SK-TDA4VM: Does SK-TDA4VM board support CAN communication on linux A72? If so, how to enable it?

Arpan Dutta

Part Number: SK-TDA4VM

Hi,

I want to enable CAN communication between a Linux application on A72 core on SK-TDA4VM board and a PCAN CAN monitoring tool. Is this possible? if so what headers/pins do I need to look for?

I have a sample application which can send and receive messages over CAN over the can0 interface. But currently it says Cannot find device "can0" whenever the application tries to create the interface using sudo ip link set can0 type can bitrate 1000000. Attaching the source code for the sample CAN application.
/cfs-file/__key/communityserver-discussions-components-files/791/can_5F00_tx_5F00_rx.c

Kindly help.

Regards,
Arpan

over 2 years ago

0 Tarun Mukesh Puvvada over 2 years ago

TI__Guru 59306 points

Hello Arpan,

May i know which SDK version are you using ? and which CAN instance are you expecting to use ?

Regards

Tarun Mukesh

0 Arpan Dutta over 2 years ago in reply to Tarun Mukesh Puvvada

Prodigy 60 points

I have flashed the tisdk-default-image-j7-evm.tar.xz. And I am using ti-processor-sdk-rtos-j721e-evm-08_01_00_13 SDK.

And regarding the CAN instance, I am not sure. I have no preference as long as we can establish CAN communication between any linux app and PCAN tool.
So I think you can suggest better which CAN instance I can use.

Regards,
Arpan

0 Tarun Mukesh Puvvada over 2 years ago in reply to Arpan Dutta

TI__Guru 59306 points

Hello,

RTOS SDK is not compatible with SK Board. You are using linux sdk right ?

Regards

Tarun Mukesh

0 Arpan Dutta over 2 years ago in reply to Tarun Mukesh Puvvada

Prodigy 60 points

Yeah about that, I have just flashed the tisdk-default-image-j7-evm.tar.xz. The SDK I mentioned earlier is used for developing RTOS applications for other purposes. But in this case, you can ignore it as we are not doing anything with it.

We are just booting up the default image flashed and compiling the previously mentioned C application on board itself. I don't think I am using the Linux SDK for anything. Sorry for any confusion.

Regards,
Arpan

0 Tarun Mukesh Puvvada over 2 years ago in reply to Arpan Dutta

TI__Guru 59306 points

Hello,

Please expect delay in response due to public holiday in TI India.

Regards

Tarun Mukesh

0 Tarun Mukesh Puvvada over 2 years ago in reply to Tarun Mukesh Puvvada

TI__Guru 59306 points

Hello,

sorry i didn't get you clearly.Are you using Linux or RTOS ?

Which CAN instance are you using ? Is it Mcu domain or main domain ?

Regards

Tarun Mukesh

0 Arpan Dutta over 2 years ago in reply to Tarun Mukesh Puvvada

Prodigy 60 points

Hi,
Sorry for the confusion. Please ignore RTOS, it has nothing to do with the current scenario. I am just trying to run a CAN application on Linux on A72 core. Is it possible for this board?

And again, for the CAN instance, I am not sure if there is anyone that I can use with Linux. I think it would be better if you could suggest one that can be used.

Regards
Arpan

0 Tarun Mukesh Puvvada over 2 years ago in reply to Arpan Dutta

TI__Guru 59306 points

Hey Arpan,

Yes got it now.By default in Linux 9.1 we have MCU_MCAN0 and MCU_MCAN1 registered and enabled i believe.You can also refer https://e2e.ti.com/support/processors-group/processors/f/processors-forum/922168/faq-tda4vm-how-can-i-use-can-on-linux for other main domain can instance enabling.

Regards

Tarun Mukesh

0 Arpan Dutta over 2 years ago in reply to Tarun Mukesh Puvvada

Prodigy 60 points

Ok, so let's say that I download and flash this linux 9.1 image. Now, if I want to use MCU_MCAN0, what do I need to do?
I assume that I need to connect PCAN header with J1 MCU CAN0 pins. Can you provide some sample C application source code that can be compiled on board via gcc and used for CAN communication via MCU_MCAN0.

I have this sample application that can do the CAN communication, but not sure why it's not working.

Regards
Arpan

0 Tarun Mukesh Puvvada over 2 years ago in reply to Arpan Dutta

TI__Guru 59306 points

Hello,

Please look into faq https://e2e.ti.com/support/processors-group/processors/f/processors-forum/1132406/faq-sk-tda4vm-how-do-i-use-the-can-bus-headers-on-sk-tda4vm-using-edge-ai-sdk

I feel the above one explains your query to the point.

Regards

Tarun Mukesh

0 Arpan Dutta over 2 years ago in reply to Tarun Mukesh Puvvada

Prodigy 60 points

Hi,
I looked into the ticket you shared. According to the thread, the CAN interface is already enabled by default and we can directly test the CAN functionality.

The Edge AI SDK's prebuilt SD card image comes packaged with the same Linux driver for CAN as used in PSDK Linux. The CAN bus can be enabled and used as documented here: https://software-dl.ti.com/jacinto7/esd/processor-sdk-linux-jacinto7/08_02_00_03/exports/docs/linux/Foundational_Components/Kernel/Kernel_Drivers/MCAN.html

Linux discovers the CAN bus instances with the following names:

can0=J1=MCU_CAN0
can1=J5=CAN0
can2=J6=CAN5
can3=J2=CAN9

The header pins are defined like so (taken from SK userguide https://www.ti.com/lit/ug/spruj21b/spruj21b.pdf?ts=1651850889758&ref_url=https%253A%252F%252Fwww.google.com%252F):

To test CAN driver, we can do a loopback by connecting two CAN bus on SK board, then running the following commands:

root@j721e-eaik:~# ip link set can0 type can bitrate 500000
root@j721e-eaik:~# ip link set can1 type can bitrate 500000
root@j721e-eaik:~#
root@j721e-eaik:~#
root@j721e-eaik:~#
root@j721e-eaik:~# ip link set up can0
root@j721e-eaik:~# ip link set up can1
root@j721e-eaik:~#
root@j721e-eaik:~#
root@j721e-eaik:~# candump can0 &
[2] 1220
root@j721e-eaik:~# cansend can1 123#1122334455667788
can0 123 [8] 11 22 33 44 55 66 77 88
root@j721e-eaik:~#

Regards,

Takuma

But when I give the command:
ip link set can0 type can bitrate 500000

I get the following as output:
Cannot find device "can0".

Extra info:
I have connected my PCAN headers with J1 MCU CAN0 pins.
And here is the boot logs for the latest run: /cfs-file/__key/communityserver-discussions-components-files/791/5076.boot.log

Regards
Arpan

0 Tarun Mukesh Puvvada over 2 years ago in reply to Arpan Dutta

TI__Guru 59306 points

Hi Arpan,

root@tda4vm-sk:/opt/edgeai-gst-apps# dmesg | grep can
[    0.351581] HugeTLB: 0 KiB vmemmap can be freed for a 1.00 GiB page
[    0.364918] HugeTLB: 0 KiB vmemmap can be freed for a 32.0 MiB page
[    0.378253] HugeTLB: 0 KiB vmemmap can be freed for a 2.00 MiB page
[    0.391588] HugeTLB: 0 KiB vmemmap can be freed for a 64.0 KiB page

None of the CAN node got registered.

I am assigning to the expert on edge AI SDK.

Regards

Tarun Mukesh

0 Takuma Fujiwara over 2 years ago in reply to Tarun Mukesh Puvvada

TI__Guru 58783 points

Hi Arpan,

I just tried with the ether image for SK-TDA4VM that can be downloaded here: https://www.ti.com/tool/download/PROCESSOR-SDK-LINUX-SK-TDA4VM/08.01.00.02. It seems CAN is enabled by default in this image based on the logs from ifconfig -a:

root@j7-evm:/opt/edge_ai_apps# ifconfig -a
can0: flags=128<NOARP>  mtu 16  metric 1
        unspec 00-00-00-00-00-00-00-00-00-00-00-00-00-00-00-00  txqueuelen 10  (UNSPEC)
        RX packets 0  bytes 0 (0.0 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 20

can1: flags=128<NOARP>  mtu 16  metric 1
        unspec 00-00-00-00-00-00-00-00-00-00-00-00-00-00-00-00  txqueuelen 10  (UNSPEC)
        RX packets 0  bytes 0 (0.0 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 42

can2: flags=128<NOARP>  mtu 16  metric 1
        unspec 00-00-00-00-00-00-00-00-00-00-00-00-00-00-00-00  txqueuelen 10  (UNSPEC)
        RX packets 0  bytes 0 (0.0 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

can3: flags=128<NOARP>  mtu 16  metric 1
        unspec 00-00-00-00-00-00-00-00-00-00-00-00-00-00-00-00  txqueuelen 10  (UNSPEC)
        RX packets 0  bytes 0 (0.0 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 46

eth0: flags=4099<UP,BROADCAST,MULTICAST>  mtu 1500  metric 1
        ether 34:08:e1:56:2d:b4  txqueuelen 1000  (Ethernet)
        RX packets 0  bytes 0 (0.0 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

lo: flags=73<UP,LOOPBACK,RUNNING>  mtu 65536  metric 1
        inet 127.0.0.1  netmask 255.0.0.0
        inet6 ::1  prefixlen 128  scopeid 0x10<host>
        loop  txqueuelen 1000  (Local Loopback)
        RX packets 82  bytes 6220 (6.0 KiB)
        RX errors 0  dropped 0  overruns 0  frame 0
        TX packets 82  bytes 6220 (6.0 KiB)
        TX errors 0  dropped 0 overruns 0  carrier 0  collisions 0

root@j7-evm:/opt/edge_ai_apps#

My recommendation would be to try this image out. It could be that the image you are using is using a different device tree that only enables a subset of the SK board peripherals since the image was mainly developed for the larger EVM board instead of the SK board.

To give some extra information, CAN interfaces need to be defined in the device tree like this: https://git.ti.com/cgit/ti-linux-kernel/ti-linux-kernel/tree/arch/arm64/boot/dts/ti/k3-j721e-sk.dts?h=ti-linux-5.10.y#n1134. For 8.x SDK that uses the 5.10 Linux kernel, it seems we define this by default. However, in 9.x SDK that uses 6.1 kernel, these node has been removed: https://git.ti.com/cgit/ti-linux-kernel/ti-linux-kernel/tree/arch/arm64/boot/dts/ti/k3-j721e-sk.dts?h=ti-linux-6.1.y. In our current case, if using the 8.1 SDK version for edgeai, then it should be enabled by default. This extra information is just a warning when moving to newer versions of the SDK that there is a need to define the device tree nodes for CAN.

Regards,

Takuma

0 Arpan Dutta over 2 years ago in reply to Takuma Fujiwara

Prodigy 60 points

Hi Takuma,

This version of image is working as expected and I am able do CAN communication between the SK and PCAN.

However, this image is a little old and doesn't have few libraries that I intend to use. The v9.1 Linux image I flashed based on recommendation seems to be for the SK board itself as mentioned on the page (PROCESSOR-SDK-LINUX-SK-TDA4VM). I would like to use this as my base image as it has all the other stuff that is required.

So now the queries are:

1. Where could I find the device tree file for this image?

2. Where do I need to place this device tree file?

3. Is there anything else I need to configure along with updating the device tree file for it to work on the preferred version of image.

Regards,
Arpan

0 Takuma Fujiwara over 2 years ago in reply to Arpan Dutta

TI__Guru 58783 points

Hi Arpan,

Arpan Dutta said:
1. Where could I find the device tree file for this image?

If you install the Linux SDK onto your PC, it should be under <SDK install directory>/board-support/linux-*/arch/arm64/boot/dts/ti. The device tree for the SK-TDA4VM board should be k3-j721e-sk.dts.

Arpan Dutta said:
2. Where do I need to place this device tree file?

Once you edit the device tree, you can build using the top-level Makefile. Instructions can be found here: https://software-dl.ti.com/jacinto7/esd/processor-sdk-linux-sk-tda4vm/09_01_00/exports/docs/linux/Overview_Top_Level_Makefile.html. The target that builds only dtb files are linux-dtbs, and to install the generated dtbs use linux-dtbs_install while specifying ROOTFS_PART in Rules.make to point to the SD card's root partition.

Arpan Dutta said:
3. Is there anything else I need to configure along with updating the device tree file for it to work on the preferred version of image.

It should just be device tree changes that are needed. The defconfig that is used to configure the kernel should have CAN built as modules. If for some reason the CAN driver is not built (for example, if you have a custom kernel configuration), then the defconfig used to build the Linux kernel can be found under <SDK install directory>/board-support/linux-*/arch/arm64/configs.

In general, there are not too many differences in format for the device tree between 8.x SDK and 9.x SDK, so theoretically, adding the CAN device tree should enable it.

Regards,

Takuma

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SK-TDA4VM: Does SK-TDA4VM board support CAN communication on linux A72? If so, how to enable it?