RE: Simple "Hello World" lvgl label repeating when upgrading from 2.9.1 to 3.0.1

lcj — Wed, 27 Aug 2025 11:19:59 GMT

CONFIG_LV_CONF_MINIMAL=y caused it.

RE: Simple "Hello World" lvgl label repeating when upgrading from 2.9.1 to 3.0.1

lcj — Sat, 23 Aug 2025 16:19:41 GMT

When I do what you recommend:

            mipi-mode = MIPI_DBI_MODE_SPI_4WIRE;

I get an error on build:

-- Found devicetree overlay: djboard_nrf5340_cpuapp_310.overlay
devicetree error: /Users/xxxxxxxxx/Projects/GitHub/xxxxxxxxx/pcb1_lvgl/boards/ew/djboard/djboard_nrf5340_cpuapp.dts:57 (column 25): parse error: malformed value
CMake Error at /opt/nordic/ncs/v3.1.0/zephyr/cmake/modules/dts.cmake:306 (execute_process):
  execute_process failed command indexes:

line 57 is the line in the dts. If I convert it back to what worked in 2.9.1:

mipi-mode = <MIPI_DBI_MODE_SPI_4WIRE>;

I get this error:

devicetree.dtlib.DTError: expected property 'mipi-mode' on /mipi_dbi/st7789v@0 in /opt/nordic/ncs/v3.1.0/zephyr/misc/empty_file.c to be assigned with 'mipi-mode = "string";', not 'mipi-mode = < 0x2 >;'

Which is why I created a string with it. This should map to something Zephyr expects, I think.

Here is all the code. Again, this worked in 2.9.1:

#include <zephyr/kernel.h>
#include <zephyr/device.h>
#include <zephyr/drivers/display.h>
#include <zephyr/pm/device.h>
#include <zephyr/drivers/pwm.h>
#include <zephyr/drivers/gpio.h>
#include <zephyr/logging/log.h>
#include <stdio.h>
#include <app_version.h>
#include <lvgl.h>

LOG_MODULE_REGISTER(app, LOG_LEVEL_DBG);

int count = 0;

// BACKLIGHT MANAGER CODE
#define PWM_LED0    DT_ALIAS(pwm_led0)
static const struct pwm_dt_spec pwm_led0 = PWM_DT_SPEC_GET(PWM_LED0);

int backlight_manager_init(void) 
{

	LOG_DBG("Starting backlight PWM");

		
	if (!pwm_is_ready_dt(&pwm_led0)) {
		LOG_ERR("Error: PWM device %s is not ready", pwm_led0.dev->name);
		return -1;
	}

    return 0;

}

static void set_pwm(const struct pwm_dt_spec *pwmdev, uint8_t percent) {

	LOG_DBG("Setting PWM to %d%%", percent);

	int ret;
	uint32_t step = pwmdev->period / 100;
	uint32_t pulse_width = step * percent;

	if (!device_is_ready(pwmdev->dev)) {
		LOG_ERR("PWM device not ready");
		return;
	}

	ret = pwm_set_pulse_dt(pwmdev, pulse_width);
	if (ret < 0) {
		LOG_ERR("Failed to set pulse width: %i", ret);
		return;
	}
}

void backlight_manager_wake()
{
    set_pwm(&pwm_led0, 100); 
    //set_pwm(&backlight_spec, 1);
}


void backlight_manager_sleep()
{
    set_pwm(&pwm_led0, 0);
}

// DISPLAY MANAGER CODE
static const struct device *display_dev  = DEVICE_DT_GET(DT_CHOSEN(zephyr_display));

int display_manager_init(void) 
{
    LOG_DBG("Initializing display manager");
	if (!device_is_ready(display_dev)) {
		LOG_ERR("Device not ready, aborting test");
		return 0;
	}

    display_blanking_off(display_dev);

    return 0;
}

// VOLTAGE CODE
int change_gpio_voltage(uint32_t target_voltage)
{
    int err = 0;
    
    uint32_t regout = NRF_UICR->VREGHVOUT;
    LOG_INF("change_gpio_voltage: REGOUT = 0x%08x", regout);
    LOG_INF("change_gpio_voltage: target voltage is %d", target_voltage);    
    if ((regout & UICR_VREGHVOUT_VREGHVOUT_Msk)  != target_voltage) {
        LOG_INF("Target voltage not set. Configuring");

        // Set NVMC in write mode:
        NRF_NVMC->CONFIG = NVMC_CONFIG_WEN_Wen << NVMC_CONFIG_WEN_Pos;
        while (NRF_NVMC->CONFIG != NVMC_CONFIG_WEN_Wen << NVMC_CONFIG_WEN_Pos) {
            // Wait...
        }

        // Write the actual UICR Register:
        NRF_UICR->VREGHVOUT = (target_voltage | ~UICR_VREGHVOUT_VREGHVOUT_Msk);
        while (NRF_NVMC->READY == NVMC_READY_READY_Busy) {
            // Wait...
        }

        // Set NVMC back in read mode:
        NRF_NVMC->CONFIG = NVMC_CONFIG_WEN_Ren << NVMC_CONFIG_WEN_Pos;
        while (NRF_NVMC->CONFIG != NVMC_CONFIG_WEN_Ren << NVMC_CONFIG_WEN_Pos) {
            // Wait...
        }
        // Check whether it was set successfully:
        if ((NRF_UICR->VREGHVOUT & UICR_VREGHVOUT_VREGHVOUT_Msk) != target_voltage) {
            err = 0;
        }
        // Reset if success. Config will remain on future reboots.
        if (err == 0) {
            NVIC_SystemReset();
        }
    } else {
        LOG_INF("Target voltage already set. No action needed.");
        err = 0;
    }
    return err;

}

// SCREEN HELLO WORLD CODE
static  lv_obj_t *scr_home;

int screen_helloworld_init()
{
	LOG_DBG("Creating home screen");

	scr_home = lv_obj_create(NULL);
	// Used this function as it automatically deletes previous screen.
	// Should work as you did also I think. But have not used lv_scr_load_xxx before
	//lv_screen_load_anim(scr_home, LV_SCR_LOAD_ANIM_NONE, 0, 0, true);
	lv_screen_load(scr_home);

	lv_obj_t *hello_world_label;

	lv_obj_set_style_bg_color(lv_scr_act(), lv_palette_main(LV_PALETTE_GREEN), LV_PART_MAIN);
	lv_obj_set_style_text_color(lv_scr_act(), lv_color_white(), LV_PART_MAIN);

	hello_world_label = lv_label_create(lv_scr_act());

	lv_label_set_text(hello_world_label, "Hello World!");
	lv_obj_align(hello_world_label, LV_ALIGN_CENTER, 0, 0);
	lv_obj_set_style_text_font(hello_world_label, &lv_font_montserrat_16, LV_PART_MAIN);

	return 0;
}

// SCREEN HELLO WORLD 2CODE
static  lv_obj_t *scr_home2;

int screen_helloworld2_init()
{
	LOG_DBG("Creating home screen");

	scr_home2 = lv_obj_create(NULL);
	// Used this function as it automatically deletes previous screen.
	// Should work as you did also I think. But have not used lv_scr_load_xxx before
	lv_screen_load_anim(scr_home2, LV_SCR_LOAD_ANIM_NONE, 0, 0, true);
	//lv_screen_load(scr_home2);

	lv_obj_t *hello_world_label;

	lv_obj_set_style_bg_color(lv_scr_act(), lv_palette_main(LV_PALETTE_GREEN), LV_PART_MAIN);
	lv_obj_set_style_text_color(lv_scr_act(), lv_color_white(), LV_PART_MAIN);

	hello_world_label = lv_label_create(lv_scr_act());

	lv_label_set_text(hello_world_label, "Hello World 2!");
	lv_obj_align(hello_world_label, LV_ALIGN_CENTER, 0, 0);
	lv_obj_set_style_text_font(hello_world_label, &lv_font_montserrat_16, LV_PART_MAIN);

	return 0;
}


int main(void)
{
    LOG_DBG("Hello World! %s (%s)", CONFIG_BOARD, APP_VERSION_EXTENDED_STRING);
	change_gpio_voltage(UICR_VREGHVOUT_VREGHVOUT_3V0);
	display_manager_init();
	backlight_manager_init();
	screen_helloworld_init();
	backlight_manager_wake();
	while (count < 100) {
		count++;
		LOG_DBG("looping %d", count);
		if (count == 50) {
			LOG_DBG("Let's load screen 2");
			screen_helloworld2_init();
		}
		k_sleep(K_MSEC(1000));
		lv_timer_handler();
	}
	backlight_manager_sleep();
	return 0;
}

I changed it and added a "Hello World 2" screen. At first my screen looked like this:

With the change it looked like this:

RE: Simple "Hello World" lvgl label repeating when upgrading from 2.9.1 to 3.0.1

Kazi Afroza Sultana — Fri, 22 Aug 2025 08:56:44 GMT

Hello,

Did you call screen_helloworld_init() in your code apart from once elsewhere in the project? You can review your code to ensure you are not creating or loading the screen or label multiple times as display is showing ''Hello World'' 3 times. Check the main function and lv_screen_load_anim() to ensure that you are not reloading the same screen multiple times without clearing previous objects.

DTS looks ok. One thing you need to change for mipi-mode. mipi-mode is as an integer, not a string. You need to replace this

mipi-mode = "MIPI_DBI_MODE_SPI_4WIRE";

mipi-mode = MIPI_DBI_MODE_SPI_4WIRE;

Thanks.

Kazi