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Display string on NUCLEO-U575ZI-Q by 16x2 LCD with I2c driver

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SMusc.1
Associate III

‎2025-04-14 2:03 AM - last edited on ‎2025-04-14 3:16 AM by

Good morning, I have been trying to make simple characters appear on the 16x2 character LCD display for a while now and I am using a U575ZI-Q core board. I have followed many tutorials but none of them have allowed me to display a simple line of text on the display.
I would like to point out that with the Arduino board I have no difficulty displaying simple characters like hello word, but with this board I can't. I am using two libraries in a row and the following code in the main.c file. Could you help me? The 16x2 LCD display has the I2C driver with a PCF8574T integrated circuit.

 

/* USER CODE BEGIN Header */

/**

******************************************************************************

* @file : main.c

* @brief : Main program body

******************************************************************************

* @attention

*

* Copyright (c) 2025 STMicroelectronics.

* All rights reserved.

*

* This software is licensed under terms that can be found in the LICENSE file

* in the root directory of this software component.

* If no LICENSE file comes with this software, it is provided AS-IS.

*

******************************************************************************

*/

/* USER CODE END Header */

/* Includes ------------------------------------------------------------------*/

#include "main.h"

#include "i2c.h"

#include "memorymap.h"

#include "gpio.h"



/* Private includes ----------------------------------------------------------*/

/* USER CODE BEGIN Includes */

#include "i2c_lcd.h"

/* USER CODE END Includes */



/* Private typedef -----------------------------------------------------------*/

/* USER CODE BEGIN PTD */



/* USER CODE END PTD */



/* Private define ------------------------------------------------------------*/

/* USER CODE BEGIN PD */



/* USER CODE END PD */



/* Private macro -------------------------------------------------------------*/

/* USER CODE BEGIN PM */



/* USER CODE END PM */



/* Private variables ---------------------------------------------------------*/



/* USER CODE BEGIN PV */



/* USER CODE END PV */



/* Private function prototypes -----------------------------------------------*/

void SystemClock_Config(void);

/* USER CODE BEGIN PFP */



/* USER CODE END PFP */



/* Private user code ---------------------------------------------------------*/

/* USER CODE BEGIN 0 */



/* USER CODE END 0 */



/**

* @brief The application entry point.

* @retval int

*/

int main(void)

{

/* USER CODE BEGIN 1 */



/* USER CODE END 1 */



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



/* Reset of all peripherals, Initializes the Flash interface and the Systick. */

HAL_Init();



/* USER CODE BEGIN 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_MEMORYMAP_Init();

MX_I2C1_Init();

/* USER CODE BEGIN 2 */

lcd_init();

/* USER CODE END 2 */



/* Infinite loop */

/* USER CODE BEGIN WHILE */

while (1)

{

/* USER CODE END WHILE */



/* USER CODE BEGIN 3 */

lcd_put_cursor(0,0);

lcd_send_string("hello word_1");

lcd_put_cursor(1,0);

lcd_send_string("hello word_2");

HAL_Delay(50);

}

/* USER CODE END 3 */

}



/**

* @brief System Clock Configuration

* @retval None

*/

void SystemClock_Config(void)

{

RCC_OscInitTypeDef RCC_OscInitStruct = {0};

RCC_ClkInitTypeDef RCC_ClkInitStruct = {0};



/** Configure the main internal regulator output voltage

*/

if (HAL_PWREx_ControlVoltageScaling(PWR_REGULATOR_VOLTAGE_SCALE1) != HAL_OK)

{

Error_Handler();

}



/** Initializes the CPU, AHB and APB buses clocks

*/

RCC_OscInitStruct.OscillatorType = RCC_OSCILLATORTYPE_MSI;

RCC_OscInitStruct.MSIState = RCC_MSI_ON;

RCC_OscInitStruct.MSICalibrationValue = RCC_MSICALIBRATION_DEFAULT;

RCC_OscInitStruct.MSIClockRange = RCC_MSIRANGE_0;

RCC_OscInitStruct.PLL.PLLState = RCC_PLL_ON;

RCC_OscInitStruct.PLL.PLLSource = RCC_PLLSOURCE_MSI;

RCC_OscInitStruct.PLL.PLLMBOOST = RCC_PLLMBOOST_DIV4;

RCC_OscInitStruct.PLL.PLLM = 3;

RCC_OscInitStruct.PLL.PLLN = 8;

RCC_OscInitStruct.PLL.PLLP = 2;

RCC_OscInitStruct.PLL.PLLQ = 2;

RCC_OscInitStruct.PLL.PLLR = 1;

RCC_OscInitStruct.PLL.PLLRGE = RCC_PLLVCIRANGE_1;

RCC_OscInitStruct.PLL.PLLFRACN = 0;

if (HAL_RCC_OscConfig(&RCC_OscInitStruct) != HAL_OK)

{

Error_Handler();

}



/** Initializes the CPU, AHB and APB buses clocks

*/

RCC_ClkInitStruct.ClockType = RCC_CLOCKTYPE_HCLK|RCC_CLOCKTYPE_SYSCLK

|RCC_CLOCKTYPE_PCLK1|RCC_CLOCKTYPE_PCLK2

|RCC_CLOCKTYPE_PCLK3;

RCC_ClkInitStruct.SYSCLKSource = RCC_SYSCLKSOURCE_PLLCLK;

RCC_ClkInitStruct.AHBCLKDivider = RCC_SYSCLK_DIV8;

RCC_ClkInitStruct.APB1CLKDivider = RCC_HCLK_DIV1;

RCC_ClkInitStruct.APB2CLKDivider = RCC_HCLK_DIV1;

RCC_ClkInitStruct.APB3CLKDivider = RCC_HCLK_DIV1;



if (HAL_RCC_ClockConfig(&RCC_ClkInitStruct, FLASH_LATENCY_0) != HAL_OK)

{

Error_Handler();

}

}



/* USER CODE BEGIN 4 */



/* USER CODE END 4 */



/**

* @brief This function is executed in case of error occurrence.

* @retval None

*/

void Error_Handler(void)

{

/* USER CODE BEGIN Error_Handler_Debug */

/* User can add his own implementation to report the HAL error return state */

__disable_irq();

while (1)

{

}

/* USER CODE END Error_Handler_Debug */

}



#ifdef USE_FULL_ASSERT

/**

* @brief Reports the name of the source file and the source line number

* where the assert_param error has occurred.

*  file: pointer to the source file name

*  line: assert_param error line source number

* @retval None

*/

void assert_failed(uint8_t *file, uint32_t line)

{

/* USER CODE BEGIN 6 */

/* User can add his own implementation to report the file name and line number,

ex: printf("Wrong parameters value: file %s on line %d\r\n", file, line) */

/* USER CODE END 6 */

}

#endif /* USE_FULL_ASSERT */
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mƎALLEm
ST Employee
In response to SMusc.1

‎2025-04-14 5:00 AM - edited ‎2025-04-14 5:01 AM

In that case you need to check

Your hardware:

1- did you connect pull up resistors on both lines SDA and SCL?

2- Are you sure you did connect the I2C lines of the LCD to the correct 12C pins of the STM32?

Software:

1- Did you configure the right GPIOs pins that will be connected to the LCD in CubeMx?

 

To give better visibility on the answered topics, please click on "Accept as Solution" on the reply which solved your issue or answered your question.

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mƎALLEm
ST Employee

‎2025-04-14 3:13 AM - edited ‎2025-04-14 3:13 AM

Hello,

Please kindly use </> button to share a code. Please refer to this post. I'm editing your post.

Thank you for you understanding.

To give better visibility on the answered topics, please click on "Accept as Solution" on the reply which solved your issue or answered your question.
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SMusc.1
Associate III

‎2025-04-14 3:18 AM 

/* USER CODE BEGIN Header */
/**
  ******************************************************************************
  * @file           : main.c
  * @brief          : Main program body
  ******************************************************************************
  * @attention
  *
  * Copyright (c) 2025 STMicroelectronics.
  * All rights reserved.
  *
  * This software is licensed under terms that can be found in the LICENSE file
  * in the root directory of this software component.
  * If no LICENSE file comes with this software, it is provided AS-IS.
  *
  ******************************************************************************
  */
/* USER CODE END Header */
/* Includes ------------------------------------------------------------------*/
#include "main.h"
#include "i2c.h"
#include "memorymap.h"
#include "gpio.h"

/* Private includes ----------------------------------------------------------*/
/* USER CODE BEGIN Includes */
#include "i2c_lcd.h"
/* USER CODE END Includes */

/* Private typedef -----------------------------------------------------------*/
/* USER CODE BEGIN PTD */

/* USER CODE END PTD */

/* Private define ------------------------------------------------------------*/
/* USER CODE BEGIN PD */

/* USER CODE END PD */

/* Private macro -------------------------------------------------------------*/
/* USER CODE BEGIN PM */

/* USER CODE END PM */

/* Private variables ---------------------------------------------------------*/

/* USER CODE BEGIN PV */

/* USER CODE END PV */

/* Private function prototypes -----------------------------------------------*/
void SystemClock_Config(void);
/* USER CODE BEGIN PFP */

/* USER CODE END PFP */

/* Private user code ---------------------------------------------------------*/
/* USER CODE BEGIN 0 */

/* USER CODE END 0 */

/**
  * @brief  The application entry point.
  * @retval int
  */
int main(void)
{
  /* USER CODE BEGIN 1 */

  /* USER CODE END 1 */

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

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

  /* USER CODE BEGIN 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_MEMORYMAP_Init();
  MX_I2C1_Init();
  /* USER CODE BEGIN 2 */
  lcd_init();
  /* USER CODE END 2 */

  /* Infinite loop */
  /* USER CODE BEGIN WHILE */
  while (1)
  {
    /* USER CODE END WHILE */

    /* USER CODE BEGIN 3 */
	  lcd_put_cursor(0,0);
	  lcd_send_string("ciao mondo");
	  lcd_put_cursor(1,0);
	  lcd_send_string("ricchio");
	  HAL_Delay(50);
  }
  /* USER CODE END 3 */
}

/**
  * @brief System Clock Configuration
  * @retval None
  */
void SystemClock_Config(void)
{
  RCC_OscInitTypeDef RCC_OscInitStruct = {0};
  RCC_ClkInitTypeDef RCC_ClkInitStruct = {0};

  /** Configure the main internal regulator output voltage
  */
  if (HAL_PWREx_ControlVoltageScaling(PWR_REGULATOR_VOLTAGE_SCALE1) != HAL_OK)
  {
    Error_Handler();
  }

  /** Initializes the CPU, AHB and APB buses clocks
  */
  RCC_OscInitStruct.OscillatorType = RCC_OSCILLATORTYPE_MSI;
  RCC_OscInitStruct.MSIState = RCC_MSI_ON;
  RCC_OscInitStruct.MSICalibrationValue = RCC_MSICALIBRATION_DEFAULT;
  RCC_OscInitStruct.MSIClockRange = RCC_MSIRANGE_0;
  RCC_OscInitStruct.PLL.PLLState = RCC_PLL_ON;
  RCC_OscInitStruct.PLL.PLLSource = RCC_PLLSOURCE_MSI;
  RCC_OscInitStruct.PLL.PLLMBOOST = RCC_PLLMBOOST_DIV4;
  RCC_OscInitStruct.PLL.PLLM = 3;
  RCC_OscInitStruct.PLL.PLLN = 8;
  RCC_OscInitStruct.PLL.PLLP = 2;
  RCC_OscInitStruct.PLL.PLLQ = 2;
  RCC_OscInitStruct.PLL.PLLR = 1;
  RCC_OscInitStruct.PLL.PLLRGE = RCC_PLLVCIRANGE_1;
  RCC_OscInitStruct.PLL.PLLFRACN = 0;
  if (HAL_RCC_OscConfig(&RCC_OscInitStruct) != HAL_OK)
  {
    Error_Handler();
  }

  /** Initializes the CPU, AHB and APB buses clocks
  */
  RCC_ClkInitStruct.ClockType = RCC_CLOCKTYPE_HCLK|RCC_CLOCKTYPE_SYSCLK
                              |RCC_CLOCKTYPE_PCLK1|RCC_CLOCKTYPE_PCLK2
                              |RCC_CLOCKTYPE_PCLK3;
  RCC_ClkInitStruct.SYSCLKSource = RCC_SYSCLKSOURCE_PLLCLK;
  RCC_ClkInitStruct.AHBCLKDivider = RCC_SYSCLK_DIV8;
  RCC_ClkInitStruct.APB1CLKDivider = RCC_HCLK_DIV1;
  RCC_ClkInitStruct.APB2CLKDivider = RCC_HCLK_DIV1;
  RCC_ClkInitStruct.APB3CLKDivider = RCC_HCLK_DIV1;

  if (HAL_RCC_ClockConfig(&RCC_ClkInitStruct, FLASH_LATENCY_0) != HAL_OK)
  {
    Error_Handler();
  }
}

/* USER CODE BEGIN 4 */

/* USER CODE END 4 */

/**
  * @brief  This function is executed in case of error occurrence.
  * @retval None
  */
void Error_Handler(void)
{
  /* USER CODE BEGIN Error_Handler_Debug */
  /* User can add his own implementation to report the HAL error return state */
  __disable_irq();
  while (1)
  {
  }
  /* USER CODE END Error_Handler_Debug */
}

#ifdef  USE_FULL_ASSERT
/**
  * @brief  Reports the name of the source file and the source line number
  *         where the assert_param error has occurred.
  * @PAram  file: pointer to the source file name
  * @PAram  line: assert_param error line source number
  * @retval None
  */
void assert_failed(uint8_t *file, uint32_t line)
{
  /* USER CODE BEGIN 6 */
  /* User can add his own implementation to report the file name and line number,
     ex: printf("Wrong parameters value: file %s on line %d\r\n", file, line) */
  /* USER CODE END 6 */
}
#endif /* USE_FULL_ASSERT */

 

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SMusc.1
Associate III
In response to mƎALLEm

‎2025-04-14 3:19 AM

Hi, sure, belo the full code

 

/* USER CODE BEGIN Header */
/**
  ******************************************************************************
  * @file           : main.c
  * @brief          : Main program body
  ******************************************************************************
  * @attention
  *
  * Copyright (c) 2025 STMicroelectronics.
  * All rights reserved.
  *
  * This software is licensed under terms that can be found in the LICENSE file
  * in the root directory of this software component.
  * If no LICENSE file comes with this software, it is provided AS-IS.
  *
  ******************************************************************************
  */
/* USER CODE END Header */
/* Includes ------------------------------------------------------------------*/
#include "main.h"
#include "i2c.h"
#include "memorymap.h"
#include "gpio.h"

/* Private includes ----------------------------------------------------------*/
/* USER CODE BEGIN Includes */
#include "i2c_lcd.h"
/* USER CODE END Includes */

/* Private typedef -----------------------------------------------------------*/
/* USER CODE BEGIN PTD */

/* USER CODE END PTD */

/* Private define ------------------------------------------------------------*/
/* USER CODE BEGIN PD */

/* USER CODE END PD */

/* Private macro -------------------------------------------------------------*/
/* USER CODE BEGIN PM */

/* USER CODE END PM */

/* Private variables ---------------------------------------------------------*/

/* USER CODE BEGIN PV */

/* USER CODE END PV */

/* Private function prototypes -----------------------------------------------*/
void SystemClock_Config(void);
/* USER CODE BEGIN PFP */

/* USER CODE END PFP */

/* Private user code ---------------------------------------------------------*/
/* USER CODE BEGIN 0 */

/* USER CODE END 0 */

/**
  * @brief  The application entry point.
  * @retval int
  */
int main(void)
{
  /* USER CODE BEGIN 1 */

  /* USER CODE END 1 */

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

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

  /* USER CODE BEGIN 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_MEMORYMAP_Init();
  MX_I2C1_Init();
  /* USER CODE BEGIN 2 */
  lcd_init();
  /* USER CODE END 2 */

  /* Infinite loop */
  /* USER CODE BEGIN WHILE */
  while (1)
  {
    /* USER CODE END WHILE */

    /* USER CODE BEGIN 3 */
	  lcd_put_cursor(0,0);
	  lcd_send_string("ciao mondo");
	  lcd_put_cursor(1,0);
	  lcd_send_string("ricchio");
	  HAL_Delay(50);
  }
  /* USER CODE END 3 */
}

/**
  * @brief System Clock Configuration
  * @retval None
  */
void SystemClock_Config(void)
{
  RCC_OscInitTypeDef RCC_OscInitStruct = {0};
  RCC_ClkInitTypeDef RCC_ClkInitStruct = {0};

  /** Configure the main internal regulator output voltage
  */
  if (HAL_PWREx_ControlVoltageScaling(PWR_REGULATOR_VOLTAGE_SCALE1) != HAL_OK)
  {
    Error_Handler();
  }

  /** Initializes the CPU, AHB and APB buses clocks
  */
  RCC_OscInitStruct.OscillatorType = RCC_OSCILLATORTYPE_MSI;
  RCC_OscInitStruct.MSIState = RCC_MSI_ON;
  RCC_OscInitStruct.MSICalibrationValue = RCC_MSICALIBRATION_DEFAULT;
  RCC_OscInitStruct.MSIClockRange = RCC_MSIRANGE_0;
  RCC_OscInitStruct.PLL.PLLState = RCC_PLL_ON;
  RCC_OscInitStruct.PLL.PLLSource = RCC_PLLSOURCE_MSI;
  RCC_OscInitStruct.PLL.PLLMBOOST = RCC_PLLMBOOST_DIV4;
  RCC_OscInitStruct.PLL.PLLM = 3;
  RCC_OscInitStruct.PLL.PLLN = 8;
  RCC_OscInitStruct.PLL.PLLP = 2;
  RCC_OscInitStruct.PLL.PLLQ = 2;
  RCC_OscInitStruct.PLL.PLLR = 1;
  RCC_OscInitStruct.PLL.PLLRGE = RCC_PLLVCIRANGE_1;
  RCC_OscInitStruct.PLL.PLLFRACN = 0;
  if (HAL_RCC_OscConfig(&RCC_OscInitStruct) != HAL_OK)
  {
    Error_Handler();
  }

  /** Initializes the CPU, AHB and APB buses clocks
  */
  RCC_ClkInitStruct.ClockType = RCC_CLOCKTYPE_HCLK|RCC_CLOCKTYPE_SYSCLK
                              |RCC_CLOCKTYPE_PCLK1|RCC_CLOCKTYPE_PCLK2
                              |RCC_CLOCKTYPE_PCLK3;
  RCC_ClkInitStruct.SYSCLKSource = RCC_SYSCLKSOURCE_PLLCLK;
  RCC_ClkInitStruct.AHBCLKDivider = RCC_SYSCLK_DIV8;
  RCC_ClkInitStruct.APB1CLKDivider = RCC_HCLK_DIV1;
  RCC_ClkInitStruct.APB2CLKDivider = RCC_HCLK_DIV1;
  RCC_ClkInitStruct.APB3CLKDivider = RCC_HCLK_DIV1;

  if (HAL_RCC_ClockConfig(&RCC_ClkInitStruct, FLASH_LATENCY_0) != HAL_OK)
  {
    Error_Handler();
  }
}

/* USER CODE BEGIN 4 */

/* USER CODE END 4 */

/**
  * @brief  This function is executed in case of error occurrence.
  * @retval None
  */
void Error_Handler(void)
{
  /* USER CODE BEGIN Error_Handler_Debug */
  /* User can add his own implementation to report the HAL error return state */
  __disable_irq();
  while (1)
  {
  }
  /* USER CODE END Error_Handler_Debug */
}

#ifdef  USE_FULL_ASSERT
/**
  * @brief  Reports the name of the source file and the source line number
  *         where the assert_param error has occurred.
  * @PAram  file: pointer to the source file name
  * @PAram  line: assert_param error line source number
  * @retval None
  */
void assert_failed(uint8_t *file, uint32_t line)
{
  /* USER CODE BEGIN 6 */
  /* User can add his own implementation to report the file name and line number,
     ex: printf("Wrong parameters value: file %s on line %d\r\n", file, line) */
  /* USER CODE END 6 */
}
#endif /* USE_FULL_ASSERT */

 

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mƎALLEm
ST Employee

‎2025-04-14 3:19 AM

Now regarding your question, better to use an oscilloscope or a logic analyzer to see what happens on the i2c bus.

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SMusc.1
Associate III
In response to mƎALLEm

‎2025-04-14 4:53 AM

Hi, I checked just now also change some things in the setting in CUDE IDE but on both SCL and SDA channel nothing is showed. i am using digital scope Tektronics TDS2024B as attached picture (CH1 SCL and CH2 SDA).

In setting i write below parameters:

In clock configuration all peripheral of the clock are set to 16 MHz.

In the connectivity i am using I2C1 in fast mod (i checked in normal mode but that have no effect).

 

 

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mƎALLEm
ST Employee
In response to SMusc.1

‎2025-04-14 5:00 AM - edited ‎2025-04-14 5:01 AM

In that case you need to check

Your hardware:

1- did you connect pull up resistors on both lines SDA and SCL?

2- Are you sure you did connect the I2C lines of the LCD to the correct 12C pins of the STM32?

Software:

1- Did you configure the right GPIOs pins that will be connected to the LCD in CubeMx?

 

To give better visibility on the answered topics, please click on "Accept as Solution" on the reply which solved your issue or answered your question.
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SMusc.1
Associate III
In response to SMusc.1

‎2025-04-14 5:01 AM

Attached the last picture from digital scope by using a different GND point on the Nucle Board

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SMusc.1
Associate III
In response to mƎALLEm

‎2025-04-14 5:13 AM

Hi, regarding the pull up resistor i connected no resistors since in all tutorial saw in web no one did it and their LCD was showing some characters. The GPIO PINs are right and I chosen PA8 and PA9 as SCL and SDA. The N°2 question have no sense because from pin SCL and SDA nothing is showed. 

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mƎALLEm
ST Employee
In response to SMusc.1

‎2025-04-14 5:50 AM - edited ‎2025-04-14 6:26 AM

@SMusc.1 wrote:

Hi, regarding the pull up resistor i connected no resistors since in all tutorial saw in web no one did it and their LCD was showing some characters. 

You need to check that before going ahead. check if the pull up resistors on the I2C lines on the LCD board. You need to add them externally. This is elementary for I2C communication.

 

@SMusc.1 wrote:

 The N°2 question have no sense because from pin SCL and SDA nothing is showed. 

Sorry I didn't understand your comment here. I meant, you need to check if you connected the LCD I2C pins to the GPIO pins that you are planning to use. For example if you are using PA1 and PA2 make sure that the LCD is actually connected to PA1 and PA2 as well as your oscilloscope. That's it.

To give better visibility on the answered topics, please click on "Accept as Solution" on the reply which solved your issue or answered your question.
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