Problem to enable DCAN1 at BBB

[markus schiesser]

Hi out there,

hope someone can help me to activate the CAN Bus interface at Beaglebone Black. I describe shortly what I
have done so far...

Debain linux
cat /etc/debian_version
8.2

uname -a
Linux beaglebone 4.1.10-ti-r23 #1 SMP PREEMPT Fri Oct 16 23:55:32 UTC 2015 armv7l GNU/Linux

I downloaded the Device Tree Overlay from RobertCNelson
https://github.com/RobertCNelson/bb.org-overlays
followed instruction and installed it

I added the BB-CAN1 device (P9-24/26)
sh -c "echo 'BB-CAN1'> /sys/devices/platform/bone_capemgr/slots"

root@beaglebone:~# cat /sys/devices/platform/bone_capemgr/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-CAN1
 
 dmesg
[ 1266.197246] bone_capemgr bone_capemgr: part_number 'BB-CAN1', version 'N/A'
[ 1266.197290] bone_capemgr bone_capemgr: slot #4: override
[ 1266.197308] bone_capemgr bone_capemgr: Using override eeprom data at slot 4
[ 1266.197326] bone_capemgr bone_capemgr: slot #4: 'Override Board Name,00A0,Override Manuf,BB-CAN1'
[ 1266.208737] bone_capemgr bone_capemgr: slot #4: dtbo 'BB-CAN1-00A0.dtbo' loaded; overlay id #0
[ 1266.226715] CAN device driver interface
[ 1266.245068] c_can_platform 481d0000.can: c_can_platform device registered (regs=fa1d0000, irq=191)

Installed can-utils
# git clone git://gitorious.org/linux-can/can-utils.git

and load modules

modprobe can
modprobe can-dev
modprobe can-raw

now setting up interface
ip link set can0 up type can bitrate 125000 triple-sampling
ifconfig can0 up

show the interace
ifconfig can0

can0      Link encap:UNSPEC  HWaddr 00-00-00-00-00-00-00-00-00-00-00-00-00-00-00-00
          UP NOARP  MTU:16  Metric:1
          RX packets:3 errors:0 dropped:0 overruns:0 frame:0
          TX packets:0 errors:0 dropped:0 overruns:0 carrier:0
          collisions:0 txqueuelen:10
          RX bytes:24 (24.0 B)  TX bytes:0 (0.0 B)
          Interrupt:191
         
root@beaglebone:~# ip -d -s link show can0
3: can0: <NOARP,UP,LOWER_UP,ECHO> mtu 16 qdisc pfifo_fast state UP mode DEFAULT group default qlen 10
    link/can  promiscuity 0
    can <TRIPLE-SAMPLING> state ERROR-ACTIVE (berr-counter tx 0 rx 0) restart-ms 100
          bitrate 125000 sample-point 0.875
          tq 500 prop-seg 6 phase-seg1 7 phase-seg2 2 sjw 1
          c_can: tseg1 2..16 tseg2 1..8 sjw 1..4 brp 1..1024 brp-inc 1
          clock 24000000
          re-started bus-errors arbit-lost error-warn error-pass bus-off
          0          0          0          1          2          1
    RX: bytes  packets  errors  dropped overrun mcast
    4          0        0       0       0       0
    TX: bytes  packets  errors  dropped carrier collsns
    0          0        0       8       0       0

I attached to my canbus an embedded controller, sending constantly some bytes at a rate of 125kBit
on the BBB I start candump to monitor this traffic. No frames received

candump can0

At the same time I connected a raspberry Pi to the same canbus and received frames from the embedded
controller

pi@raspberrypi ~ $ candump can0
  can0  539   [1]  5A
  can0  539   [1]  5B
  can0  539   [1]  5C
  can0  539   [1]  5D

if I try to send some frames from the BBB it will fail es well

root@beaglebone:~# ip -d -s link show can0
3: can0: <NOARP,UP,LOWER_UP,ECHO> mtu 16 qdisc pfifo_fast state UP mode DEFAULT group default qlen 10
    link/can  promiscuity 0
    can <TRIPLE-SAMPLING> state ERROR-ACTIVE (berr-counter tx 0 rx 0) restart-ms 100
          bitrate 125000 sample-point 0.875
          tq 500 prop-seg 6 phase-seg1 7 phase-seg2 2 sjw 1
          c_can: tseg1 2..16 tseg2 1..8 sjw 1..4 brp 1..1024 brp-inc 1
          clock 24000000
          re-started bus-errors arbit-lost error-warn error-pass bus-off
          5          0          0          6          10         6
    RX: bytes  packets  errors  dropped overrun mcast
    216        27       0       0       0       0
    TX: bytes  packets  errors  dropped carrier collsns
    0          0        0       13      0       0

written packages are dropped and the error-pass, bus-off counter increase since the CANBus gets
restarted. During startup the CANBus receives some frames.


cat /sys/kernel/debug/pinctrl/44e10800.pinmux/pinmux-pins | grep can
pin 96 (44e10980.0): 481d0000.can (GPIO UNCLAIMED) function pinmux_dcan1_pins group pinmux_dcan1_pins
pin 97 (44e10984.0): 481d0000.can (GPIO UNCLAIMED) function pinmux_dcan1_pins group pinmux_dcan1_pins

cat /sys/kernel/debug/pinctrl/44e10800.pinmux/pingroups

group: pinmux_dcan1_pins
pin 97 (44e10984.0)
pin 96 (44e10980.0)

From my point of view everything looks fine, cable connections etc. I checked by oscilloscope as
CANBus drive I used SN65HVD230D. Correct signal is connected to DCAN1_RX P9_26. If is send CANFrames
I cannot measure anything at P9_24.
Has anyone further ideas to get to the bottom of the problem. Anyone has such a config running
successfully?

Thanks for your hints

markus

[Benoit Perron]

Hi there,

 I am in exactle the same position as you. I triesd with 4.1.5-ti-r10 with my own dto as well as the one from the debian image, and tried again last night with the latest release (with the universal-io dtbo) and couldn't get any thing to work.

I have tried on 3 different boards (2 revC and 1 revA). One of my problem is that I don't have any known working canbus device to test against.

even if I don't use a transceiver chip, I should be able to see a signal on the scope comming from the p9.26 pin right?

The loopback mode and vcan drivers are all working perfectly.

[markus schiesser]

I'am back again...

I have to give a update...
I was digging for quite a while into the issue and didn't had any solution. Therefor I moved to official cape which worked out of the box. I bought the BeagleBone Serial Cape CBB-Serial form http://www.logicsupply.com/cbb-serial/#specs
After having a working board it was easy to debug my setup. It was a simple cable issue.

Here the correct cabling between CAN driver and BBB

BBB                             SN65HVD230D
DCAN1-Rx (P9.24)  ->    R(4)
DCAN1-Tx(R9-25)   ->    D(1)
GND                      ->   GND(2)
VCC 3.3V              ->    Vcc(3)
NC                        ->    (5)
                             ->    CANL(6)
                             ->    CANH(7)
GND                      ->    RS(8)

Hope it helps someone getting CAN Bus up an running at the BBB with less pain

markus