Using COM0 as serial

Javier Hernandez

Hello,

I am trying to use COM0 as a regular serial port not a terminal. The kernel uses COM0 "dev/tty" as a console by default right? In this project I use the same COM port to talk to other devices in serial mode. How do I change COM0 from terminal mode to serial mode. I have try to close("dev/tty") and then open("dev/ttyS", O_RDWR) and I get an error opening the port.

Regards,

Javier

over 14 years ago

0 Javier Hernandez over 14 years ago

Intellectual 590 points

Can someone help me with this issue?

0 Norman Wong over 14 years ago in reply to Javier Hernandez

Guru 26430 points

Usually serial ports are numbered. Maybe try "/dev/ttyS0". That might not get your code running. Depends what you are trying to do. The easiest situation to deal with is one serial port for your console and another for your other device. It you are trying to use the same serial port for both console and the other device, that is more complicated. You should look at how kermit, xmodem, ymodem, zmodem, etc. handle the switch between console and other device.

0 Javier Hernandez over 14 years ago in reply to Norman Wong

Intellectual 590 points

That is what I thought. I open the device without any errors, but somehow the console still have a hold of it. Does that make sense?

0 Norman Wong over 14 years ago in reply to Javier Hernandez

Guru 26430 points

The console uses a program shell, probably "/bin/bash" attached to "/dev/ttyS0". I guess you could boot up without a console. You would have to invoke your program via some other means or another shell via telnet, putty, inittab script etc. Maybe you post a question of unhooking the console from "/dev/ttyS0" after boot.

0 Javier Hernandez over 14 years ago in reply to Norman Wong

Intellectual 590 points

That is a great idea I will post the question in this same forum.

Thanks a bunch.

Processors

Processors forum

Using COM0 as serial