Dax Circuit 03

DAX-C03 is an addon board for the Nvidia Jetson TX1 Development Board that serves as a CAN master node. It has two MCP2515 CAN controller chips connected to SPI0 and SPI2 on the TX1 Display Expansion connector. Two ISO1050 isolated CAN tranceivers work as an interface between the bus and the MCP2515. The MCP2515 is controlled by the MCP251x driver that is included in the linux kernel.

Status on Jetson TX1:

• Fully working under l4t-28.2 (master)
• Fully working under l4t-24.2 (see releases)

Status on Jetson TX2:

• Fully working under l4t-28.2 (master)

Table of Contents

1. Dev Environment Setup
2. Installing the Toolchain
3. Add the DTSI
4. Compile the Kernel
5. Flash the TX

Dev Environment Setup

This section will describe the process of setting up the development environment on a fresh Ubuntu installation using Jetpack.

First download Jetpack and make the file executable

chmod +x JetPack-L4T-3.1-linux-x64.run

Next transfer the installer to its own folder.

mkdir ~/l4t_r28.2
mv JetPack-L4T-3.1-linux-x64.run ~/l4t_r28.2/

Export $DEVDIR as the new JetPack location.

export DEVDIR=~/l4t_r28.2

Now run the installer and follow the instructions. Once you get to the Package list change the action next to "Install on Target" to "no action." This will install the dev environment but skip flashing. We will be modifying the kernel to include this dtsi before flashing the image.

Installing the Toolchain

In addition to the source you'll need the toolchain for cross-compiling the kernel for ARM. Download the following two binaries.

• 64bit ARM
• 32bit ARM

Install using the following commands:

sudo mkdir /opt/linaro
sudo tar -xf gcc-linaro-5.4.1-2017.01-x86_64_aarch64-linux-gnu.tar.xz -C /opt/linaro/
sudo tar -xf gcc-linaro-5.4.1-2017.01-x86_64_arm-linux-gnueabihf.tar.xz -C /opt/linaro/

Add the DTSI

Download the kernel source code by running the source_sync script. This will take a few minutes. Specify which version using the -k tag.

cd $DEVDIR/64_TX1/Linux_for_Tegra_64_tx1/
./source_sync.sh -k tegra-l4t-r28.2

Export $SOURCEDIR as the sources directory created by source_sync.sh.

export SOURCEDIR=$DEVDIR/64_TX1/Linux_for_Tegra_64_tx1/sources

Clone the dtsi repository to the sources directory.

git clone https://github.com/DaxBot/daxc03.git $SOURCEDIR/daxc03

Jetson TX1: Create symbolic links to the new files and insert them into the kernel.

# Link dtsi files
ln -s $SOURCEDIR/daxc03/tegra210-daxc03.dtsi $SOURCEDIR/hardware/nvidia/platform/t210/jetson/kernel-dts/

# Update device tree to include new entires
echo "#include \"tegra210-daxc03.dtsi\"" >> $SOURCEDIR/hardware/nvidia/platform/t210/jetson/kernel-dts/tegra210-jetson-tx1-p2597-2180-a01-devkit.dts

Jetson TX2: Create symbolic links to the new files and insert them into the kernel.

# Link dtsi files
ln -s $SOURCEDIR/daxc03/tegra186-daxc03.dtsi $SOURCEDIR/hardware/nvidia/platform/t18x/quill/kernel-dts/

# Update device tree to include new entires
echo "#include \"tegra186-daxc03.dtsi\"" >> $SOURCEDIR/hardware/nvidia/platform/t18x/quill/kernel-dts/tegra186-quill-p3310-1000-a00-00-base.dts

Compile the Kernel

Install build tools and libraries

sudo apt update
sudo apt install -y build-essential libncurses-dev

Export the following environment variables:

export CROSS_COMPILE=/opt/linaro/gcc-linaro-5.4.1-2017.01-x86_64_aarch64-linux-gnu/bin/aarch64-linux-gnu-
export CROSS32CC=/opt/linaro/gcc-linaro-5.4.1-2017.01-x86_64_arm-linux-gnueabihf/bin/arm-linux-gnueabihf-gcc
export TEGRA_KERNEL_OUT=$SOURCEDIR/compiled

Create the default configuration:

cd $SOURCEDIR/kernel/kernel-4.4
mkdir $TEGRA_KERNEL_OUT
make ARCH=arm64 O=$TEGRA_KERNEL_OUT tegra21_defconfig

Enable driver using menuconfig

make ARCH=arm64 O=$TEGRA_KERNEL_OUT menuconfig

[*] Networking support --->
    <*> CAN bus subsystem support --->
        <*> Raw CAN Protocol (raw access with CAN-ID filtering)
        <*> Broadcast Manager CAN Protocol (with content filtering)
        <*> CAN Gateway/Router (with netlink configuration)
        CAN Device Drivers --->
            <*> Platform CAN drivers with Netlink support
            CAN SPI interfaces --->
                <*> Microchip MCP251x SPI CAN controllers

Now you can compile the kernel image and device tree blob

make ARCH=arm64 O=$TEGRA_KERNEL_OUT -j4 Image dtbs

Flash the TX

Copy the new files over to the the Jetpack kernel directory.

cp $SOURCEDIR/compiled/arch/arm64/boot/Image $SOURCEDIR/../kernel/
cp $SOURCEDIR/compiled/arch/arm64/boot/dts/*.dtb $SOURCEDIR/../kernel/dtb/

Update the kernel

scp $SOURCEDIR/compiled/arch/arm64/boot/Image [user]@[ip]:/boot/

Then restart the TX into recovery mode and flash the DTB

cd $SOURCEDIR/../
sudo ./flash.sh -r -k DTB jetson-tx1 mmcblk0p1