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I'm trying to use the CAN1 bus on the Beaglebone Black board (the pins at P9.24 and P9.26).

First I tried the config-pin commands to change the pinmux mode from its default state, and provided the following lines.

config-pin p9.24 can
config-pin p9.26 can
ip link set can1 up type can bitrate 1000000

Strangely, with a perfectly functional CAN device at the other end, no CAN packets could be sent or received. I even checked the signals with an oscilloscope and found no output signals at all. When I run the bus in the loopback mode the board had no problem in acknowledging packets from itself. So I figured something went wrong with the driver or the pinmux.

Next I tried Device Tree overlay and inserted the build-in dtbo filenames into the /boot/uEnv.txt file.

###Additional custom capes
uboot_overlay_addr4=/lib/firmware/BB-CAN0-00A0.dtbo
uboot_overlay_addr5=/lib/firmware/BB-CAN1-00A0.dtbo
#uboot_overlay_addr6=/lib/firmware/<file6>.dtbo
#uboot_overlay_addr7=/lib/firmware/<file7>.dtbo
###

I expected this will overlay the CAN0 & CAN1 pinmux modes after a reboot, but now queries on the pin configurations are giving weird errors.

debian@beaglebone:/lib/firmware$ config-pin -q p9.24
ERROR: open() for /sys/devices/platform/ocp/ocp:P9_24_pinmux/state failed, No such file or directory

The same messages for the other overlayed pins. Actually any config-pin commands don't work on these pins. (And of course the CAN bus is still not working)

I'm currently using the latest AM3358 Debian 10.3 (2020-04-06) SD IoT image, and packages seems to be all updated well. The image is flashed and no SD card is in. What am I missing?

Additional Info:

uname -a outputs

debian@beaglebone:/lib/firmware$ uname -a
Linux beaglebone 4.19.94-ti-r64 #1buster SMP PREEMPT Fri May 21 23:57:28 UTC 2021 armv7l GNU/Linux

version script

debian@beaglebone:/lib/firmware$ sudo /opt/scripts/tools/version.sh
git:/opt/scripts/:[e8ae28ccc34a177e9435a0d24cdf8421e081c19a]
eeprom:[A335BNLT00C00620BBBK11BC]
model:[TI_AM335x_BeagleBone_Black]
dogtag:[BeagleBoard.org Debian Buster IoT Image 2020-04-06]
bootloader:[eMMC-(default)]:[/dev/mmcblk1]:[U-Boot SPL 2019.04-00002-g07d5700e21 (Mar 06 2020 - 11:24:55 -0600)]:[location: dd MBR]
bootloader:[eMMC-(default)]:[/dev/mmcblk1]:[U-Boot 2019.04-00002-g07d5700e21]:[location: dd MBR]
UBOOT: Booted Device-Tree:[am335x-boneblack-uboot-univ.dts]
UBOOT: Loaded Overlay:[AM335X-PRU-RPROC-4-19-TI-00A0]
UBOOT: Loaded Overlay:[BB-ADC-00A0]
UBOOT: Loaded Overlay:[BB-BONE-eMMC1-01-00A0]
UBOOT: Loaded Overlay:[BB-CAN0-00A0]
UBOOT: Loaded Overlay:[BB-CAN1-00A0]
UBOOT: Loaded Overlay:[BB-HDMI-TDA998x-00A0]
kernel:[4.19.94-ti-r64]
nodejs:[v10.24.0]
/boot/uEnv.txt Settings:
uboot_overlay_options:[enable_uboot_overlays=1]
uboot_overlay_options:[uboot_overlay_addr4=/lib/firmware/BB-CAN0-00A0.dtbo]
uboot_overlay_options:[uboot_overlay_addr5=/lib/firmware/BB-CAN1-00A0.dtbo]
uboot_overlay_options:[uboot_overlay_pru=/lib/firmware/AM335X-PRU-RPROC-4-19-TI-00A0.dtbo]
uboot_overlay_options:[enable_uboot_cape_universal=1]
pkg check: to individually upgrade run: [sudo apt install --only-upgrade <pkg>]
pkg:[bb-cape-overlays]:[4.14.20210416.0-0~buster+20210416]
pkg:[bb-customizations]:[1.20210708.0-0~buster+20210708]
pkg:[bb-usb-gadgets]:[1.20200504.0-0~buster+20200504]
pkg:[bb-wl18xx-firmware]:[1.20210520.0-0~buster+20210520]
pkg:[kmod]:[26-1]
pkg:[librobotcontrol]:[1.0.5-git20200715.0-0~buster+20200716]
pkg:[firmware-ti-connectivity]:[20190717-2rcnee1~buster+20200305]
groups:[debian : debian adm kmem dialout cdrom floppy audio dip video plugdev users systemd-journal bluetooth netdev i2c gpio pwm eqep remoteproc admin spi iio docker tisdk weston-launch xenomai cloud9ide]
cmdline:[console=ttyO0,115200n8 bone_capemgr.uboot_capemgr_enabled=1 root=/dev/mmcblk1p1 ro rootfstype=ext4 rootwait coherent_pool=1M net.ifnames=0 lpj=1990656 rng_core.default_quality=100 quiet]
dmesg | grep remote
[   65.289088] remoteproc remoteproc0: wkup_m3 is available
[   65.320630] remoteproc remoteproc0: powering up wkup_m3
[   65.320664] remoteproc remoteproc0: Booting fw image am335x-pm-firmware.elf, size 217148
[   65.320951] remoteproc remoteproc0: remote processor wkup_m3 is now up
[   68.227786] remoteproc remoteproc1: 4a334000.pru is available
[   68.241566] remoteproc remoteproc2: 4a338000.pru is available
dmesg | grep pru
[   68.227786] remoteproc remoteproc1: 4a334000.pru is available
[   68.227985] pru-rproc 4a334000.pru: PRU rproc node pru@4a334000 probed successfully
[   68.241566] remoteproc remoteproc2: 4a338000.pru is available
[   68.241750] pru-rproc 4a338000.pru: PRU rproc node pru@4a338000 probed successfully
dmesg | grep pinctrl-single
[    0.943044] pinctrl-single 44e10800.pinmux: 142 pins, size 568
dmesg | grep gpio-of-helper
[    0.956633] gpio-of-helper ocp:cape-universal: ready
lsusb
Bus 001 Device 001: ID 1d6b:0002 Linux Foundation 2.0 root hub
END

dmesg for CAN

debian@beaglebone:/lib/firmware$ dmesg | grep can
[    1.205500] c_can_platform 481cc000.can: c_can_platform device registered (regs=3377e4b7, irq=42)
[    1.206878] c_can_platform 481d0000.can: c_can_platform device registered (regs=292aef38, irq=43)
[    1.422353] can: controller area network core (rev 20170425 abi 9)
[  992.007971] c_can_platform 481d0000.can can1: setting BTR=2701 BRPE=0000
[  992.016624] IPv6: ADDRCONF(NETDEV_UP): can1: link is not ready
[  992.017512] IPv6: ADDRCONF(NETDEV_CHANGE): can1: link becomes ready

The full uEnv.txt

debian@beaglebone:/lib/firmware$ cat /boot/uEnv.txt
#Docs: http://elinux.org/Beagleboard:U-boot_partitioning_layout_2.0

uname_r=4.19.94-ti-r64
#uuid=
#dtb=

###U-Boot Overlays###
###Documentation: http://elinux.org/Beagleboard:BeagleBoneBlack_Debian#U-Boot_Overlays
###Master Enable
enable_uboot_overlays=1
###
###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/BB-CAN0-00A0.dtbo
uboot_overlay_addr5=/lib/firmware/BB-CAN1-00A0.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
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0
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  1. I may suggest you to try "ask ubuntu" site. They are the same family with Debian

  2. Here goes a very random answer:
    "ERROR: open() for /sys/devices/platform/ocp/ocp:P9_24_pinmux/state failed, No such file or directory" suggests you need to "ls/which/where/find..." the directory and find where "state" is, or is not. And then, search related topics with that "ocp:P9_24_pinmux/state". It will lead you to the main question of how to setup pin_mux correct.

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2
  • 2
    \$\begingroup\$ Please use the comment system for discussion, answers should not contain discussion. \$\endgroup\$
    – Voltage Spike
    Aug 11 '21 at 22:51
  • \$\begingroup\$ I think ask ubuntu doesn't like questip´ons about Debian and Mint. \$\endgroup\$
    – Oskar Skog
    Aug 12 '21 at 6:23

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