NemaGFX Acceleration

NemaGFX is a high-level graphics API supported by many embedded 2.5D GPUs. LVGL can use it to natively render LVGL graphics.

Get Started with the Riverdi STM32U5 5-inch Display

lv_port_riverdi_stm32u5 is a ready-to-use port for the Riverdi STM32 5.0" Embedded Display (STM32U599NJH6Q or STM32U5A9NJH6Q) which has Nema enabled. Follow the instructions in the readme to get started.

Usage and Configuration

Enable the renderer by setting LV_USE_NEMA_GFX to 1 in lv_conf.h. If using LV_USE_NEMA_VG, set LV_NEMA_GFX_MAX_RESX and LV_NEMA_GFX_MAX_RESY to the size of the display you will be using so that enough static memory will be reserved for VG. Without VG, more task types will be performed by the software renderer.

"libs/nema_gfx" contains pre-compiled binaries for the Nema GPU drivers. In lv_port_riverdi_stm32u5 the project is already configured to link the binaries when building. With a different STM32CubeIDE project, you can configure the libraries to be linked by right-clicking the project in the "Project Explorer" sidebar, clicking "Properties", navigating to "C/C++ Build", "Settings", "MCU G++ Linker", and then "Libraries". Add an entry under "Libraries (-l)" that is "nemagfx-float-abi-hard". Add an entry under "Library search path (-L)" which is a path to "libs/nema_gfx/lib/core/cortex_m33/gcc" e.g. "${workspace_loc:/${ProjName}/Middlewares/LVGL/lvgl/libs/nema_gfx/lib/core/cortex_m33/gcc}". You will also want to add the "libs/nema_gfx/include" directory to your include search paths. Under "MCU GCC Compiler", "Include paths", add an entry to "Include paths (-I)" which is a path to "libs/nema_gfx/include" e.g. "${workspace_loc:/${ProjName}/Middlewares/LVGL/lvgl/libs/nema_gfx/include}". Click "Apply and Close".

32 and 16 bit LV_COLOR_DEPTH is supported.

At the time of writing, LV_USE_OS support is experimental and not yet working in lv_port_riverdi_stm32u5

NemaGFX requires a simple HAL implementation to allocate memory and optionally lock resources. You may use a custom HAL implementation for your platform or use one of the provided implementations by setting LV_USE_NEMA_HAL to a value other than LV_NEMA_HAL_CUSTOM.

TSC Images

TSC (ThinkSillicon Compression) images can be drawn by this renderer. The TSC 4/6/6A/12/12A color formats are part of lv_color_format_t. All other renderers will ignore images with these color formats. Define an image descriptor variable with the corresponding TSC color format and the GPU will be able to draw it directly. Stride does not need to be specified because it will be computed by the renderer.

const lv_image_dsc_t img_demo_widgets_avatar_tsc6a = {
    .header.cf = LV_COLOR_FORMAT_NEMA_TSC6A,
    .header.w = 144,
    .header.h = 144,
    .data = img_demo_widgets_avatar_tsc6a_map,
    .data_size = sizeof(img_demo_widgets_avatar_tsc6a_map),
};

DMA2D

The Nema renderer uses DMA2D to flush in parallel with rendering in lv_port_riverdi_stm32u5.

If your STM does not have the Nema GPU, it may still support DMA2D. DMA2D is a simple peripheral which can draw fills and images independently of the CPU. See the LVGL DMA2D support.

API

lv_draw_nema_gfx.h

lv_draw_nema_gfx_utils.h .. Autogenerated

lv_nema_gfx_path.h