CAN setup in BeagleBone AI-64

ss13ms110 · March 22, 2023, 4:50pm

Hello Devs,

I am creating this topic for people out there looking for how to setup CAN in BeagleBone AI-64. I had a long discussion with @benedict.hewson and @SunWukong (here) and they helped me to go through this. Same scheme can be followed to integrate other overlays in BB AI-64.

Image used: bbai64-debian-11.6-xfce-edgeai-arm64-2023-01-02-10gb.img.xz

Steps to setup DTS overlay for CAN in BeagleBone AI-64

Note: Apply updates from here before proceeding

Goto /opt/source/dtb-5.10-ti

$ cd /opt/source/dtb-5.10-ti/

Create new CAN0 overlay file BONE-CAN0.dts in src/arm64/overlays/

/dts-v1/;
/plugin/;

/*
 * Helper to show loaded overlays under: /proc/device-tree/chosen/overlays/
 */
&{/chosen} {
	overlays {
		BONE-CAN0.kernel = __TIMESTAMP__;
	};
};

/* Change pinmux*/

&main_mcan0 {
	pinctrl-names = "default";
	pinctrl-0 = <
		&P9_19_can_pin /* mcan0_rxd */
		&P9_20_can_pin /* mcan0_txd */
	>;
	symlink = "bone/can/1";
	status = "okay";
};

Compile and install from parent directory dtb-5.10-ti.

$ make 
$ sudo make install

After compilation edit /boot/firmware/extlinux/extlinux.conf by replacing
#fdtoverlays /overlays/<file>.dtbo
with
fdtoverlays /overlays/BONE-CAN0.dtbo

$ sudo vi /boot/firmware/extlinux/extlinux.conf

Reboot

$ sudo reboot

Test if CAN interface is loaded

$ sudo beagle-version | grep UBOOT

UBOOT: Booted Device-Tree:[k3-j721e-beagleboneai64.dts]
UBOOT: Loaded Overlay:[BONE-CAN0.kernel]

Check for CAN interface in ip link

$ ip link

can0: <NOARP,ECHO> mtu 16 qdisc noop state DOWN mode DEFAULT group default qlen 10
    link/can

It shows can0 is DOWN. To make it available run:

$ sudo ip link set can0 up type can bitrate 1000000
$ ip link 

can0: <NOARP,UP,LOWER_UP,ECHO> mtu 16 qdisc pfifo_fast state UP mode DEFAULT group default qlen 10
    link/can

Increase txqueulen

$ sudo ifconfig can0 txqueuelen 100

Representative diagram showing how to connect CAN transceivers with two BeagleBone AI-64.
Note: In order for CAN to work, you need atleast 2 nodes

Use cansend and candump to send and receive CAN signals from one BBAI-64 to other

BB AI-64 2

candump can0

BB AI-64 1

cansend can0 435#4D.99.73.21.79.89.D4.73

I hope this helps

Thank you

Best
Shubham

chkvsk · March 22, 2023, 8:01pm

fdtoverlays /overlays/BONE-CAN0.dtbo

ss13ms110 · March 23, 2023, 7:01am

Thanks @chkvsk

I have made the correction.

chkvsk · March 24, 2023, 4:06am

Sorry for the simple question. I’m using capes with CAN routed as can1 to the pins P9.24 and P9.26. Tried to complete setup with creating BONE-CAN1.dts with no success. What need to be changed in setup process to setup can1?

Thanks

benedict.hewson · March 24, 2023, 7:26am

P9.24 & P9.26 is connected to main_mcan4 so you will need in your overlay


&main_pmx0 {
   main_mcan4_pins_default:main_mcan4-pins-default {
      pinctrl-single,pins = <
      J721E_IOPAD(0x30, PIN_OUTPUT, 6)  /* AF24: PRG1_PRU0_GPO11 Y1_AF24 */
      J721E_IOPAD(0x1DC, PIN_INPUT, 7) /* Y1: SPI1_CLK Y1_AF24 */
      
      J721E_IOPAD(0x34, PIN_INPUT, 6)  /* AJ24: PRG1_PRU0_GPO12 Y5_AJ24 */
      J721E_IOPAD(0x1E0, PIN_INPUT, 7) /* Y5: SPI1_D0 Y5_AJ24 */
      
      >;
   };

};

&main_mcan4 {
	status = "okay";
	pinctrl-names = "default";
	pinctrl-0 = <&main_mcan4_pins_default >;
};

They will get enumerated as can0 and can1, however I am not 100% sure if they will always get enumerated in the same order, or that mcan4 will be can1.

You can add a udev rule to set the name for the interface. I am doing this for my 6 CAN channels as I have labelled them on the pcb, with the hardware interface.

So basically you can create a udev rule like this, which sets the name to the actual hardware peripheral.

put the file in /etc/udev/rules.d/

#11-can.rules

KERNELS=="2701000.can", ACTION=="add", NAME="CAN0"
KERNELS=="2741000.can", ACTION=="add", NAME="CAN4"
KERNELS=="2751000.can", ACTION=="add", NAME="CAN5"
KERNELS=="2761000.can", ACTION=="add", NAME="CAN6"
KERNELS=="2771000.can", ACTION=="add", NAME="CAN7"
KERNELS=="2781000.can", ACTION=="add", NAME="CAN8"

This sets my can interface names to the above, rather than can0-can5 as that is confusing for me. Put anything you like for the name.

chkvsk · March 26, 2023, 5:03pm

Thank you, It was even easier than I thought:

3: can0: <NOARP,UP,LOWER_UP,ECHO> mtu 16 qdisc pfifo_fast state UP group default qlen 10
link/can
4: can1: <NOARP,UP,LOWER_UP,ECHO> mtu 16 qdisc pfifo_fast state UP group default qlen 10
link/can

I created another BONE-CAN4.dts

/dts-v1/;
/plugin/;

/*
 * Helper to show loaded overlays under: /proc/device-tree/chosen/overlays/
 */
&{/chosen} {
    overlays {
		BONE-CAN4.kernel = __TIMESTAMP__;
    };
};

/* Change pinmux*/

&main_mcan4 {
    pinctrl-names = "default";
    pinctrl-0 = <
		&P9_24_can_pin /* mcan4_rxd */
		&P9_26_can_pin /* mcan4_txd */
    >;
    symlink = "bone/can/4";
    status = "okay";
};

It appeared as can1, exactly what I wanted.

chkvsk · March 27, 2023, 10:26pm

Hi, Any changes to the Virtual CAN (vcan)?

root@BeagleBone:/home/debian# modprobe vcan
modprobe: FATAL: Module vcan not found in directory /lib/modules/5.10.162-ti-arm64-r97

gkz · March 30, 2023, 6:33pm

Should a default CAN link appear after the CAN interface is loaded, or is an active CAN communication required?

benedict.hewson · March 30, 2023, 9:38pm

the CAN interface should show up with nothing connected, as long as they have been enabled in the device tree

gkz · April 3, 2023, 8:41pm

Following these steps, I’m unable to reliably have the CAN interface load/show up in ip link. Are there any additional steps required that is missing from this page?

Only lo and eth0 show up in ip link

benedict.hewson · April 4, 2023, 7:05am

What version of the OS are you running

cat /etc.dogtag

If you haven’t updated the board, I suggest doing that first.

When the CAN fails to show up if you do

ls /proc/device-tree/chosen/overlays/

does the CAN overlay show up ? (might be slightly wrong on the path, going from memory)

Have you got a serial console cable ? It would certainly help to see what u-boot is doing.

gzw19980130 · September 15, 2023, 5:57am

Hi. I’m sorry, but I have some questions.
Under what file path should I create the main mcan4 overlay
I followed the above, but still can’t use CAN4, I’m too small

benedict.hewson · September 15, 2023, 6:13am

Ok assuming a standard install, on your BBAI64 you need to place the overlay source file into something like

/opt/source/dtb-5.10-ti/src/arm64/overlays

The dtb-5.10-ti part might be slightly different on your board depending on what version you are running.

Then

cd /opt/source/dtb-5.10-ti
make && make install

That should compile and copy the dts files. You either need to be root of change the above make install to sudo make install

gzw19980130 · September 15, 2023, 12:53pm

benedict.hewson:

&main_pmx0 {
   main_mcan4_pins_default:main_mcan4-pins-default {
      pinctrl-single,pins = <
      J721E_IOPAD(0x30, PIN_OUTPUT, 6)  /* AF24: PRG1_PRU0_GPO11 Y1_AF24 */
      J721E_IOPAD(0x1DC, PIN_INPUT, 7) /* Y1: SPI1_CLK Y1_AF24 */
      
      J721E_IOPAD(0x34, PIN_INPUT, 6)  /* AJ24: PRG1_PRU0_GPO12 Y5_AJ24 */
      J721E_IOPAD(0x1E0, PIN_INPUT, 7) /* Y5: SPI1_D0 Y5_AJ24 */
      
      >;
   };

};

&main_mcan4 {
	status = "okay";
	pinctrl-names = "default";
	pinctrl-0 = <&main_mcan4_pins_default >;
};

Do I need to add this code to my new BONE-CAN4.dts text

benedict.hewson · September 15, 2023, 12:54pm

yes

kkkkk · April 22, 2024, 6:32pm

Hello,

I am trying to integrate CAN on BeagleBone AI-64, I am encountering difficulties in loading CAN1, while I have successfully loaded CAN0 following the provided steps.

Thank you,

benedict.hewson · April 23, 2024, 3:01pm

Have you got a suitable overlay loaded ? Which pins are you using ?

kkkkk · April 23, 2024, 8:08pm

Hi,
I’m using pin P9_25 and P9_26 this is the overlay code for can1:

/dts-v1/;
/plugin/;
/*

Helper to show loaded overlays under: /proc/device-tree/chosen/overlays/
*/

&{/chosen} {
overlays {
BONE-CAN4.kernel = TIMESTAMP;
};
};
/* Change pinmux*/

&main_mcan4 {
pinctrl-names = “default”;
pinctrl-0 = <
&P9_24_can_pin /* mcan4_rxd /
&P9_26_can_pin / mcan4_txd */
>;
symlink = “bone/can/4”;
status = “okay”;
};

Thanks

benedict.hewson · April 24, 2024, 6:18am

Are you sure about that ? mcan4 is not available on P9_25, but is P9_24 as you are setting in the overlay.

I haven’t checked, but do those macros also set the other shared pin ?
This does work for me.

	main_mcan4_pins_default:main_mcan4-pins-default {
		pinctrl-single,pins = <
		J721E_IOPAD(0x30, PIN_OUTPUT, 6)  /* AF24: PRG1_PRU0_GPO11 Y1_AF24 */
		J721E_IOPAD(0x1DC, PIN_INPUT, 7) /* Y1: SPI1_CLK Y1_AF24 */

		J721E_IOPAD(0x34, PIN_INPUT, 6)  /* AJ24: PRG1_PRU0_GPO12 Y5_AJ24 */
		J721E_IOPAD(0x1E0, PIN_INPUT, 7) /* Y5: SPI1_D0 Y5_AJ24 */

		>;
	};

kkkkk · April 24, 2024, 11:59am

Sorry for confusion, I’m using pin P9_24 and P9_26 for mcan4
Do I need to add these macros in the same file (BONE-CAN4.dts)?

Thanks