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Linux Framebuffer Driver

Overview

The Linux framebuffer (fbdev) is a linux subsystem used to display graphics. It is a hardware-independent API that gives user space software access to the framebuffer (the part of a computer's video memory containing a current video frame) using only the Linux kernel's own basic facilities and its device file system interface, avoiding the need for libraries that implement video drivers in user space.

Prerequisites

Your system has a framebuffer device configured (usually under /dev/fb0).

Configuring the driver

Enable the framebuffer driver support in lv_conf.h, by cmake compiler define or by KConfig. Additionally you may configure the rendering mode.

#define LV_USE_LINUX_FBDEV           1
#define LV_LINUX_FBDEV_RENDER_MODE   LV_DISPLAY_RENDER_MODE_PARTIAL

Usage

To set up a framebuffer-based display, first create a display with lv_linux_fbdev_create. Afterwards set the framebuffer device node on the display (usually this is /dev/fb0).

lv_display_t *disp = lv_linux_fbdev_create();
lv_linux_fbdev_set_file(disp, "/dev/fb0");

If your screen stays black or only draws partially, you can try enabling direct rendering via LV_DISPLAY_RENDER_MODE_DIRECT. Additionally, you can activate a force refresh mode with lv_linux_fbdev_set_force_refresh(true). This usually has a performance impact though and shouldn't be enabled unless really needed.