Need help to access serial ports in Beagle Board-xm-rev c

GoogleGroups
1

Hi,
I am using ,
Beagle Board- xm -rev C

File System Details:
#uname -a
Linux arm 3.6.2-x3 #1 SMP Sat Oct 13 10:20:13 UTC 2012 armv7l armv7l armv7l GNU/Linux
And, its ubuntu-12.10-r1-minimal-armhf-2012-10-19

I am trying to access, the serial ports through ‘C’ code. The following is the part of the code.

fd0=open("/dev/ttyS1",0,O_RDWR);
ret = write(fd0,“HiS1”,4)

  1. the open call get success.
  2. Write call got failed with error as, “Write Error. Errno:9 Str;Bad file descriptor”

I tried, ttyS2/3/4 also.

Can anyone help?

Thanks,

2

Well, the uarts are "ttyOx" not ttySx...

Regards,

3

thanks, But, initailly I tried with, “/dev/tty01” only. I tried from 1-3 also. Same error. So, I give it a try with ttySx.

Thanks Robert, :slight_smile:

4

Well, that should be an O as in Omap, not 0 as in zero as you typed above…

5

omg, my bad. Now at work.I will try tonight and post the result. Thanks a lot Robert :slight_smile:

6

I tried with the “/dev/ttyO1” , [ replaced 1 with 2,3,4 also ] . No luck.

Board : Beagle Board xm - rev C
uname -a : Linux arm 3.6.2-x3 #1 SMP Sat Oct 13 10:20:13 UTC 2012 armv7l armv7l armv7l GNU/Linux
file a.out: a.out: ELF 32-bit LSB executable, ARM, version 1 (SYSV), dynamically linked (uses shared libs), for GNU/Linux 2.6.31, BuildID[sha1]=0x82214316c6d4fccb7121e6c6fa1b39b4876e20cd, not stripped

Src:

7

        Well, that should be an O as in Omap, not 0 as in zero as you typed above...

I tried with the "/dev/ttyO1" , [ replaced 1 with 2,3,4 also ] . No luck.

*Board : *Beagle Board xm - rev C
*uname -a :* Linux arm 3.6.2-x3 #1 SMP Sat Oct 13 10:20:13 UTC 2012 armv7l armv7l armv7l GNU/Linux
*file a.out:* a.out: ELF 32-bit LSB executable, ARM, version 1 (SYSV), dynamically linked (uses shared libs), for GNU/Linux 2.6.31,
BuildID[sha1]=0x82214316c6d4fccb7121e6c6fa1b39b4876e20cd, not stripped

*Src:
###########################################################################################*
/#include<stdio.h>
#include<string.h>
#include<sys/types.h>
#include<sys/stat.h>
#include<fcntl.h>
#include<errno.h>

int main()
{
         int fd0=0;
         int ret=0;
         errno = 0;
         fd0=open("/dev/ttyO1",0);

This should probably read
     fd0=open("/dev/ttyO1",O_RDRW);

With a '0' as the second parameter, you are opening the device but not asking
for permission to either read or write from it.

8

hey, Thanks Gary . Its working now for all 0,1,2,3. Sorry for disturbing mailing list for this silly thing.

9

Hi, please try this to active your serial port:

opkg install kernel-module-usbserial
opkg install kernel-module-ch341 (or pl2303 or ft232)
echo ch341 >> /etc/modules
echo usbserial >> /etc/modules
update-modules
depmod -a
modprobe ch341

after that, you can use it such as ttyUSB0
Good luck.