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May 27, 2024
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CRC calculation gives 32 bit number instead of 8 bit

  • May 27, 2024
  • 1 reply
  • 1089 views

Hello. I'm trying to obtain CRC value from CRC peripheral. It's supposed to give me 8 bit number. Instead it gives me 32 bit number. What am I doing wrong? Below is the code and program outputs.

 

/* USER CODE BEGIN Header */
/**
 ******************************************************************************
 * @file : main.c
 * @brief : Main program body
 ******************************************************************************
 * @attention
 *
 * Copyright (c) 2024 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"

/* Private includes ----------------------------------------------------------*/
/* USER CODE BEGIN Includes */

/* 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 ---------------------------------------------------------*/
CRC_HandleTypeDef hcrc;

UART_HandleTypeDef huart2;

/* USER CODE BEGIN PV */

/* USER CODE END PV */

/* Private function prototypes -----------------------------------------------*/
void SystemClock_Config(void);
static void MX_GPIO_Init(void);
static void MX_USART2_UART_Init(void);
static void MX_CRC_Init(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_USART2_UART_Init();
 MX_CRC_Init();
 /* USER CODE BEGIN 2 */

 uint8_t uart_buffer[4] = {0};
 uint32_t crc_input_arr[1];
 uint32_t crc_out = 0;

 /* USER CODE END 2 */

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

 /* USER CODE BEGIN 3 */
	HAL_UART_Receive(&huart2, uart_buffer, 4, HAL_MAX_DELAY);
	crc_input_arr[0] = \
	 (((uint32_t) uart_buffer[0]) << 24) | \
	 (((uint32_t) uart_buffer[1]) << 16) | \
	 (((uint32_t) uart_buffer[2]) << 8) | \
	 (((uint32_t) uart_buffer[3]));
	crc_out = HAL_CRC_Calculate(&hcrc, crc_input_arr, 4);
	HAL_UART_Transmit(&huart2, (uint8_t *)crc_out, 4, HAL_MAX_DELAY);
 }
 /* USER CODE END 3 */
}

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

 /** Initializes the RCC Oscillators according to the specified parameters
 * in the RCC_OscInitTypeDef structure.
 */
 RCC_OscInitStruct.OscillatorType = RCC_OSCILLATORTYPE_HSI;
 RCC_OscInitStruct.HSIState = RCC_HSI_ON;
 RCC_OscInitStruct.HSICalibrationValue = RCC_HSICALIBRATION_DEFAULT;
 RCC_OscInitStruct.PLL.PLLState = RCC_PLL_NONE;
 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_ClkInitStruct.SYSCLKSource = RCC_SYSCLKSOURCE_HSI;
 RCC_ClkInitStruct.AHBCLKDivider = RCC_SYSCLK_DIV1;
 RCC_ClkInitStruct.APB1CLKDivider = RCC_HCLK_DIV1;
 RCC_ClkInitStruct.APB2CLKDivider = RCC_HCLK_DIV1;

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

/**
 * @brief CRC Initialization Function
 * @PAram None
 * @retval None
 */
static void MX_CRC_Init(void)
{

 /* USER CODE BEGIN CRC_Init 0 */

 /* USER CODE END CRC_Init 0 */

 /* USER CODE BEGIN CRC_Init 1 */

 /* USER CODE END CRC_Init 1 */
 hcrc.Instance = CRC;
 hcrc.Init.DefaultPolynomialUse = DEFAULT_POLYNOMIAL_DISABLE;
 hcrc.Init.DefaultInitValueUse = DEFAULT_INIT_VALUE_DISABLE;
 hcrc.Init.GeneratingPolynomial = 7;
 hcrc.Init.CRCLength = CRC_POLYLENGTH_8B;
 hcrc.Init.InitValue = 0;
 hcrc.Init.InputDataInversionMode = CRC_INPUTDATA_INVERSION_BYTE;
 hcrc.Init.OutputDataInversionMode = CRC_OUTPUTDATA_INVERSION_DISABLE;
 hcrc.InputDataFormat = CRC_INPUTDATA_FORMAT_BYTES;
 if (HAL_CRC_Init(&hcrc) != HAL_OK)
 {
 Error_Handler();
 }
 /* USER CODE BEGIN CRC_Init 2 */

 /* USER CODE END CRC_Init 2 */

}

/**
 * @brief USART2 Initialization Function
 * @PAram None
 * @retval None
 */
static void MX_USART2_UART_Init(void)
{

 /* USER CODE BEGIN USART2_Init 0 */

 /* USER CODE END USART2_Init 0 */

 /* USER CODE BEGIN USART2_Init 1 */

 /* USER CODE END USART2_Init 1 */
 huart2.Instance = USART2;
 huart2.Init.BaudRate = 38400;
 huart2.Init.WordLength = UART_WORDLENGTH_8B;
 huart2.Init.StopBits = UART_STOPBITS_1;
 huart2.Init.Parity = UART_PARITY_NONE;
 huart2.Init.Mode = UART_MODE_TX_RX;
 huart2.Init.HwFlowCtl = UART_HWCONTROL_NONE;
 huart2.Init.OverSampling = UART_OVERSAMPLING_16;
 huart2.Init.OneBitSampling = UART_ONE_BIT_SAMPLE_DISABLE;
 huart2.AdvancedInit.AdvFeatureInit = UART_ADVFEATURE_RXOVERRUNDISABLE_INIT;
 huart2.AdvancedInit.OverrunDisable = UART_ADVFEATURE_OVERRUN_DISABLE;
 if (HAL_UART_Init(&huart2) != HAL_OK)
 {
 Error_Handler();
 }
 /* USER CODE BEGIN USART2_Init 2 */

 /* USER CODE END USART2_Init 2 */

}

/**
 * @brief GPIO Initialization Function
 * @PAram None
 * @retval None
 */
static void MX_GPIO_Init(void)
{
 GPIO_InitTypeDef GPIO_InitStruct = {0};
/* USER CODE BEGIN MX_GPIO_Init_1 */
/* USER CODE END MX_GPIO_Init_1 */

 /* GPIO Ports Clock Enable */
 __HAL_RCC_GPIOA_CLK_ENABLE();
 __HAL_RCC_GPIOB_CLK_ENABLE();

 /*Configure GPIO pin Output Level */
 HAL_GPIO_WritePin(LED3_GPIO_Port, LED3_Pin, GPIO_PIN_RESET);

 /*Configure GPIO pin : LED3_Pin */
 GPIO_InitStruct.Pin = LED3_Pin;
 GPIO_InitStruct.Mode = GPIO_MODE_OUTPUT_PP;
 GPIO_InitStruct.Pull = GPIO_NOPULL;
 GPIO_InitStruct.Speed = GPIO_SPEED_FREQ_LOW;
 HAL_GPIO_Init(LED3_GPIO_Port, &GPIO_InitStruct);

/* USER CODE BEGIN MX_GPIO_Init_2 */
/* USER CODE END MX_GPIO_Init_2 */
}

/* 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 */

 

The outputs (spaces added for readability):

inp.: 0x05 00 00 00, outp.: 0x05 00 08 dd
0x11 11 11 11, 0xdd 05 00 08
0x11 22 33 44, 0x00 31 05 00

Best answer by Tesla DeLorean

>>What am I doing wrong? Below is the code and program outputs

What's the test vector / expectation of values returned here?

	crc_out = HAL_CRC_Calculate(&hcrc, crc_input_arr, 4);
	HAL_UART_Transmit(&huart2, (uint8_t *)crc_out, 4, HAL_MAX_DELAY);

crc_out is a 32-bit variable, it needs to be a pointer and address for the HAL_UART_Transmit() function.

You've got a blind cast of the wrong type. would need to be (uint8_t *)&crc_out

 

1 reply

Tesla DeLorean
Tesla DeLoreanBest answer
Guru
May 27, 2024

>>What am I doing wrong? Below is the code and program outputs

What's the test vector / expectation of values returned here?

	crc_out = HAL_CRC_Calculate(&hcrc, crc_input_arr, 4);
	HAL_UART_Transmit(&huart2, (uint8_t *)crc_out, 4, HAL_MAX_DELAY);

crc_out is a 32-bit variable, it needs to be a pointer and address for the HAL_UART_Transmit() function.

You've got a blind cast of the wrong type. would need to be (uint8_t *)&crc_out

 

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