Originally Posted by displace View Post
I've also seen a few lines like "~x~" veing typed.
That's the escape sequence to bring the modem from data mode into command mode.

[X] Doc CPU
 
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Old 02-26-2014, 05:50 AM   #3
displace
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Thank you, I believed it was the screen program that was misbehaving. This worked:
Quote:
# sudo stop modemmanager
# echo manual | sudo tee -a /etc/init/modemmanager.override
 
  


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