RT-Thread-N32G45x 硬件CRC32RT-Thread问答社区

N32G45x 硬件CRC32

发布于 2022-04-01 11:46:55 浏览：969 订阅该版

**N32G45x 硬件CRC32**

需要大家一起努力，努力去测试，找出问题，帮助产家积累经验。

这里所述的，是在官方文档中没有写的，在国民技术工程师王一民同志的帮助下，完成测试，俺只是搬运工。干货来了，这个硬件CRC32得出的结果是CRC-32/MPEG-2这个模型。直接上图参考

//04C11DB7
//MSB
//初值 FFFFFFFF
//异或 00000000

![image.png](https://oss-club.rt-thread.org/uploads/20220401/ec7a64368e2762918ba475cb1f066ed2.png)

这个网站，可以计算CRC http://www.metools.info/code/c15.html

附上王工给的测试代码
```c
/**
 * @file main.c
 * @author Nations
 * @version v1.0.0
 *
 * @copyright Copyright (c) 2019, Nations Technologies Inc. All rights reserved.
 */
#include "n32g45x.h"
#include <stdio.h>
#include <string.h>

#define USED_BIG_ENDIAN
#define POLY 0x4C11DB7

void usart1_init(uint32_t baudval);

/** @addtogroup N32WB452_StdPeriph_Examples
 * @{
 */

/** @addtogroup CRC_Calculation
 * @{
 */

static const uint8_t Buffer_8[11] = {1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11};
uint32_t CRCValue;

uint32_t revbit(uint32_t uData)
{
    uint32_t uRevData = 0, uIndex = 0;
    uRevData |= ((uData >> uIndex) & 0x01);
	
    for(uIndex = 1; uIndex < 32; uIndex++)
    {
        uRevData <<= 1;
        uRevData |= ((uData >> uIndex) & 0x01);
    }
    return uRevData;
}

uint32_t swap_endian(uint32_t data)
{
    int temp = 0;

temp = ((data & 0x000000FF) << 24) |
	
           ((data & 0x0000FF00) << 8)  |
	
           ((data & 0x00FF0000) >> 8)  |
	
           ((data & 0xFF000000) >> 24);

return temp;
}

uint32_t crc32_bytes(uint8_t *pData, uint32_t uLen)
{
    uint32_t uIndex = 0, crc_value = 0;
    uint32_t i;
    
    uIndex = uLen >> 2;
    
    while (uIndex--)
    {
#ifdef USED_BIG_ENDIAN
	    memcpy((uint8_t *)&crc_value, pData, 4);
		crc_value = swap_endian(crc_value);
#else
		memcpy((uint8_t *)&crc_value, pData, 4);
#endif

pData += 4;
		CRC->CRC32DAT = crc_value;
    }
    crc_value = CRC->CRC32DAT;
    
    uIndex = uLen & 0x03;
		
	if(uIndex == 0)
		return crc_value;

while (uIndex--)
    {
        crc_value ^= (*pData++) << 24;
    
        for (i = 0; i < 8; i++)
        {
            if (crc_value & 0x80000000)
                crc_value = (crc_value << 1) ^ POLY;
            else
                crc_value <<= 1;
        }
    }

return crc_value;
}

/**
 * @brief  Main program.
 */
int main(void)
{
    /*!< At this stage the microcontroller clock setting is already configured,
         this is done through SystemInit() function which is called from startup
         file (startup_n32wb452.s) before to branch to application main.
         To reconfigure the default setting of SystemInit() function, refer to
         system_n32wb452.c file
       */
	
    usart1_init(115200UL);
    printf("\n\rUSART1 function ok!\n\r");
	
	  
    /* Enable CRC clock */
    RCC_EnableAHBPeriphClk(RCC_AHB_PERIPH_CRC, ENABLE);
	CRC32_ResetCrc();

/* Compute the 32bit CRC of "DataBuffer" */
    CRCValue = crc32_bytes((uint8_t*)Buffer_8, 11);
	//CRCValue = CRC32_CalcCrc(0x01020304);
	//CRCValue = CRC32_CalcCrc(0x05060708);

printf("The crc32 vaule is 0x%x", CRCValue);

while (1)
    {
    }
}

void usart1_init(uint32_t baudval)
{
    GPIO_InitType GPIO_InitStructure;
    USART_InitType USART_InitStructure;

/* Enable GPIO clock */
    RCC_EnableAPB2PeriphClk(RCC_APB2_PERIPH_GPIOA | RCC_APB2_PERIPH_AFIO, ENABLE);
    /* Enable USART1 Clock */
    RCC_EnableAPB2PeriphClk(RCC_APB2_PERIPH_USART1, ENABLE);

/* Configure USART1 Tx as alternate function push-pull */
    GPIO_InitStructure.Pin        = GPIO_PIN_9;
    GPIO_InitStructure.GPIO_Speed = GPIO_Speed_50MHz;
    GPIO_InitStructure.GPIO_Mode  = GPIO_Mode_AF_PP;
    GPIO_InitPeripheral(GPIOA, &GPIO_InitStructure);

/* Configure USART1 Rx as input floating */
    GPIO_InitStructure.Pin       = GPIO_PIN_10;
    GPIO_InitStructure.GPIO_Mode = GPIO_Mode_IN_FLOATING;
    GPIO_InitPeripheral(GPIOA, &GPIO_InitStructure);

/* USART1 configuration ------------------------------------------------------*/
    USART_InitStructure.BaudRate            = baudval;
    USART_InitStructure.WordLength          = USART_WL_8B;
    USART_InitStructure.StopBits            = USART_STPB_1;
    USART_InitStructure.Parity              = USART_PE_NO;
    USART_InitStructure.HardwareFlowControl = USART_HFCTRL_NONE;
    USART_InitStructure.Mode                = USART_MODE_RX | USART_MODE_TX;

/* Configure USART1 */
    USART_Init(USART1, &USART_InitStructure);
    /* Enable the USART1 */
    USART_Enable(USART1, ENABLE);
}

/* retarget the C library printf function to the USART */
int fputc(int ch, FILE* f)
{
    USART_SendData(USART1, (uint8_t)ch);
    while (USART_GetFlagStatus(USART1, USART_FLAG_TXDE) == RESET)
        ;

return (ch);
}

#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
 */
void assert_failed(const uint8_t* expr, const uint8_t* file, uint32_t line)
{
    /* 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) */

/* Infinite loop */
    while (1)
    {
    }
}
#endif
```
好了，下午再对这个进行RTT下驱动的改造，同样是给它上个锁。吃饭去。