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Milk-V Duo Examples

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This project provides some examples of developing applications using C/C++ in a Linux environment, which can be run on the Milk-V Duo device.


Build environment on Ubuntu20.04

You can also use Ubuntu installed in a virtual machine, Ubuntu installed via WSL on Windows, or Ubuntu-based systems using Docker.

  • Install the tools that compile dependencies.

    sudo apt-get install wget git make

  • Get example source code

    git clone https://github.com/milkv-duo/duo-examples.git

  • Prepare compilation environment

    cd duo-examples
source envsetup.sh

    The first time you source it, the required SDK package will be automatically downloaded, which is approximately 180MB in size. Once downloaded, it will be automatically extracted to the duo-examples directory with the name duo-sdk. When source it next time, if the directory already exists, it will not be downloaded again.

  • Compile testing

    Take hello-world as an example, enter the hello-world directory and execute make

    cd hello-world
make

    After the compilation is successful, send the generated helloworld executable program to the Duo device through the network port or the RNDIS network. For example, the RNDIS method supported by the default firmware, Duo’s IP is 192.168.42.1, the user name is root, and the password is milkv

    scp helloworld root@192.168.42.1:/root/

    After sending successfully, run ./helloworld in the terminal logged in via ssh or serial port, and it will print Hello, World!

    [root@milkv]~# ./helloworld
Hello, World!

    At this point, our compilation and development environment is ready for use.

How to create your own project

You can simply copy existing examples and make necessary modifications. For instance, if you need to manipulate a GPIO, you can refer to the blink example. LED blinking is achieved by controlling the GPIO's voltage level. The current SDK utilizes the WiringX library for GPIO operations, which has been adapted specifically for Duo. You can find the platform initialization and GPIO control methods in the blink.c code for reference.

  • Create your own project directory called my-project.
  • Copy the blink.c and Makefile files from the blink example to the my-project directory.
  • Rename blink.c to your desired name, such as gpio_test.c.
  • Modify the Makefile by changing TARGET=blink to TARGET=gpio_test.
  • Modify gpio_test.c to implement your own code logic.
  • Execute the make command to compile.
  • Send the generated gpio_test executable program to Duo for execution.

Note:

  • Creating a new project directory is not mandatory to be placed within the duo-examples directory. You can choose any location based on your preference. Before executing the make compilation command, it is sufficient to load the compilation environment from the duo-examples directory (source /PATH/TO/duo-examples/envsetup.sh).
  • Within the terminal where the compilation environment (envsetup.sh) is loaded, avoid compiling Makefile projects for other platforms such as ARM or X86. If you need to compile projects for other platforms, open a new terminal.

Explanation of each example

hello-world

A simple example that doesn't interact with Duo peripherals, only prints the output "Hello, World!" to verify the development environment.

blink

This example demonstrates how to control an LED connected to a GPIO pin. It uses the WiringX library to toggle the GPIO pin's voltage level, resulting in the LED blinking.

The blink.c code includes platform initialization and GPIO manipulation methods from the WiringX library.

To test the blink example, which involves LED blinking, you need to disable the script responsible for the automatic LED blinking on the default firmware of Duo. In the Duo terminal, execute the following command:

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

This command renames the LED blinking script. After restarting Duo, the LED will no longer blink.

Once you have finished testing the blink program implemented in C, if you want to restore the LED blinking script, you can rename it back using the following command and then restart Duo:

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

I2C

App Description
bmp280_i2c By connecting the temperature and pressure sensor BMP280 through the I2C interface, you can read the current temperature and pressure values.

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