ESP-IDF and SPIFFS

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1

My device is a WT32-SC01 Plus and I wanted to use LVGL with ESP-IDF (no Arduino Core) to show images, which I downloaded from my server. So the images aren’t as C files. The files should be stored in flash within the spiffs partition.

My code is as following

static auto *image = lv_image_create(lv_scr_act());
lv_image_set_src(image, "S:image.png");
lv_obj_align(image, LV_ALIGN_TOP_LEFT, 0, 0);

I used the lv_conf.h for the setup

#define LV_USE_FS_POSIX 1
 #if LV_USE_FS_POSIX
    #define LV_FS_POSIX_LETTER 'S' 
    #define LV_FS_POSIX_PATH ""
    #define LV_FS_POSIX_CACHE_SIZE 0
#endif

To test my setup, I created an image and bundled it within the binary

spiffs_create_partition_image(storage ../storage FLASH_IN_PROJECT)

But I always see in the log an error message

W (1695) LVGL: [Warn] lv_image_set_src: failed to get image info: S:image.png lv_image.c:189

Now I’m not sure, if my file is in the storage.bin or if lvgl just has an failure while reading.

2

SPIFFS doesn’t use POSIX file functions to access the files. You would need to write your own custom driver.

If you use fatfs which is also built into the ESP-IDF then you can use POSIX functions to access the files.

https://docs.espressif.com/projects/esp-idf/en/stable/esp32/api-reference/storage/fatfs.html

using SPIFFS is a really bad idea and you can read about why it is not a good idea in the link below.

https://docs.espressif.com/projects/esp-idf/en/stable/esp32/api-reference/storage/spiffs.html#notes

3

Where can I find the documentation for a custom driver? I want to go this route.

I know spiffs wouldn‘t be good, but it was my first idea.

4

Here is the API documentation…

https://docs.lvgl.io/9.2/API/misc/lv_fs.html#

and here is a little bit more information…

https://docs.lvgl.io/9.2/libs/fs.html

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5

https://docs.lvgl.io/9.2/integration/chip/espressif.html#using-the-file-system-under-esp-idf

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