stm32f103re CRC ?

[kshin.111]

hi 

i used of CRC in stm32CubeMX and for check true worked CRC used of two online CRC calculator site:

https://www.sunshine2k.de/coding/javascript/crc/crc_js.html

&

https://crccalc.com/?crc=123456789&method=&datatype=0&outtype=0

i think stm32cubeIDE internal CRC use of standard CRC32_MPEG2:

Polynomial = 0x4C11DB7

Initial value = 0xFFFFFFFF

Final XoR Value = 0x0

Input reflected = disable

Result reflected = disable

Am I correct and have I written the CRC parameter values ​​for stm32f103 exactly right?

...........

but CRC result for stm32CubeIDE different with online CRC calculator site?

example:

stm32 CRC for 0x00 = 0xc704dd7b

online CRC calculator site for 0x00 = 0x4E08BFB4

stm32 CRC for 0x01 = 0xc3c5c0cc

online CRC calculator site for 0x01 = 0x4AC9A203

stm32 CRC for 0x02 = 0xce86e615

online CRC calculator site for 0x02 = 0x478A84DA

stm32 CRC for 0xFF = 0x76f39dcf

online CRC calculator site for 0xFF = 0xFFFFFF00

............ my Code:

#include "main.h"
void SystemClock_Config(void);
int main(void)
{
	extern CRC_HandleTypeDef hcrc;
	//CRC
	uint32_t buff[2];
	uint32_t result = 0xffffffff;
	uint32_t i = 0;
        //
	HAL_Init();
	SystemClock_Config();
	MX_GPIO_Init();
	MX_USART1_UART_Init();
	MX_I2C1_Init();
	MX_SPI1_Init();
	MX_CRC_Init();
	while (1)
	{
		i = 0;
		while(i < 256)
		{
			buff[0] = i;
			result = HAL_CRC_Calculate(&hcrc, &buff[0], 1);
			i++;
		}
	}
}

-------------------------

please help me

[PGump.1]

Hi,

Are you using the polynomial reversed, or the reciprocal?

Kind regards
Pedro

[kshin.111]

stm32cubeIDE CRC for STM32F103RE is constant value and can not change any CRC parameter.

and i used for one Byte value.

0

1

2

0xFF

I don't make any changes to the data.

I have read various CRC documents from st company and nowhere I have seen the value of CRC parameters used for STM32F103 so I don't know if it uses Reverse or Reciprocal or not.

[PGump.1]

Hi,

The CRC unit needs to be Reset between each set of calculations. If HAL doesn't have a reset function, then try something like -

    CRC->CR |= CRC_CR_RESET;

before i = 0;

I hope this helps.

Kind regards
Pedro

[waclawek.jan · Accepted solution]

The CRC unit in 'F1 calculates CRC only from 32-bit words, so for example for your 0x01 input it uses 0x00000001 (big endian, so 0x00 0x00 0x00 0x01):

JW

[kshin.111]

HAL automatic reset for function "HAL_CRC_Calculate()"

[kshin.111]

thanks thanks thanks