Enabling UART on Beaglebone Black

user_4578043 0
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I'm having trouble getting UART enabled. I've gone through many different directions on how to enable and troubleshoot from updating the uEnv.txt file to updating the kernel. I've come to conclude that it may be an issue with using a different kernel than the instructions, but I'm not sure? I don't know very much about the Beaglebone and I'm still learning. Whenever I try to test UART by using Python and typing the following:

import Adafruit_BBIO.UART as UART

UART.setup("UART1")

I get the error: File "stdin", line 1, in module

RuntimeError: Unable to export UART channel.

I'm also starting to worry that I simply don't have capemgr. When I run the command :

ls sys/devices

I don't have capemgr listed.

I'm using the latest Debian Image : Jessie Debian 8.3 (2016-01-24)

the Kernel version I'm running is 4.1.17-ti-rt-r46.

and my DTC version is 1.4.1-g1e75ebc9

I would really appreciate any help. I've been wrestling with this issue for a few days now. Thank you!

uart beagleboard beagleboneblack microprocessors debian
4 Answers

You can change /boot/uEnv.txt First of all enable UARTS:

cape_disable=bone_capemgr.disable_partno=BB-BONELT-HDMI,BB-BONELT-HDMIN
cape_enable=bone_capemgr.enable_partno=BB-UART1,BB-UART2,BB-UART4,BB-UART5

Then don't forget to configure pinmux with appropriate dtbo's:

###Overide capes with eeprom
uboot_overlay_addr0=/lib/firmware/BB-UART1-00A0.dtbo
uboot_overlay_addr1=/lib/firmware/BB-UART2-00A0.dtbo
uboot_overlay_addr2=/lib/firmware/BB-UART4-00A0.dtbo
uboot_overlay_addr3=/lib/firmware/BB-UART5-00A0.dtbo
user_55667970

I already answered this HERE, but let me re-post it:

I can vouch for Debian 10 using this method:

I was able to enable all 4.5 UARTs automatically on boot-up. Unlike Debian 9 and older versions, the uEnv.txt is present in /boot/.

  1. Back up this file.

  2. Edit this file using sudo privileges:

$ sudo nano uEnv.txt

The final version for enabling all the 4.5 UARTs should look as follows:

#Docs: http://elinux.org/Beagleboard:U-boot_partitioning_layout_2.0

uname_r=4.19.94-ti-r42
#uuid=
#dtb=

###U-Boot Overlays###
###Documentation: http://elinux.org/Beagleboard:BeagleBoneBlack_Debian#U-Boot_Overlays
###Master Enable
enable_uboot_overlays=1
# UART 1
uboot_overlay_addr0=/lib/firmware/BB-UART1-00A0.dtbo
# UART 2
uboot_overlay_addr1=/lib/firmware/BB-UART2-00A0.dtbo
# UART 4
uboot_overlay_addr2=/lib/firmware/BB-UART4-00A0.dtbo
# UART 5
uboot_overlay_addr3=/lib/firmware/BB-UART5-00A0.dtbo
# UART 3 (only TX). Note that in "uboot_overlay_addrX", the X need not be = UART id
uboot_overlay_addr4=/lib/firmware/BB-UART3-00A0.dtbo

###
###Overide capes with eeprom
#uboot_overlay_addr0=/lib/firmware/<file0>.dtbo
#uboot_overlay_addr1=/lib/firmware/<file1>.dtbo
#uboot_overlay_addr2=/lib/firmware/<file2>.dtbo
#uboot_overlay_addr3=/lib/firmware/<file3>.dtbo
###
###Additional custom capes
#uboot_overlay_addr4=/lib/firmware/<file4>.dtbo
#uboot_overlay_addr5=/lib/firmware/<file5>.dtbo
#uboot_overlay_addr6=/lib/firmware/<file6>.dtbo
#uboot_overlay_addr7=/lib/firmware/<file7>.dtbo
###
###Custom Cape
#dtb_overlay=/lib/firmware/<file8>.dtbo
###
###Disable auto loading of virtual capes (emmc/video/wireless/adc)
#disable_uboot_overlay_emmc=1
#disable_uboot_overlay_video=1
#disable_uboot_overlay_audio=1
#disable_uboot_overlay_wireless=1
#disable_uboot_overlay_adc=1
###
###PRUSS OPTIONS
###pru_rproc (4.14.x-ti kernel)
#uboot_overlay_pru=/lib/firmware/AM335X-PRU-RPROC-4-14-TI-00A0.dtbo
###pru_rproc (4.19.x-ti kernel)
uboot_overlay_pru=/lib/firmware/AM335X-PRU-RPROC-4-19-TI-00A0.dtbo
###pru_uio (4.14.x-ti, 4.19.x-ti & mainline/bone kernel)
#uboot_overlay_pru=/lib/firmware/AM335X-PRU-UIO-00A0.dtbo
###
###Cape Universal Enable
enable_uboot_cape_universal=1
###
###Debug: disable uboot autoload of Cape
#disable_uboot_overlay_addr0=1
#disable_uboot_overlay_addr1=1
#disable_uboot_overlay_addr2=1
#disable_uboot_overlay_addr3=1
###
###U-Boot fdt tweaks... (60000 = 384KB)
#uboot_fdt_buffer=0x60000
###U-Boot Overlays###

cmdline=coherent_pool=1M net.ifnames=0 lpj=1990656 rng_core.default_quality=100 quiet

#In the event of edid real failures, uncomment this next line:
#cmdline=coherent_pool=1M net.ifnames=0 lpj=1990656 rng_core.default_quality=100 quiet video=HDMI-A-1:1024x768@60e

##enable Generic eMMC Flasher:
##make sure, these tools are installed: dosfstools rsync
#cmdline=init=/opt/scripts/tools/eMMC/init-eMMC-flasher-v3.sh

#cape_enable=capemgr.enable_partno=BB-UART1,BB-UART2,BB-UART4,BB-UART5
  1. Save and reboot. Enjoy !
user_96257770
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