NemaGFX Acceleration (AKA NeoChrom)
Some of the more powerful STM32 MCUs such as the STM32U5 feature a 2.5D GPU which can natively draw most LVGL primitives.
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
"src/draw/nema_gfx/lv_draw_nema_gfx_hal.c" implements the HAL functionality required by Nema to allocate memory and lock resources (in this implementation, no locking is done). It may conflict with existing definitions if you have an existing Nema HAL implementation. You may simply be able to remove yours.
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.