LVGL移植到IMX6ULL笔记

所需库文件及版本问题

所需库文件及版本如下：

1. 选择对应版本后，选择Download ZIP

2. 使用git命令克隆特定版本

   先git整个仓库

   1	git clone https://github.com/lvgl/lvgl.git

   然后切换到对应版本

   1	git checkout v8.2.0

移植文件

将上述下载到的lv_drivers lvgl 和 lv_port_linux_frame_buffer中 main.c和 Makefile文件的 放在同一目录下，比如我放在了新建的lvgl_demo目录下。
将lvgl_demo/lvgl/lv_conf_template.h复制到lvgl_demo/下并且改名位lvgl_demo/lv_conf.h
将lvgl_demo/lv_drivers/lv_drv_conf_template.h复制到lvgl_demo/下并且改名位lvgl_demo/lv_drv_conf.h
此时查看

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book@100ask:~/Desktop/lvgl_demo2$ ls
lv_conf.h  lv_drivers  lv_drv_conf.h  lvgl  main.c  Makefile

此时目录结构为：

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lvgl_demo
├── lvgl
├── lv_drivers
├── lv_conf.h
├── lv_drv_conf.h
├── main.c
└── Makefile

二级目录使用tree -L 2查看我的lvgl_demo目录结构如下：

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lvgl_demo
├── lv_conf.h
├── lv_drivers
│   ├── CMakeLists.txt
│   ├── display
│   ├── docs
│   ├── gtkdrv
│   ├── indev
│   ├── library.json
│   ├── LICENSE
│   ├── lv_drivers.mk
│   ├── lv_drv_conf_template.h
│   ├── README.md
│   ├── sdl
│   ├── wayland
│   ├── win32drv
│   ├── win_drv.c
│   ├── win_drv.h
│   └── win_drv.o
├── lv_drv_conf.h
├── lvgl
│   ├── CMakeLists.txt
│   ├── component.mk
│   ├── demos
│   ├── docs
│   ├── env_support
│   ├── examples
│   ├── idf_component.yml
│   ├── Kconfig
│   ├── library.json
│   ├── library.properties
│   ├── LICENCE.txt
│   ├── lv_conf_template.h
│   ├── lvgl.h
│   ├── lvgl.mk
│   ├── README.md
│   ├── README_zh.md
│   ├── SConscript
│   ├── scripts
│   ├── src
│   └── tests
├── main.c
└── Makefile

修改配置文件

修改lv_drv_conf.h

1. 使能驱动
   将#if 1 /*Set it to "1" to enable the content*/改为#if 1 /*Set it to "1" to enable the content*/
2. 使能frame buffer设备，将USE_FBDEV的值改为1

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   /*----------------------------------------- * Linux frame buffer device (/dev/fbx) *-----------------------------------------*/ #ifndef USE_FBDEV # define USE_FBDEV 1 #endif #if USE_FBDEV # define FBDEV_PATH "/dev/fb0" #endif

3. 使能USE_EVDEV，将/dev/input/event0改为/dev/input/event1,这里是使触摸设备生效

   1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16

   /*------------------------------------------------- * Mouse or touchpad as evdev interface (for Linux based systems) *------------------------------------------------*/ #ifndef USE_EVDEV # define USE_EVDEV 1 #endif #ifndef USE_BSD_EVDEV # define USE_BSD_EVDEV 0 #endif #if USE_EVDEV || USE_BSD_EVDEV # define EVDEV_NAME "/dev/input/event1" /*You can use the "evtest" Linux tool to get the list of devices and test them*/ # define EVDEV_SWAP_AXES 0 /*Swap the x and y axes of the touchscreen*/ # define EVDEV_CALIBRATE 0 /*Scale and offset the touchscreen coordinates by using maximum and minimum values for each axis*/

修改lv_conf.h

1. 使能，这里和上述步骤相同
   将#if 1 /*Set it to "1" to enable the content*/改为#if 1 /*Set it to "1" to enable the content*/
2. 修改显存大小
   可以使能LV_MEM_CUSTOM自己分配也可以自动分配，我选择的是自己分配显存：

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   /*1: use custom malloc/free, 0: use the built-in `lv_mem_alloc()` and `lv_mem_free()`*/ #define LV_MEM_CUSTOM 1 #if LV_MEM_CUSTOM == 0 /*Size of the memory available for `lv_mem_alloc()` in bytes (>= 2kB)*/ #define LV_MEM_SIZE (48U * 1024U) /*[bytes]*/ /*Set an address for the memory pool instead of allocating it as a normal array. Can be in external SRAM too.*/ #define LV_MEM_ADR 0 /*0: unused*/ /*Instead of an address give a memory allocator that will be called to get a memory pool for LVGL. E.g. my_malloc*/ #if LV_MEM_ADR == 0 //#define LV_MEM_POOL_INCLUDE your_alloc_library /* Uncomment if using an external allocator*/ //#define LV_MEM_POOL_ALLOC your_alloc /* Uncomment if using an external allocator*/ #endif #else /*LV_MEM_CUSTOM*/ #define LV_MEM_CUSTOM_INCLUDE <stdlib.h> /*Header for the dynamic memory function*/ #define LV_MEM_CUSTOM_ALLOC malloc #define LV_MEM_CUSTOM_FREE free #define LV_MEM_CUSTOM_REALLOC realloc #endif /*LV_MEM_CUSTOM*/

3. 刷新时间
   可修改可以不修改，记录说明这里可以按需修改

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   /*==================== HAL SETTINGS *====================*/ /*Default display refresh period. LVG will redraw changed areas with this period time*/ #define LV_DISP_DEF_REFR_PERIOD 10 /*[ms]*/ /*Input device read period in milliseconds*/ #define LV_INDEV_DEF_READ_PERIOD 10 /*[ms]*/

4. TICK的配置
   这里选择自己定义一个Tick定时器配置函数,更改后的配置如下：

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   /*Use a custom tick source that tells the elapsed time in milliseconds. *It removes the need to manually update the tick with `lv_tick_inc()`)*/ uint32_t custom_tick_get(void); #define LV_TICK_CUSTOM 1 #if LV_TICK_CUSTOM #define LV_TICK_CUSTOM_INCLUDE <stdint.h> /*Header for the system time function*/ #define LV_TICK_CUSTOM_SYS_TIME_EXPR (custom_tick_get()) /*Expression evaluating to current system time in ms*/ #endif /*LV_TICK_CUSTOM*/

5. LV_COLOR_DEPTH设置

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   /*==================== COLOR SETTINGS *====================*/ /*Color depth: 1 (1 byte per pixel), 8 (RGB332), 16 (RGB565), 32 (ARGB8888)*/ #define LV_COLOR_DEPTH 32 /*Swap the 2 bytes of RGB565 color. Useful if the display has an 8-bit interface (e.g. SPI)*/ #define LV_COLOR_16_SWAP 0

   颜色深度设置为32位，容易遗忘的设置，否则lvgl颜色显示不正常
6. 使能相应的demo模板
   这里使用的是LV_USE_DEMO_WIDGETS

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   /*=================== * DEMO USAGE ====================*/ /*Show some widget. It might be required to increase `LV_MEM_SIZE` */ #define LV_USE_DEMO_WIDGETS 1 #if LV_USE_DEMO_WIDGETS #define LV_DEMO_WIDGETS_SLIDESHOW 0 #endif

修改main.c

1. 修改显示器分辨率

   1 2	disp_drv.hor_res = 1024; disp_drv.ver_res = 600;

2. 注释鼠标输入

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   /*Set a cursor for the mouse*/ // LV_IMG_DECLARE(mouse_cursor_icon) // lv_obj_t * cursor_obj = lv_img_create(lv_scr_act()); /*Create an image object for the cursor */ // lv_img_set_src(cursor_obj, &mouse_cursor_icon); /*Set the image source*/ // lv_indev_set_cursor(mouse_indev, cursor_obj); /*Connect the image object to the driver*/

3. 注释其他不需要的地方，防止编译不通过，比如：// #include "lvgl/demos/lv_demos.h"

到这里main函数就修改完了，注意到main.c中就有custom_tick_get实现，其他可以按需修改
完整的main.c代码如下：

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#include "lvgl/lvgl.h"
// #include "lvgl/demos/lv_demos.h"
#include "lv_drivers/display/fbdev.h"
#include "lv_drivers/indev/evdev.h"
#include <unistd.h>
#include <pthread.h>
#include <time.h>
#include <sys/time.h>

// #define DISP_BUF_SIZE (128 * 1024)
#define DISP_BUF_SIZE (1024 * 600)

int main(void)
{
    /*LittlevGL init*/
    lv_init();

    /*Linux frame buffer device init*/
    fbdev_init();

    /*A small buffer for LittlevGL to draw the screen's content*/
    static lv_color_t buf[DISP_BUF_SIZE];

    /*Initialize a descriptor for the buffer*/
    static lv_disp_draw_buf_t disp_buf;
    lv_disp_draw_buf_init(&disp_buf, buf, NULL, DISP_BUF_SIZE);

    /*Initialize and register a display driver*/
    static lv_disp_drv_t disp_drv;
    lv_disp_drv_init(&disp_drv);
    disp_drv.draw_buf   = &disp_buf;
    disp_drv.flush_cb   = fbdev_flush;
    disp_drv.hor_res    = 1024;
    disp_drv.ver_res    = 600;
    lv_disp_drv_register(&disp_drv);

    evdev_init();

    // static lv_indev_drv_t indev_drv_1;
    // lv_indev_drv_init(&indev_drv_1); /*Basic initialization*/

    // indev_drv_1.type = LV_INDEV_TYPE_POINTER;

    // /*This function will be called periodically (by the library) to get the mouse position and state*/
    // indev_drv_1.read_cb = evdev_read;
    // lv_indev_t *mouse_indev = lv_indev_drv_register(&indev_drv_1);

    /* Initialize and register a display input driver */
    lv_indev_drv_t indev_drv;
    lv_indev_drv_init(&indev_drv);      /*Basic initialization*/

    indev_drv.type = LV_INDEV_TYPE_POINTER;
    indev_drv.read_cb = evdev_read;
    lv_indev_t * my_indev = lv_indev_drv_register(&indev_drv); 

    /*Set a cursor for the mouse*/
    // LV_IMG_DECLARE(mouse_cursor_icon)
    // lv_obj_t * cursor_obj = lv_img_create(lv_scr_act()); /*Create an image object for the cursor */
    // lv_img_set_src(cursor_obj, &mouse_cursor_icon);           /*Set the image source*/
    // lv_indev_set_cursor(mouse_indev, cursor_obj);             /*Connect the image  object to the driver*/


    /*Create a Demo*/
    // lv_demo_widgets();
    lv_demo_music();

    /*Handle LitlevGL tasks (tickless mode)*/
    while(1) {
        lv_timer_handler();
        usleep(5000);
    }

    return 0;
}

/*Set in lv_conf.h as `LV_TICK_CUSTOM_SYS_TIME_EXPR`*/
uint32_t custom_tick_get(void)
{
    static uint64_t start_ms = 0;
    if(start_ms == 0) {
        struct timeval tv_start;
        gettimeofday(&tv_start, NULL);
        start_ms = (tv_start.tv_sec * 1000000 + tv_start.tv_usec) / 1000;
    }

    struct timeval tv_now;
    gettimeofday(&tv_now, NULL);
    uint64_t now_ms;
    now_ms = (tv_now.tv_sec * 1000000 + tv_now.tv_usec) / 1000;

    uint32_t time_ms = now_ms - start_ms;
    return time_ms;
}

Makefile配置

1. 修改了交叉编译工具链为：CC := arm-buildroot-linux-gnueabihf-gcc.

使用echo $CROSS_COMPILE可以查看交叉编译链是什么

1. 将鼠标样式的连接源文件注释掉# CSRCS +=$(LVGL_DIR)/mouse_cursor_icon.c
   完整的Makefile如下：

   1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48

   # # Makefile # # CC ?= gcc CC := arm-buildroot-linux-gnueabihf-gcc LVGL_DIR_NAME ?= lvgl LVGL_DIR ?= ${shell pwd} CFLAGS ?= -O3 -g0 -I$(LVGL_DIR)/ -Wall -Wshadow -Wundef -Wmissing-prototypes -Wno-discarded-qualifiers -Wall -Wextra -Wno-unused-function -Wno-error=strict-prototypes -Wpointer-arith -fno-strict-aliasing -Wno-error=cpp -Wuninitialized -Wmaybe-uninitialized -Wno-unused-parameter -Wno-missing-field-initializers -Wtype-limits -Wsizeof-pointer-memaccess -Wno-format-nonliteral -Wno-cast-qual -Wunreachable-code -Wno-switch-default -Wreturn-type -Wmultichar -Wformat-security -Wno-ignored-qualifiers -Wno-error=pedantic -Wno-sign-compare -Wno-error=missing-prototypes -Wdouble-promotion -Wclobbered -Wdeprecated -Wempty-body -Wtype-limits -Wshift-negative-value -Wstack-usage=2048 -Wno-unused-value -Wno-unused-parameter -Wno-missing-field-initializers -Wuninitialized -Wmaybe-uninitialized -Wall -Wextra -Wno-unused-parameter -Wno-missing-field-initializers -Wtype-limits -Wsizeof-pointer-memaccess -Wno-format-nonliteral -Wpointer-arith -Wno-cast-qual -Wmissing-prototypes -Wunreachable-code -Wno-switch-default -Wreturn-type -Wmultichar -Wno-discarded-qualifiers -Wformat-security -Wno-ignored-qualifiers -Wno-sign-compare LDFLAGS ?= -lm BIN = demo #Collect the files to compile MAINSRC = ./main.c include $(LVGL_DIR)/lvgl/lvgl.mk include $(LVGL_DIR)/lv_drivers/lv_drivers.mk # include $(LVGL_DIR)/lv_demos/lv_demos.mk # CSRCS +=$(LVGL_DIR)/mouse_cursor_icon.c OBJEXT ?= .o AOBJS = $(ASRCS:.S=$(OBJEXT)) COBJS = $(CSRCS:.c=$(OBJEXT)) MAINOBJ = $(MAINSRC:.c=$(OBJEXT)) SRCS = $(ASRCS) $(CSRCS) $(MAINSRC) OBJS = $(AOBJS) $(COBJS) ## MAINOBJ -> OBJFILES all: default %.o: %.c @$(CC) $(CFLAGS) -c $< -o $@ @echo "CC $<" default: $(AOBJS) $(COBJS) $(MAINOBJ) $(CC) -o $(BIN) $(MAINOBJ) $(AOBJS) $(COBJS) $(LDFLAGS) mkdir -p $(LVGL_DIR)/obj $(LVGL_DIR)/bin mv *.o $(LVGL_DIR)/obj/ mv $(BIN) $(LVGL_DIR)/bin/ clean: rm -f $(BIN) $(AOBJS) $(COBJS) $(MAINOBJ) ./bin/* ./obj/*

运行和结果

1. 使用make编译后，将生成demo可执行文件。然后通过mount挂载，将编译好的demo放到开发板的/mnt/目录下

2. 开发板上切换到/mnt目录，执行.demo运行

3. 结果

   

   

   

   

注意事项

1.注意版本一致，不然容易出现各种各样稀奇古怪的问题，有可能无法编译。我甚至遇到过编译成功之后出来的可执行文件是64位的，而开发板是32位的，导致无法运行。
2.修改配置或者源码之后，如果不是预期的效果，可以试试先make clean，然后再make。

参考链接

【嵌入式Linux应用开发】1. 移植LVGL到Linux开发板