UART4 not working - configuration kernel version 4.1.18

Hi,

I’m currently trying to configure and test UART4 on the BBB.
So I my point is to connect the two pins and try to communicate with them through minicom.
However I haven’t any response from the board.

for my dts i’m using this one :
https://github.com/victorporof/BeagleBone-SPI-UART/blob/master/BB-UART4-00A0.dts

for my configuration :
( for the kernel, I follow this tutoriel :
https://eewiki.net/display/linuxonarm/BeagleBone+Black
)

`

uname -a

Linux beagle01 4.1.18-bone20 #4 Fri Mar 18 15:16:19 CET 2016 armv7l GNU/Linux

lsb_release -da

No LSB modules are available.
Distributor ID: Debian
Description: Debian GNU/Linux 8.3 (jessie)
Release: 8.3
Codename: jessie

`

`

dmesg | grep tty

[ 0.000000] Kernel command line: console=ttyO0,115200n8 capemgr.enable_partno=BB-UART4 root=/dev/mmcblk0p1 ro rootfstype=ext4 rootwait
[ 0.000298] WARNING: Your ‘console=ttyO0’ has been replaced by ‘ttyS0’
[ 3.102953] 44e09000.serial: ttyS0 at MMIO 0x44e09000 (irq = 154, base_baud = 3000000) is a 8250
[ 3.903811] console [ttyS0] enabled
[ 6.705576] systemd[1]: Expecting device dev-ttyS0.device…
[ 7.174265] systemd[1]: Starting system-getty.slice.
[ 7.192955] systemd[1]: Created slice system-getty.slice.
[ 7.198476] systemd[1]: Starting system-serial\x2dgetty.slice.
[ 7.222958] systemd[1]: Created slice system-serial\x2dgetty.slice.
[ 1023.102502] 481aa000.serial: ttyS5 at MMIO 0x481aa000 (irq = 187, base_baud = 3000000) is a 8250

`

`

cat $SLOTS

0: PF---- -1
1: PF---- -1
2: PF---- -1
3: PF---- -1
4: P-O-L- 0 Override Board Name,00A0,Override Manuf,BB-UART4

`

`

ls -l /dev/ttyS*

crw------- 1 root tty 4, 64 Mar 22 2016 /dev/ttyS0
crw-rw---- 1 root dialout 4, 65 Sep 7 2015 /dev/ttyS1
crw-rw---- 1 root dialout 4, 66 Sep 7 2015 /dev/ttyS2
crw-rw---- 1 root dialout 4, 67 Sep 7 2015 /dev/ttyS3
crw-rw---- 1 root dialout 4, 68 Sep 7 2015 /dev/ttyS4
crw-rw---- 1 root dialout 4, 69 Mar 22 11:15 /dev/ttyS5

`

`

cat /boot/uEnv.txt

uname_r=4.1.18-bone20
optargs=capemgr.enable_partno=BB-UART4

`

So finally I shorted P9_11 and P9_13 of the BBB and I launch minicom :

`

minicom -b 9600 -o -D /dev/ttyS5

`
In addition, here is the configuration of the serial port setup for minicom

`

A - Serial Device : /dev/ttyS5
B - Lockfile Location : /var/lock
C - Callin Program :
D - Callout Program :
E - Bps/Par/Bits : 9600 8N1
F - Hardware Flow Control : No
G - Software Flow Control : No
`

So normally, after all, I sould see an echo on the minicom but nothing.
So I didn’t really understand why did I do wrong ?

Notes :
I don’t know if it is link but :

  • I find strange the fact that I configure UART4 but it is ttyS5 which is configure
  • The minicom stay offline

`

`
CTRL-A Z for help | 9600 8N1 | NOR | Minicom 2.7 | VT102 | Offline | ttyS5

`

`

So if anyone have an Idea.
thanks by advance
Regards
Vincent

Well you have the pin's for uart4, but you've utilized uart5.. (this
worked in 3.8.x as the uart# was wrong.)

In v4.1.x: use

target = <&uart4>;

for uart4...

Regards,

I have try that and it works. So now I had a better understanding of the uart dts
Thanks a lot.

Regards,

Vincent