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SW Release information

Supported board Zephyr Version BSP Release date
H3ULCB 2.7 LTS [New!!] 2021/10/22
2.6 2021/06/11


This is the Wiki for the Zephyr support for Renesas R-Car Gen3 embedded Cortex-R7. Refer to the R-Car page for information about Renesas’ R-Car SoC family.

This wiki describes the current support of H3ULCB Cortex-R7 on Zephyr from multiple sources. You will also find a step by step tutorial on how to prepare your Ubuntu host then build and test Zephyr OS on an R-Car Gen3 board.

Important: It is important to understand that the Zephyr port has been designed to be executed exclusively on the Cortex-R7 that exists in some of the R-Car Gen3 boards.There is no plan to replace other software such as U-Boot or Linux that are running on the A57/53 cores by Zephyr.


This tutorial is based on the official Zephyr 2.6 guide, commands are appended here to allow you a quick copy and paste. You can also follow the installation steps (1 to 4) directly from the official guide here.

This guide only supports Ubuntu but the official one also describes steps for macOS and windows. This tutorial is based on Zephyr 2.6 version and is using the Iot.bzh’s Renesas 2.6 BSP in order to provide a much more user friendly tutorial.

You can see Zephyr 2.6’s H3ULCB supported features here.

Prepare your bootloaders

In order for Zephyr or any other RTOS running on the H3ULCB’s Cortex-R7 to work well, “ARM Trusted Firmware” needs to be patched and re-flashed. This patch enables access to GIC generated interrupts from the CR7 core on R-Car Gen3 boards.

Warning: By applying this patch and giving secure access to the CR7 core you expose yourself to unintended uses that may compromise the security of your system.

Build “ARM Trusted Firmware” (BL2)

In order to build your “ARM Trusted Firmware” with the needed patch, you have to add a Yocto layer when building your BSP with Yocto. The following instructions are tested in order to be used with the official guide for BSPs 5.9.0 and earlier.

You can apply BL2 patch by adding these lines to the script or manual steps :

  • “Clone basic Yocto layers in parallel” section :

    git clone https://github.com/renesas-rcar/meta-renesas &
    +git clone https://github.com/iotbzh/meta-rcar-zephyr &
  • “Switch to proper branches/commits” section :
    • For BSP 5.1.0 and earlier

      cd ${WORK}/meta-renesas
      git checkout -b tmp ${META_RENESAS_COMMIT}
      +cd ${WORK}/meta-rcar-zephyr
      +git checkout -b tmp cr7_5.1.0_and_earlier
    • For BSP 5.5.0 and later

      cd ${WORK}/meta-renesas
      git checkout -b tmp ${META_RENESAS_COMMIT}
      +cd ${WORK}/meta-rcar-zephyr
      +git checkout -b tmp cr7_5.5.0_and_later
  • Case 1 : You want to build a complete image Before bitbake core-image-weston :

    +bitbake-layers add-layer ../../meta/meta-rcar-zephyr/
    bitbake core-image-weston
  • Case 2 : You only want to rebuild “ARM Trusted Firmware” with the patch Replace bitbake core-image-weston by :

    -bitbake core-image-weston
    +bitbake-layers add-layer ../../meta/meta-rcar-zephyr/
    +bitbake arm-trusted-firmware

Flash bootloaders

Once you have built your new “ARM Trusted Firmware” bootloader, you may flash it by following the official flashing guide.

You may choose to only re-flash the “ARM Trusted Firmware” or re-flash all your bootloaders if you are running old versions of these.

Install dependencies

First, update your host:

sudo apt update
sudo apt upgrade

Then, install the required dependencies:

sudo apt install --no-install-recommends git cmake ninja-build gperf \
  ccache dfu-util device-tree-compiler wget \
  python3-dev python3-pip python3-setuptools python3-tk python3-wheel xz-utils file \
  make gcc gcc-multilib g++-multilib libsdl2-dev

Please also make sure that your default cmake is version 3.13.1 or higher and check here if you have minimal version for needed tools.

Get Zephyr and install Python dependencies

In order to clone Zephyr, you should first install the West tool, a swiss-army knife command line tool used by the Zephyr project for the whole process from cloning sources to flashing a board.

pip3 install --user -U west
echo 'export PATH=~/.local/bin:"$PATH"' >> ~/.bashrc
source ~/.bashrc

Clone the complete Zephyr project, use Iot.bzh’s latest Renesas BSP and update all the project:

cd ~
west init -m  https://github.com/iotbzh/zephyr.git --manifest-rev renesas-v2.6 ~/zephyrproject
cd ~/zephyrproject
west update

Export a Zephyr CMake package:

west zephyr-export

Then, install the Python dependencies:

pip3 install --user -r ~/zephyrproject/zephyr/scripts/requirements.txt

Install a toolchain

To build Zephyr OS binaries, you need a cross-toolchain. The Zephyr OS project provides all the binary files you need to build your project.

cd ~
wget https://github.com/zephyrproject-rtos/sdk-ng/releases/download/v0.12.4/zephyr-sdk-0.12.4-x86_64-linux-setup.run
chmod a+x ./zephyr-sdk-0.12.4-x86_64-linux-setup.run
./zephyr-sdk-0.12.4-x86_64-linux-setup.run -- -d ~/zephyr-sdk-0.12.4

Then, apply the provided udev rule allowing the flash of most Zephyr boards:

sudo cp ~/zephyr-sdk-0.12.4/sysroots/x86_64-pokysdk-linux/usr/share/openocd/contrib/60-openocd.rules /etc/udev/rules.d
sudo udevadm control --reload

Build demos

Now you are ready to build your first Zephyr project programs, we are going to start with a bunch of basic demos:

  • Blinky demo is making a LED blink (LED5 output LED).
  • Button demo is turning on output LED when receiving button input (SW3 input button).
cd ~/zephyrproject/zephyr

west build -p auto -b rcar_h3ulcb_cr7 samples/basic/blinky --build-dir build-h3ulcb-blinky
west build -p auto -b rcar_h3ulcb_cr7 samples/basic/button --build-dir build-h3ulcb-button

Build a custom app

As an example, we will clone the zephyr-shell demo that we prepared to demonstrate all the currently supported features for R-Car Gen3 H3ULCB on Zephyr.

You can clone your app anywhere on your host, for the clarity of this tutorial, we will store apps near to the Zephyr sources:

mkdir ~/zephyrproject/user_app
cd ~/zephyrproject/user_app
git clone https://github.com/iotbzh/zephyr-shell.git

Then, you can build it at the same location as demos previously built:

cd  ~/zephyrproject/zephyr
west build -b rcar_h3ulcb_cr7 ../user_app/zephyr-shell --build-dir build-h3ulcb-zephyr-shell

Hardware setup

Now that your binaries are ready, it’s time to prepare your hardware setup allowing you to flash the program you just built.

First, the BSP we are using is currently only supporting the Olimex ARM-USB-OCD-H JTAG probe, we then encourage you to use this probe to flash H3ULCB board.

Depending on the hardware configuration you use, you will not need the same setup:

ULCB: To connect the JTAG probe to a ULCB board, you will need a TET SICA20I2P adapter. You will then be able to connect your probe to the CN3 JTAG connector of the board. Unless your CN10 connector is welded, secondary UART is not available on this board.

ULCB+KF: When connected to a Kingfisher board, you can use JTAG and access secondary UART. You are able to access the secondary UART through KF CN4 connector (be careful, the pinout of the connector depends on your KF revision). See “Know issues” to be sure that your Kingfisher revision let you use the JTAG connector.

If you are able to access the secondary UART (depending on yor hardware setup), you can link your host to it with a USB-TTL adapter with 115200 8N1 settings.

Deploy a Zephyr binary on board

Now that your hardware setup is ready, you are able to flash any of your Zephyr binary:

Blinky demo:

cd  ~/zephyrproject/zephyr/build-h3ulcb-blinky
west flash

LED5 of H3ULCB should blink.

Button demo:

cd  ~/zephyrproject/zephyr/build-h3ulcb-button
west flash

LED5 of H3ULCB should turn on if SW3 button is pushed.

Zephyr Shell demo:

cd ~/zephyrproject/zephyr/build-h3ulcb-zehyr-shell
west flash

Zephyr shell prompt should appear on H3ULCB+KF secondary UART (KF CN4/SCIF1). You can then test subsystems support as explained in Zephyr Shell app Readme here.