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Problem using UART port with serial device

Honored Contributor II



My configuration: 

-Altera cycloneV socDevKit 

-Linux kernel : 3.9.0 and debian filesystem from this rocketboards project : 


I'm trying to communicate with a serial GPS module (4800 8N1) plugged on the UART mini USB port. But I can't read data from the device. 

It works fine when I use a PC with a terminal. I even disabled the login prompt in /etc/inittab to directly read data send from the device but nothing happend. 


Anyone have solution ? 

Maybe a driver problem or tty settings ? 

Use HPS USB port could be better ? 



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1 Reply
Honored Contributor II



since you're using Linux, is it possible that cooked mode makes problems? If you just open a /dev/ttyWhatver port, it is configured in cooked mode by default. That would explain why you cannot read: your OS buffers all input and holds it back until a termination character arrives, but probably your device does not send such a character. The "PC with a terminal" you mentioned probably uses raw mode by default. 


Info about raw/cooked modes: (

What helped me to solve that in C/C++ (I assume you want to solve the problem in a C/C++ program since you posted it here): (



Best regards,