I am trying to display the time on a OLED display using the RTC and I can get it to work but I keep getting a warning. I know there is a better way and was hoping someone could enlighten me as to what I should be doing.

[JWire.1]

Hello I am very new to c programming and embedded design. I know there is a right way to do what I am trying to accomplish. I seem to be doing it the wrong way even though my code still "works"

I am getting warnings on a couple lines of code. Line 51 and 53 of this code snippet.

the warning is "pointer targets in passing argument 1 of 'SSD1306_Puts' differ in signedness [-Wpointer-sign]

I can't include all my code because it is saying my post is too long so I have tried to include all the relevant information.

I

/* USER CODE BEGIN PTD */
 
/* Buffers used to display Time and Date */
uint8_t aShowTime[50] = {0};
uint8_t aShowDate[50] = {0};
 
 
 
 
 
 
/**
  * @brief  Display the current time and date.
  * @param  showtime : pointer to buffer
  * @param  showdate : pointer to buffer
  * @retval None
  */
static void RTC_CalendarUpdate(uint8_t *showtime, uint8_t *showdate)
{
 
  RTC_DateTypeDef sdatestructureget;
  RTC_TimeTypeDef stimestructureget;
 
  /* Get the RTC current Time */
  if (HAL_RTC_GetTime(&hrtc, &stimestructureget, RTC_FORMAT_BIN) != HAL_OK)
  {
    /* HAL Error */
    Error_Handler();
  }
 
  /* Get the RTC current Date */
  if (HAL_RTC_GetDate(&hrtc, &sdatestructureget, RTC_FORMAT_BIN) != HAL_OK)
  {
    /* HAL Error */
    Error_Handler();
  }
 
  /* Display time Format : hh:mm:ss */
  sprintf((char *)showtime, "%02d:%02d:%02d", stimestructureget.Hours, stimestructureget.Minutes, stimestructureget.Seconds);
  /* Display date Format : mm-dd-yy */
  sprintf((char *)showdate, "%02d-%02d-%02d", sdatestructureget.Month, sdatestructureget.Date, 2000 + sdatestructureget.Year);
}
 
 
 
void display_time (void)
{
	 RTC_CalendarUpdate(aShowTime, aShowDate);
 
	  SSD1306_GotoXY(20, 0);
	  SSD1306_Puts(aShowTime, &Font_11x18, 1);
	  SSD1306_GotoXY(10, 30);
	  SSD1306_Puts(aShowDate, &Font_11x18, 1);
	  SSD1306_UpdateScreen();
 
 
 
}

[TDK · Accepted solution]

You can convert your pointers to unsigned bytes to pointers to signed bytes like this:

	  SSD1306_Puts((char *) aShowTime, &Font_11x18, 1);
	  SSD1306_GotoXY(10, 30);
	  SSD1306_Puts((char *) aShowDate, &Font_11x18, 1);

> I can't include all my code because it is saying my post is too long so I have tried to include all the relevant information.

For future reference, you can attach a file to your post if you want to include the code. No need to do so here.

[JWire.1]

Thank you for the info!

It works and complies with no warnings now.

Appreciate the help.