CRC-32 for STM32L0x

[JeroenIoT]

Hi,

I am figuring out if the libraries contain the CRC-32 functionality for the STM32L0x processor.
The processor itself contains the CRC functionality. In the end I would like to get the CRC-32 of my flashed bank.

However when testing a simple data array I get a calculated CRC which is different from other CRC-32 calculations (online, JS etc).
My guts feeling is that I am missing something or that my poly size is incorrect.

• Input (HEX): 00112233445566778899aabbccddeeff
• Expected CRC-32 (DEC): 3421780262 - see e.g. https://crccalc.com/
• Returned from code below (DEDC): 2144724613

Suggestions are welcome. My test code is below.

void calculateFlashCRC(uint32_t startAddress, uint32_t endAddress)
{
   __HAL_RCC_CRC_CLK_ENABLE();

  /* Reset the CRC generator */
  CRC->CR |= CRC_CR_RESET;

  // data array to calculate the CRC-32 
  uint8_t data[] = {0x00, 0x11, 0x22, 0x33, 0x44, 0x55, 0x66, 0x77, 0x88, 0x99, 0xAA, 0xBB, 0xCC, 0xDD, 0xEE, 0xFF};

  for (uint8_t i = 0; i < sizeof(data); i++)
  {
    CRC->DR = data[i];
  }

  /* Read the computed CRC value */
  uint32_t computedCRC = CRC->DR;

  __HAL_RCC_CRC_CLK_DISABLE();

  Serial.println("");
  Serial.print(F("calculateFlashCRC:       Received CRC:"));
  Serial.println(FT.newFW.crcChecksum);
  Serial.print(F("calculateFlashCRC:       Calculated CRC:"));
  Serial.println(computedCRC);
  Serial.flush();
}

[fpistm]

I see no HAL_CRC_Init(&hcrc);
with the

CRC_HandleTypeDef hcrc = {.Instance = CRC,
                          .InputDataFormat = CRC_INPUTDATA_FORMAT_BYTES
};

[JeroenIoT]

Thanks @fpistm - that completes the code. Nevertheless I still get a CRC of 2144724613 :-(
So there must be some flaws in my code. ... code I use now is below

void calculateFlashCRC(uint32_t startAddress, uint32_t endAddress)
{
  // Notes: 
  // Included the following header file #include <stm32l0xx_hal_crc.h>
  // In the compiler I enabled the HAL-CRC-MODULE (-DHAL_CRC_MODULE_ENABLED)

  __HAL_RCC_CRC_CLK_ENABLE();

  CRC_HandleTypeDef hcrc;

  hcrc.Instance = CRC;
  hcrc.InputDataFormat = CRC_INPUTDATA_FORMAT_BYTES; // CRC_INPUTDATA_FORMAT_WORDS;    //CRC_INPUTDATA_FORMAT_BYTES;
  hcrc.Init.DefaultPolynomialUse = DEFAULT_POLYNOMIAL_ENABLE;
  hcrc.Init.DefaultInitValueUse = DEFAULT_INIT_VALUE_ENABLE;
  //hcrc.Init.GeneratingPolynomial = DEFAULT_CRC32_POLY; // No need to specify it if DefaultPolynomialUse is set to DEFAULT_POLYNOMIAL_ENABLE.   */
  hcrc.Init.CRCLength = CRC_POLYLENGTH_32B;
  //hcrc.Init.InitValue = ; // No need to specify it if DefaultInitValueUse is set to DEFAULT_INIT_VALUE_ENABLE.   */           
  hcrc.Init.InputDataInversionMode = CRC_INPUTDATA_INVERSION_NONE;
  hcrc.Init.OutputDataInversionMode = CRC_OUTPUTDATA_INVERSION_DISABLE;    // CRC_OUTPUTDATA_INVERSION_DISABLE   / CRC_OUTPUTDATA_INVERSION_ENABLE
  
  if (HAL_CRC_Init(&hcrc) != HAL_OK)
  {
    /* Initialization Error */
    Error_Handler();
  }
  
  // CRC input
  uint8_t data[] = {0x00, 0x11, 0x22, 0x33, 0x44, 0x55, 0x66, 0x77, 0x88, 0x99, 0xAA, 0xBB, 0xCC, 0xDD, 0xEE, 0xFF};

  Serial.print(F("calculateFlashCRC:       data: "));
  for (uint8_t i = 0; i < sizeof(data); i++)
  {
    ((CRC_TypeDef*) hcrc.Instance)->DR = data[i];
    Serial.print(data[i]);
    Serial.print("-");
  }

    /* Read the computed CRC value */
  uint32_t computedCRC = ((CRC_TypeDef*) hcrc.Instance)->DR;

  __HAL_RCC_CRC_CLK_DISABLE();

  #ifdef DEBUG
    Serial.println("");
    Serial.print(F("calculateFlashCRC:       Calculated CRC:"));
    Serial.println(computedCRC);
    Serial.flush();
  #endif
}

[fpistm]

I never used CRC. You should check CubeL0 examples maybe you will find what is missing.

[JeroenIoT]

Thanks for the feedback. Will check cube and once it is working I will drop my code here

[JeroenIoT]

Seems ST CRC algorithm is different from the commonly used CRCs

See https://github.com/dimmykar/stm32-crc32-calculator

[fpistm]

OK. I'm not aware of this.

[JeroenIoT]

Have not figured out how ST's CRC differs from the "normal" CRC.
For me this topic is closed