Adafruit BBIO: Unable to export UART channel

Moderators: adafruit_support_bill, adafruit

Please be positive and constructive with your questions and comments.
Locked
User avatar
rivetta
 
Posts: 2
Joined: Thu May 14, 2015 8:29 am

Adafruit BBIO: Unable to export UART channel

Post by rivetta »

Hello,

I'm using ubuntu 14.04.2 and Adafruit BBIO library.

When i execute:

UART.setup("UART4")

i detect this error

RuntimeError: Unable to export UART channel.


this is the print of: dmesg | grep tty

[ 0.000000] Kernel command line: console=ttyO0,115200n8 quiet drm.debug=7 capemgr.enable_partno=BB-UART1,BB-UART2,BB-UART4 root=UUID=854463c0-6305-4e7b-b9e7-d2edbfa8b232 ro rootfstype=ext4 rootwait fixrtc quiet
[ 0.000426] WARNING: Your 'console=ttyO0' has been replaced by 'ttyS0'
[ 2.654234] 44e09000.serial: ttyS0 at MMIO 0x44e09000 (irq = 88, base_baud = 3000000) is a 8250
[ 2.671940] console [ttyS0] enabled
[ 2.673157] 48022000.serial: ttyS1 at MMIO 0x48022000 (irq = 89, base_baud = 3000000) is a 8250
[ 2.674056] 48024000.serial: ttyS2 at MMIO 0x48024000 (irq = 90, base_baud = 3000000) is a 8250
[ 2.674871] 481a8000.serial: ttyS4 at MMIO 0x481a8000 (irq = 61, base_baud = 3000000) is a 8250
[ 2.675645] 481aa000.serial: ttyS5 at MMIO 0x481aa000 (irq = 62, base_baud = 3000000) is a 8250


this is the print of: ls -l /dev/tty*

crw-rw---- 1 root root 5 May 14 15:19 /dev/ttyO0 -> ttyS0
crw-rw---- 1 root root 5 May 14 15:19 /dev/ttyO1 -> ttyS1
crw-rw---- 1 root root 5 May 14 15:19 /dev/ttyO2 -> ttyS2
crw-rw---- 1 root root 5 May 14 15:19 /dev/ttyO4 -> ttyS4
crw-rw---- 1 root root 5 May 14 15:19 /dev/ttyO5 -> ttyS5
crw-rw---- 1 root tty 4, 64 May 14 15:20 /dev/ttyS0
crw-rw---- 1 root dialout 4, 65 May 14 15:19 /dev/ttyS1
crw-rw---- 1 root dialout 4, 66 May 14 15:19 /dev/ttyS2
crw-rw---- 1 root dialout 4, 67 May 14 15:19 /dev/ttyS3
crw-rw---- 1 root dialout 4, 68 May 14 15:19 /dev/ttyS4

this is the print of: uEnv.txt

#Docs: http://elinux.org/Beagleboard:U-boot_pa ... layout_2.0

uname_r=3.14.37-ti-r57
#dtb=
cmdline=quiet

#In the event of edid real failures, uncomment this next line:
#cmdline=quiet video=HDMI-A-1:1024x768@60e

##Example
#cape_disable=capemgr.disable_partno=

optargs=quiet drm.debug=7 capemgr.enable_partno=BB-UART4

##enable BBB: eMMC Flasher:
#cmdline=init=/opt/scripts/tools/eMMC/init-eMMC-flasher-v3.sh

uuid=854463c0-6305-4e7b-b9e7-d2edbfa8b232

Thank you,

Alessio

User avatar
adafruit_support_mike
 
Posts: 67446
Joined: Thu Feb 11, 2010 2:51 pm

Re: Adafruit BBIO: Unable to export UART channel

Post by adafruit_support_mike »

Have you disabled the serial console in raspi-config?

User avatar
rivetta
 
Posts: 2
Joined: Thu May 14, 2015 8:29 am

Re: Adafruit BBIO: Unable to export UART channel

Post by rivetta »

I'm using a beaglebone black rev c.

Thanks

Alessio

User avatar
adafruit_support_mike
 
Posts: 67446
Joined: Thu Feb 11, 2010 2:51 pm

Re: Adafruit BBIO: Unable to export UART channel

Post by adafruit_support_mike »

Oh duh..

From the error messages, it looks like that UART is already being used by the serial console. Since it's already in use (by root, for a critical system function) you won't be able to do anything else with it.

I'm sure there's a way to disable the serial console, but don't know the BBB's incantation for it off the top of my head.

In practice, it would probably be easier to use one of the other existing UARTs.

User avatar
akamediasystem
 
Posts: 79
Joined: Tue Apr 30, 2013 1:38 pm

Re: Adafruit BBIO: Unable to export UART channel

Post by akamediasystem »

Hi, I've successfully used UART4 but unfortunately I don't know for sure what's going on with your device.

You might try temporarily trying to address another UART (UART2 is an easy one, IIRC) to see if it's a pin conflict (for example, I don't recall offhand which pins HDMI uses, and I know I've run into conflicts using SPI and some of the UARTs).

I notice in your dmesg that you're trying to use three UARTs at once - it might be worth trying to address one at a time, to see if there's an overlap between any UART pin assignments.

You might also try ensuring you're running the python code as root (at times, I has weird problems with Adafruit_BBIO when not root; now I sudo -i at the start of all my BBB adventures).

Sorry I don't have a for-sure solution; hope this helps!

AKA

Locked
Please be positive and constructive with your questions and comments.

Return to “Beagle Bone & Adafruit Beagle Bone products”