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Zephyr

What is Zephyr?（Zephyr是什么？）

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Zephyr is an open source real-time operating system (RTOS) that is easy to deploy, secure, connect and manage. It has a growing set of software libraries that can be used across various applications and industry sectors such as Industrial IoT, wearables, machine learning and more. Zephyr is built with an emphasis on broad chipset support, security, dependability, longterm support releases and a growing open source ecosystem.


Zephyr 是一个 `开源

<https://github.com/zephyrproject-rtos/zephyr>`__ 的实时操作系统（RTOS），它易于部署、安全、可连接和管理。 它拥有一套不断增长的软件库，可用于各种应用和行业领域，如工业物联网、可穿戴设备、机器学习等。 Zephyr的构建重点在于广泛的芯片组支持、安全性、可靠性、长期支持发布和不断增长的开源生态系统。

Highlights of Zephyr（Zephyr的亮点）

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  • Small - Runs on microcontrollers as small as 8 kB Flash and 5 kB of RAM.

  • Scalable - Usable for complex multicore systems.

  • Customizable - Out-of-the-box support for 500+ boards and high portability.

  • Secure - Built with safety and security in mind, offers Long-term support.

  • Ecosystem - Zephyr not only provides the RTOS kernel but also developer tooling, device drivers, connectivity, logging, tracing, power management and much more.

  • Decoupling - Leverages devicetree to describe and configure the target system.

  • Compliant - Apps are runnable as native Linux applications, which simplifies debugging and profiling.


  • 小巧 - 可运行在仅8 kB Flash和5 kB RAM的微控制器上。

  • 可扩展 - 可用于复杂的多核系统。

  • 可定制 - 提供500多个板卡的开箱即用支持和高度可移植性。

  • 安全 - 在构建时考虑到安全性和可靠性，提供长期支持。

  • 生态系统 - Zephyr不仅提供RTOS内核，还提供开发工具、设备驱动程序、连接性、日志记录、跟踪、电源管理等。

  • 解耦 - 利用设备树描述和配置目标系统。

  • 兼容 - 应用程序可作为本地Linux应用程序运行，从而简化调试和性能分析。

How to run LVGL on Zephyr?（如何在Zephyr上运行LVGL？）

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To setup your development environment refer to the getting started guide.

After you completed the setup above you can check out all of the provided samples for various boards. You can check the list of available boards using:


要设置您的开发环境，请参阅 入门指南。

完成上述设置后，您可以查看各种板卡的 提供的示例。 您可以使用以下命令查看可用板卡的列表：

$ west boards
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After you chose a board you can build one of the LVGL demos for it. Here we are using the native_posix board, which allows for running the application on your posix compliant host system:


选择板卡后，您可以为其构建LVGL演示之一。在此，我们使用的是 native_posix 板卡， 它允许在符合POSIX标准的主机系统上运行应用程序：

$ west build -b native_posix samples/modules/lvgl/demos
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To run the application on your host:


要在主机上运行应用程序，您需要执行以下步骤：

$ west build -t run
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In case you chose any of the other supported boards you can flash to the device with:


如果您选择了其他受支持的板卡之一，您可以使用以下命令将应用程序闪存到设备中：

$ west flash
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If you want to build any of the other demo applications check out the samples README.


如果您想构建其他任何演示应用程序， 请查阅示例的 README 文件。

Leveraging Zephyr Features（利用Zephyr特性）

Shell

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Zephyr includes a powerful shell implementation that can be enabled with the Kconfig symbols:code:CONFIG_SHELL and CONFIG_LV_Z_SHELL (the demos from above have it enabled by default).

The shell offers enabling/disabling of LVGL monkeys:


Zephyr包含了一个强大的shell实现，可以通过Kconfig符号 CONFIG_SHELL 和 CONFIG_LV_Z_SHELL （上面的演示默认启用了它们）来启用。

shell提供了启用/禁用LVGL猴子的功能：

# Create a new monkey with the given indev type
uart$ lvgl monkey create [pointer|keypad|button|encoder]

# Enable/Disable a monkey
uart$ lvgl monkey set <index> <inactive/active>
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This is useful for checking your application for memory leaks and other bugs. Speaking of memory leaks, you can also acquire stats of the memory used by LVGL


这对于检查应用程序是否存在内存泄漏和其他错误非常有用。说到内存泄漏，您还可以获取LVGL使用的内存统计信息。

uart$ lvgl stats memory
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For more details refer to the shell documentation.


更多详细信息， 请参阅shell文档 。

Devicetree（设备树）

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Zephyr uses the devicetree description language to create and manage LVGL input devices.

The pseudo device binding descriptions can be found at:

Essentially those buffer the input_event generated by the device pointed to by the input phandle or if left empty the binding captures all events regardless of the source. You do not have to instantiate or manage the devices yourself, they are created at application start up before main() is executed.

Most boards or shields that have a display or display connector have the pointer input device already declared:


Zephyr使用devicetree描述语言来创建和管理LVGL输入设备。

伪设备绑定描述可以在以下位置找到：

这些设备本质上缓冲了由 input phandle 指向的设备生成的 input_event， 如果留空，则绑定会捕获所有事件，而不管其来源如何。 您不必自己实例化或管理设备，它们在应用程序启动并在执行 main() 之前创建。

大多数板卡或带有显示屏或显示连接器的挡板都已经声明了指针输入设备：

lvgl_pointer {
    compatible = "zephyr,lvgl-pointer-input";
    input = <&ft5336_touch>;
};
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You can access the underlying lvgl lv_indev_t for configuration. Example with the encoder device to assign a lv_group_t:


您可以通过访问底层的lvgl lv_indev_t 来进行配置。以下是一个示例，使用编码器设备分配一个 lv_group_t：

const struct device *lvgl_encoder = DEVICE_DT_GET(DT_COMPAT_GET_ANY_STATUS_OKAY(zephyr_lvgl_encoder_input));

lv_obj_t *arc;
lv_group_t *arc_group;

arc = lv_arc_create(lv_screen_active());
lv_obj_align(arc, LV_ALIGN_CENTER, 0, 0);
lv_obj_set_size(arc, 150, 150);

arc_group = lv_group_create();
lv_group_add_obj(arc_group, arc);
lv_indev_set_group(lvgl_input_get_indev(lvgl_encoder), arc_group);

Kconfig（配置）

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Aside from enabling the shell you can also use Kconfig to finetune the footprint of your application.


除了启用shell外，您还可以使用Kconfig来微调应用程序的占用空间。

# Size of the memory region from which lvgl memory is allocated
CONFIG_LV_Z_MEM_POOL_SIZE=8192

# Do not include every widget/theme by default, enable them as needed.
CONFIG_LV_CONF_MINIMAL=y
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Overlays can be used to enable/disable features for specific boards or build targets. For more information refer to the application development guide。


可以通过Overlays启用或禁用特定板卡或构建目标的特性。 更多信息请参阅 应用程序开发指南。

Performance Tuning in LVGL（LVGL 性能调优）

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To optimize LVGL's performance, several kconfig options can be configured:

  • CONFIG_LV_Z_VDB_SIZE: Sets the rendering buffer size as a percentage of the display area, adjustable from 1% to 100%. Larger buffers can enhance performance, especially when used with CONFIG_LV_Z_FULL_REFRESH.

  • CONFIG_LV_Z_DOUBLE_VDB: Enables the use of two rendering buffers, allowing for parallel rendering and data flushing, thus improving responsiveness and reducing latency.

  • CONFIG_LV_Z_VDB_ALIGN: Ensures that the rendering buffer is properly aligned, which is critical for efficient memory access based on the color depth.

  • CONFIG_LV_Z_VBD_CUSTOM_SECTION: Allows rendering buffers to be placed in a custom memory section (e.g., .lvgl_buf), useful for leveraging specific memory types like tightly coupled or external memory to enhance performance.


为了优化 LVGL 的性能，可以配置多个 kconfig 选项：

  • CONFIG_LV_Z_VDB_SIZE：设置渲染缓冲区大小为显示区域的百分比，可调节范围从 1% 到 100%。较大的缓冲区可以提高性能，特别是与 CONFIG_LV_Z_FULL_REFRESH 一起使用时。

  • CONFIG_LV_Z_DOUBLE_VDB：启用使用两个渲染缓冲区，允许并行渲染和数据刷新，从而提高响应性和减少延迟。

  • CONFIG_LV_Z_VDB_ALIGN：确保渲染缓冲区正确对齐，这对于基于颜色深度的有效内存访问至关重要。

  • CONFIG_LV_Z_VBD_CUSTOM_SECTION：允许将渲染缓冲区放置在自定义内存段（例如 .lvgl_buf），有助于利用特定类型的内存（如紧密耦合或外部内存）来提高性能。

Zephyr ≤ 3.7.0 Specific Options（Zephyr ≤ 3.7.0 特定选项）

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For Zephyr versions 3.7.0 and below, additional options are available to manage LVGL's frame flushing:

  • CONFIG_LV_Z_FLUSH_THREAD: Enables flushing LVGL frames in a separate thread, allowing the main thread to continue rendering the next frame simultaneously. This option can be disabled if the performance gain is not needed.

    • CONFIG_LV_Z_FLUSH_THREAD_STACK_SIZE: Specifies the stack size for the flush thread, with a default of 1024 bytes.

    • CONFIG_LV_Z_FLUSH_THREAD_PRIO: Sets the priority of the flush thread, with a default priority of 0, indicating cooperative priority.

For newer versions of Zephyr, the OSAL (Operating System Abstraction Layer) can be utilized, which takes care of the flushing.


对于 Zephyr 3.7.0 及以下版本，还有额外的选项可用于管理 LVGL 的帧刷新：

  • CONFIG_LV_Z_FLUSH_THREAD: 在单独的线程中刷新 LVGL 帧，允许主线程同时继续渲染下一帧。如果不需要性能增益，可以禁用此选项。

    • CONFIG_LV_Z_FLUSH_THREAD_STACK_SIZE: 指定刷新线程的堆栈大小，默认为 1024 字节。

    • CONFIG_LV_Z_FLUSH_THREAD_PRIO: 设置刷新线程的优先级，默认优先级为 0，表示合作优先级。

对于较新版的 Zephyr，可以使用 OSAL（操作系统抽象层），它负责处理刷新。

Where can I find more information?（在哪里可以找到更多信息？ ）

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