BBB Wireless CAN1

General Discussion
1

Hi,
I am trying getting CAN bus to work on BBB Wireless for two days without any success. I am using a SN65HVD230D transciever and CAN1. I am following the procedure described by Canbus Python Debian 8.x – Thomas Wedemeyer. Here’s the output of uname -a:
Linux beaglebone 4.19.94-ti-r64 #1buster SMP PREEMPT Fri May 21 23:57:28 UTC 2021 armv7l GNU/Linux

cat /ID.txt:
BeagleBoard.org Debian Buster IoT Image 2020-04-06

The commands used to enable CAN1 are:
sudo config-pin p9.24 can
sudo config-pin p9.26 can
sudo ip link set can1 up type can bitrate 500000 restart-ms 100

I connect another device to the bus and start generating frames. When I do candump can1, nothing happens. Here’s the output of ip -det link show dev can1:

debian@beaglebone:~$ ip -det link show dev can1
3: can1: <NOARP,UP,LOWER_UP,ECHO> mtu 16 qdisc pfifo_fast state UP mode DEFAULT group default qlen 10
link/can promiscuity 0 minmtu 0 maxmtu 0
can state ERROR-PASSIVE (berr-counter tx 0 rx 127) restart-ms 100
bitrate 500000 sample-point 0.875
tq 125 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 24000000numtxqueues 1 numrxqueues 1 gso_max_size 65536 gso_max_segs 65535

can1: flags=193<UP,RUNNING,NOARP> mtu 16
unspec 00-00-00-00-00-00-00-00-00-00-00-00-00-00-00-00 txqueuelen 10 (UNSPEC)
RX packets 2 bytes 16 (16.0 B)
RX errors 0 dropped 0 overruns 0 frame 0
TX packets 0 bytes 0 (0.0 B)
TX errors 0 dropped 0 overruns 0 carrier 0 collisions 0
device interrupt 44

I have tested pins 24 and 26 and they toggle when used as GPIO; i also tested can1 in loopback mode, which works. I am lost here and can’t find what I am doing wrong; please help.

Thanks

2

Do you have at least one termination resistor across CAN_H and CAN_L? CAN communications cannot work without that. The bit rate must be the same for both too.

John Dammeyer

image001.jpg

3

Yes, I have a termination resistor (I’ve checked with two resistors also). The bit rate is the same.

With the scope I can see the other device transmitting on lines CANH and CANL; I can also see that the transciever has activity on the Rx pin, which is connected to p9.24.

4

I’ve used socketCAN with the BBB following direcitons similar to this page.

Have you by chance a second CAN device that you can use to monitor packets? I use a CANUSB from Lawicel, for example, as a method of ensuring that I’m working with a healthy CAN bus. I then bring in the Pi or BBB to sniff messages first before I worry about sending. My cape for the Beagle is a LogicSupply unit. I’ll plug it back in and see if I can get communications going. Because the sockets in Lazarus doesn’t support the socketCAN connection I’ve not yet used that with a Lazarus CANopen monitor program I wrote. It’s on the do list but currently project #42.

5

Does lsmod show a can module loaded?