Enabling UART in new kernel 4.9 with debian OS 9.3

[salah...@gmail.com]

Hi all,

I'm using UART2 channel for serial communication in my bbb. I've modified following lines to enable uart2

##Example v4.1.x
#cape_disable=bone_capemgr.disable_partno=
#cape_enable=bone_capemgr.enable_partno=BB-UART2

 When I checked the ttyO signals, I could observe following ports

root@beaglebone:~# ls -l /dev/ttyO*

lrwxrwxrwx 1 root root 5 Jan 28 14:17 /dev/ttyO0 -> ttyS0

lrwxrwxrwx 1 root root 5 Jan 28 14:17 /dev/ttyO1 -> ttyS1

lrwxrwxrwx 1 root root 5 Jan 28 14:17 /dev/ttyO2 -> ttyS2

lrwxrwxrwx 1 root root 5 Jan 28 14:17 /dev/ttyO4 -> ttyS4

lrwxrwxrwx 1 root root 5 Jan 28 14:17 /dev/ttyO5 -> ttyS5

when I tested the uart in loopback mode, I couldn't receive any data at the channel.

After that, I've configured the pin manually as follows

config-pin P9_21 uart

config-pin P9_22 uart

And now, I'm getting data over uart. But, the ttyO signals are the same as follows.

In my understanding, ttyO should be like this

crw-rw---- 1 root tty     247, 0 Jan  1  2000 /dev/ttyO0

crw-rw---T 1 root dialout 247, 2 Jan  1  2000 /dev/ttyO2

 

Why it's showing this difference? And what's the actual method to enable uart?

My BBB has kernel 4.9 and debian OS 9.3