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Project Introduction

Milk-V Duo is an ultra-compact embedded development platform based on the CV1800B chip. It can run Linux and RTOS, providing a reliable, low-cost, and high-performance platform for professionals, industrial ODMs, AIoT enthusiasts, DIY hobbyists, and creators.

Hardware

• CPU: CVITEK CV1800B (C906@1Ghz + C906@700MHz)
• Dual RV64 Core up to 1GHz
• 64MB RAM
• Provides 10/100Mbps Ethernet via optional add-on board

SDK Directory Structure

├── build               // compilation scripts and board configs
├── build_milkv.sh      // one-click compilation script
├── buildroot-2021.05   // buildroot source code
├── freertos            // freertos system
├── fsbl                // fsbl firmware in prebuilt form
├── install             // temporary images stored here
├── isp_tuning          // camera effect parameters
├── linux_5.10          // linux kernel
├── middleware          // self-developed multimedia framework
├── milkv               // configuration files for milkv
├── opensbi             // opensbi library
├── out                 // final image for SD card
├── ramdisk             // prebuilt ramdisk
└── u-boot-2021.10      // u-boot source code

Quick Start

Prepare the Compilation Environment

• Using a local Ubuntu system, Ubuntu 20.04 LTS is recommended.
  (You can also use Ubuntu installed in a virtual machine, Ubuntu installed through WSL on Windows, or Ubuntu-based systems using Docker)
• Install a serial port tool: mobaXterm or Xshell or others.

Tools to be installed on Ubuntu 20.04 LTS

Install the tools that compile dependencies:

sudo apt install -y pkg-config build-essential ninja-build automake autoconf libtool wget curl git gcc libssl-dev bc slib squashfs-tools android-sdk-libsparse-utils jq python3-distutils scons parallel tree python3-dev python3-pip device-tree-compiler ssh cpio fakeroot libncurses5 flex bison libncurses5-dev genext2fs rsync unzip dosfstools mtools tclsh ssh-client android-sdk-ext4-utils

Note：cmake minimum version requirement is 3.16.5

Check the version of cmake in the system

cmake --version

The version of cmake installed using apt in the current Ubuntu 20.04 is

cmake version 3.16.3

The minimum requirement of this SDK is not met. Manual installation of the latest version 3.27.6 is needed.

wget https://github.com/Kitware/CMake/releases/download/v3.27.6/cmake-3.27.6-linux-x86_64.sh
chmod +x cmake-3.27.6-linux-x86_64.sh
sudo sh cmake-3.27.6-linux-x86_64.sh --skip-license --prefix=/usr/local/

When manually installed, cmake is located in /usr/local/bin. To check its version, use the command cmake --version, which should display

cmake version 3.27.6

Tools to be installed on Ubuntu 22.04 LTS

Install the tools that compile dependencies:

sudo apt install -y pkg-config build-essential ninja-build automake autoconf libtool wget curl git gcc libssl-dev bc slib squashfs-tools android-sdk-libsparse-utils jq python3-distutils scons parallel tree python3-dev python3-pip device-tree-compiler ssh cpio fakeroot libncurses5 flex bison libncurses5-dev genext2fs rsync unzip dosfstools mtools tcl openssh-client cmake

Additionally, the mkimage command in the SDK relies on libssl1.1. Sometimes the system won't contain that because it has been deprecated, use dpkg -s libssl1.1 to check if you have installed it.

If not, the following two methods are both applicable:

1. Installation with additional repositories

   echo "deb http://security.ubuntu.com/ubuntu focal-security main" | sudo tee /etc/apt/sources.list.d/focal-security.list
   sudo apt update
   sudo apt install libssl1.1

2. Manual download and installation of the deb package

   wget http://security.ubuntu.com/ubuntu/pool/main/o/openssl/libssl1.1_1.1.1f-1ubuntu2.19_amd64.deb
   sudo dpkg -i libssl1.1_1.1.1f-1ubuntu2.19_amd64.deb

Compile the Image

Get SDK Source Code

git clone https://github.com/milkv-duo/duo-buildroot-sdk.git --depth=1

One-click Compilation

• Execute the one-click compilation script build_milkv.sh

cd duo-buildroot-sdk/
./build_milkv.sh

• After a successful compilation, you can find the generated SD card burning image milkv-duo-*-*.img in the out directory

Note: The first compilation will automatically download the required toolchain, which is approximately 840MB in size. Once downloaded, it will be automatically extracted to the host-tools directory in the SDK directory. For subsequent compilations, if the host-tools directory is detected, the download will not be performed again

Step-by-step Compilation

If you wish to perform step-by-step compilation, you can enter the following commands sequentially

export MILKV_BOARD=milkv-duo
source milkv/boardconfig-milkv-duo.sh

source build/milkvsetup.sh
defconfig cv1800b_milkv_duo_sd
clean_all
build_all
pack_sd_image

Location of the generated image: install/soc_cv1800b_milkv_duo_sd/milkv-duo.img

SD card burning

Note: Writing the image to the microSD card will erase the existing data on the card. Remember to back up important data before burning!!!

• To write the generated image to a microSD card on Windows, you can use tools like balenaEtcher, Rufus, or Win32 Disk Imager
• To write the generated image to a microSD card on Linux, use the dd command. Please make sure to carefully confirm that the of device /dev/sdX corresponds to the microSD card you want to burn

  sudo dd if=milkv-duo-*-*.img of=/dev/sdX
  

Power ON

• Insert the microSD card into the microSD card slot of the Milk-V Duo
• Connect the serial cable (optional)
• Power on, the Duo will boot up and enter the system normally
• If a serial cable is connected, you can view the boot logs in the serial console. After entering the system, you can use the serial console to log in to the terminal and execute relevant Linux commands

The method to log in to the Duo terminal

• Using a serial cable
• Using a USB network (RNDIS)
• Using the Ethernet interface (requires the IO-Board)

The username and password for logging into the Duo terminal are as follows:

root
milkv

To disable LED blinking

If you want to disable the LED blinking feature on the Duo, you can execute the following command in the Duo terminal:

mv /mnt/system/blink.sh /mnt/system/blink.sh_backup && sync

This means renaming the LED blinking script, and after restarting the Duo, the LED will no longer blink.

If you want to restore LED blinking, rename it back to its original name and restart the device.

mv /mnt/system/blink.sh_backup /mnt/system/blink.sh && sync

Using the IO-Board baseboard

Note that when using the IO-Board, the USB network (RNDIS) is not available, Please use the Ethernet interface on the IO-Board

If you need to assign a fixed MAC address to the Ethernet port of the IO-Board, please execute the following command(Replace the MAC address in the command with the MAC address you want to set, and please note that MAC addresses of different devices within the same network segment must not be duplicated)

echo "pre-up ifconfig eth0 hw ether 78:01:B3:FC:E8:55" >> /etc/network/interfaces

then reboot the board

Enable the 4 USB ports on the IO-Board:

rm /mnt/system/usb.sh
ln -s /mnt/system/usb-host.sh /mnt/system/usb.sh
sync

then reboot the board

For example, if a USB flash drive is connected to the USB port on the IO-Board, you can use the command ls /dev/sd* to check if the device is detected

To mount the USB drive and view its contents in the system (taking /dev/sda1 as an example):

mkdir /mnt/udisk
mount /dev/sda1 /mnt/udisk

Verify if the contents in the /mnt/udisk directory match the expectations

ls /mnt/udisk

The command to unmount a USB flash drive

umount /mnt/udisk

To restore the functionality of the USB network (RNDIS) when not using the IO-Board, you can follow these steps

rm /mnt/system/usb.sh
ln -s /mnt/system/usb-rndis.sh /mnt/system/usb.sh
sync

then reboot the board

FAQs

1. Why is only a single core being displayed?

   The CV1800B chip adopts a dual-core design. Currently, the Linux system runs on one of the cores, while the other core is used for running a real-time system. The SDK for this core has not been released yet and will be updated in the future

2. Why does it only show 28M when viewing the RAM?

   Because a portion of the RAM is allocated to ION, which is the memory used when running algorithms with the camera. If you're not using the camera, you can modify the value of this ION_SIZE to 0 and then recompile to generate the image

Links to some documentation from the chip manufacturer

• CV181x/CV180x MMF SDK Development Documents (Chinese): MultiMedia Framework Software Development Document
• CV Series Chip TPU SDK Development Documentation Compilation (Chinese): CV series chip TPU SDK development data summary

About Milk-V

• Official Website

FORUM

• MilkV Community