How to Display a simple input value to a label text value

How-to
1

Important: unclear posts may not receive useful answers.

Before posting

  • Get familiar with Markdown to format and structure your post
  • Be sure to update lvgl from the latest version from the master branch.
  • Be sure you have checked the FAQ and read the relevant part of the documentation.
  • If applicable use the Simulator to eliminate hardware related issues.

Delete this section if you read and applied the mentioned points.

Description

What MCU/Processor/Board and compiler are you using?

What LVGL version are you using? 8

What do you want to achieve? Create and update/refresh a label text value from an input (RTC).

What have you tried so far? Adding code to ‘ui_Screen1.c’.

Code to reproduce

Hi, I have successfully managed to add a internal RTC time value to a simple text label, the problem is this value doesn’t seem to update how can I do this? Do I create some kind of event or do I need to refresh the label text value? Thanks

Here is current code ‘ui_Screen1.c’:-

extern RTC_HandleTypeDef hrtc;
RTC_TimeTypeDef sTime = {0};
RTC_DateTypeDef sDate = {0};

void ui_Screen1_screen_init(void)
{
ui_Screen1 = lv_obj_create(NULL);
lv_obj_clear_flag( ui_Screen1, LV_OBJ_FLAG_SCROLLABLE ); /// Flags

ui_Label1 = lv_label_create(ui_Screen1);
lv_obj_set_width( ui_Label1, LV_SIZE_CONTENT); /// 1
lv_obj_set_height( ui_Label1, LV_SIZE_CONTENT); /// 1
lv_obj_set_x( ui_Label1, -94 );
lv_obj_set_y( ui_Label1, -99 );
lv_obj_set_align( ui_Label1, LV_ALIGN_CENTER );

HAL_RTC_GetTime(&hrtc, &sTime, RTC_FORMAT_BIN);
*lv_label_set_text_fmt(ui_Label1, “%02d:%02d:%02d”, sTime.Hours,sTime.Minutes,sTime.Seconds);
*}

2

Create lv_timer and refresh every sec.

3

Hi Marian, is this done in the ‘main.c’ file ‘while (1)’ loop? If so are there any instructions for this? Thanks

4

In setup

lv_timer_t * timer = lv_timer_create(callbackperiod1s, 1000,  NULL);

and callback

void callbackperiod1s(lv_timer_t * timer)
{
...get time struct my example use esp32 getlocaltime
  strftime(timeStringBuff, sizeof(timeStringBuff), "%H:%M:%S", &tv_now);
lv_label_set_text(ui_LabelTime,timeStringBuff);
}
1 Like
5

Hi, the closest I came to your advice loads the time but it stop refreshing after 1s and freezes? I Show below:-

Blockquote
int main(void)
{

/* USER CODE BEGIN 1 */


void callbackperiod1s(lv_timer_t * timer)
	  {

     HAL_StatusTypeDef res;
     RTC_TimeTypeDef time;


	      res = HAL_RTC_GetTime(&hrtc, &time, RTC_FORMAT_BIN);
	      if(res != HAL_OK) {

	          return;
	      }

	    char tmp[50];
	    snprintf(tmp, sizeof(tmp), "%02d:%02d:%02d", time.Hours, time.Minutes, time.Seconds);
	  	lv_label_set_text_fmt(ui_Label1,tmp);
	  }

/* USER CODE END 1 */

/* MCU Configuration--------------------------------------------------------*/

/* Reset of all peripherals, Initializes the Flash interface and the Systick. */
HAL_Init();

/* USER CODE BEGIN Init /
MX_DMA_Init();
/ USER CODE END Init */

/* Configure the system clock */
SystemClock_Config();

/* USER CODE BEGIN SysInit */

/* USER CODE END SysInit */

/* Initialize all configured peripherals /
MX_GPIO_Init();
MX_DMA_Init();
MX_CRC_Init();
MX_SPI4_Init();
MX_RTC_Init();
/ USER CODE BEGIN 2 */
//lv_init();
//display_init(3);

/* USER CODE END 2 */

/* Infinite loop /
/ USER CODE BEGIN WHILE */
lv_init();
Display_init(3);
// ST7789_Init();
HAL_Delay (500);

ui_init();
lv_timer_t * timer = lv_timer_create(callbackperiod1s, 500, NULL);
lv_timer_set_repeat_count(timer, -1);

while (1)
{
/* USER CODE END WHILE */

/* USER CODE BEGIN 3 */

  HAL_Delay(1);
  lv_task_handler();
  lv_tick_inc(1);
  lv_timer_handler();
  HAL_Delay(5);

}
/* USER CODE END 3 */
}

6

I mean your while 1 is ugly. Too i dont understand placement void inside main
… read lvgl docu for implement it. Set up a project — LVGL documentation

too remove _fmt from

lv_label_set_text_fmt(ui_Label1,tmp);
7

Hi Marian, Thanks for the advice I changed the ‘lv_label_set_text_fmt(ui_Label1,tmp);’ to ‘lv_label_set_text(ui_Label1,tmp);’ and it still doesn’t refresh the value on the TFT screen? Am I missing something? if anyone has any example code of a variable text value updating on the screen it would be appreciated!

8

your while is trouble no update func. Read docu and do what is descripted.
Debug your while is block or running