samples: video: capture_to_lvgl: disable LVGL color swap for mini_stm32h743

[CharlesDias]

Disable CONFIG_LV_COLOR_16_SWAP for the mini_stm32h743 board to ensure proper color display in the capture_to_lvgl video sample. Issue #93067

I don't know when this problem has begun, but the color format on capture_to_lvgl is broken for mini_stm32h743 and weact_ov2640_cam_module.

Command:
west build -p -b mini_stm32h743 --shield weact_ov2640_cam_module samples/drivers/video/capture_to_lvgl/ -- -DCONFIG_BOOT_DELAY=2000

Output image:

After disable the CONFIG_LV_COLOR_16_SWAP the color format is correct. However, the background on CPU and FPS monitor are is not good.

[sonarqubecloud]

Quality Gate passed

Issues
0 New issues
0 Accepted issues

Measures
0 Security Hotspots
0.0% Coverage on New Code
0.0% Duplication on New Code

See analysis details on SonarQube Cloud

[JarmouniA]

See #92343 and #92483

[avolmat-st]

I didn't notice issue on my side when trying with my boards (STM32 but not this board and not this sensor). Would it be also possible to confirm that the frame given by the sensor itself ? Is it possible for you to dump it into memory, say via GDB or something like that in order to inspect the data from an external machine ? UVC sample might be a candidate as well. I mean trying to figure out if that is an LTDC issue or a sensor / dcmi issue.

[CharlesDias]

Hi @avolmat-st,

This board does not use the LTDC. The display is the model ST7735R.

This problem doesn't exist with stm32h7b3i_dk and st_b_cams_omv_mb1683.

[josuah]

I think this does not really solve the problem fully:

Before: gray overlay looks correct

After: gray overlay looks rainbowy:

This mean we might need a bit more investigation to align definition a bit further

Thank you for looking into this! This is not the only board affected by capture-to-lvgl and capture looking different:

esp32_s3_eye:

#90428

[josuah]

+--------------+    +----------+    +-------------+    +----------------+
| image sensor |----| lvgl img |----| lvgl engine |----| display driver |
+--------------+    +----------+    +-------------+    +----------------+
camera raw data     declared as      draws overlay      passes the bytes
                    LVGL image       on top             to the driver

It looks like the image content is inconsistent with the overlay.

Regardless the number of inversions that happens at every level, for sure, the LVGL image is considered with a different type as the LVGL driver.

zephyr/samples/drivers/video/capture_to_lvgl/src/main.c

Line 177 in 322da1d

.header.cf = LV_COLOR_FORMAT_NATIVE,

Maybe setting this to a different value (LV_COLOR_FORMAT_NATIVE_REVERSED?) would work.

Also, it seems like like... LV_COLOR_16_SWAP disappeared? :')

• Changes in master (v9 development) lvgl/lvgl#4011

zephyr/west.yml

Lines 304 to 306 in 322da1d

	- name: lvgl
	revision: b03edc8e6282a963cd312cd0b409eb5ce263ea75
	path: modules/lib/gui/lvgl

https://github.com/zephyrproject-rtos/lvgl/blob/b03edc8e6282a963cd312cd0b409eb5ce263ea75/lv_version.h

So v9.3.0... Let's ask #lvgl on the chat just in case...