STM32F4串口通信自定义数据包（CRC32校验）_串口发送自定义数据

内容简介

1. 时间戳一般为32位，单次串口通信位8位，因此可将一个32位分解为四个8位，组成数据包形式发送

   /*           自定义数据包
   *            +----------+--------+-----------+--------------------+----------+
   *            | preamble | 000000 |  length   |    data message    |  parity  |
   *            +----------+--------+-----------+--------------------+----------+
   *            |<-- 8 --->|<- 16 ->|<--- 8 --->|<------- 96 ------->|<-- 32 -->| */
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2. 为保证数据完整无误，采用crc32校验
3. 接收设备进行软件crc32计算校验

一、硬件CRC32

参考博客

__asm uint32_t Revbit (uint32_t data)	
{
	RBIT	R0, R0
	BX		LR
}

__asm uint32_t Revswap(uint32_t data)
{
	REV	R0, R0
	BX		LR
}

void crc32_init(void)
{
	__HAL_RCC_CRC_CLK_ENABLE();
	CRC->CR = CRC_CR_RESET;	
}

uint32_t crc32_cal(uint32_t data)
{
	CRC->DR = Revbit(Revswap(data));
	return (Revbit(CRC->DR)^0xFFFFFFFF);
}

uint32_t crc32_cal_buffer(uint32_t *buffer, uint32_t length)
{
	uint32_t i = 0;
	CRC->CR = CRC_CR_RESET;
	for(i = 0; i<length-1; i++) {
		crc32_cal(buffer[i]);
	}
	return crc32_cal(buffer[i]);
}
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二、软件CRC32（查表）

static const uint32_t tbl_CRC32[] =
{
    0x00000000, 0x77073096, 0xee0e612c, 0x990951ba, 0x076dc419, 0x706af48f,
    0xe963a535, 0x9e6495a3, 0x0edb8832, 0x79dcb8a4, 0xe0d5e91e, 0x97d2d988,
    0x09b64c2b, 0x7eb17cbd, 0xe7b82d07, 0x90bf1d91, 0x1db71064, 0x6ab020f2,
    0xf3b97148, 0x84be41de, 0x1adad47d, 0x6ddde4eb, 0xf4d4b551, 0x83d385c7,
    0x136c9856, 0x646ba8c0, 0xfd62f97a, 0x8a65c9ec, 0x14015c4f, 0x63066cd9,
    0xfa0f3d63, 0x8d080df5, 0x3b6e20c8, 0x4c69105e, 0xd56041e4, 0xa2677172,
    0x3c03e4d1, 0x4b04d447, 0xd20d85fd, 0xa50ab56b, 0x35b5a8fa, 0x42b2986c,
    0xdbbbc9d6, 0xacbcf940, 0x32d86ce3, 0x45df5c75, 0xdcd60dcf, 0xabd13d59,
    0x26d930ac, 0x51de003a, 0xc8d75180, 0xbfd06116, 0x21b4f4b5, 0x56b3c423,
    0xcfba9599, 0xb8bda50f, 0x2802b89e, 0x5f058808, 0xc60cd9b2, 0xb10be924,
    0x2f6f7c87, 0x58684c11, 0xc1611dab, 0xb6662d3d, 0x76dc4190, 0x01db7106,
    0x98d220bc, 0xefd5102a, 0x71b18589, 0x06b6b51f, 0x9fbfe4a5, 0xe8b8d433,
    0x7807c9a2, 0x0f00f934, 0x9609a88e, 0xe10e9818, 0x7f6a0dbb, 0x086d3d2d,
    0x91646c97, 0xe6635c01, 0x6b6b51f4, 0x1c6c6162, 0x856530d8, 0xf262004e,
    0x6c0695ed, 0x1b01a57b, 0x8208f4c1, 0xf50fc457, 0x65b0d9c6, 0x12b7e950,
    0x8bbeb8ea, 0xfcb9887c, 0x62dd1ddf, 0x15da2d49, 0x8cd37cf3, 0xfbd44c65,
    0x4db26158, 0x3ab551ce, 0xa3bc0074, 0xd4bb30e2, 0x4adfa541, 0x3dd895d7,
    0xa4d1c46d, 0xd3d6f4fb, 0x4369e96a, 0x346ed9fc, 0xad678846, 0xda60b8d0,
    0x44042d73, 0x33031de5, 0xaa0a4c5f, 0xdd0d7cc9, 0x5005713c, 0x270241aa,
    0xbe0b1010, 0xc90c2086, 0x5768b525, 0x206f85b3, 0xb966d409, 0xce61e49f,
    0x5edef90e, 0x29d9c998, 0xb0d09822, 0xc7d7a8b4, 0x59b33d17, 0x2eb40d81,
    0xb7bd5c3b, 0xc0ba6cad, 0xedb88320, 0x9abfb3b6, 0x03b6e20c, 0x74b1d29a,
    0xead54739, 0x9dd277af, 0x04db2615, 0x73dc1683, 0xe3630b12, 0x94643b84,
    0x0d6d6a3e, 0x7a6a5aa8, 0xe40ecf0b, 0x9309ff9d, 0x0a00ae27, 0x7d079eb1,
    0xf00f9344, 0x8708a3d2, 0x1e01f268, 0x6906c2fe, 0xf762575d, 0x806567cb,
    0x196c3671, 0x6e6b06e7, 0xfed41b76, 0x89d32be0, 0x10da7a5a, 0x67dd4acc,
    0xf9b9df6f, 0x8ebeeff9, 0x17b7be43, 0x60b08ed5, 0xd6d6a3e8, 0xa1d1937e,
    0x38d8c2c4, 0x4fdff252, 0xd1bb67f1, 0xa6bc5767, 0x3fb506dd, 0x48b2364b,
    0xd80d2bda, 0xaf0a1b4c, 0x36034af6, 0x41047a60, 0xdf60efc3, 0xa867df55,
    0x316e8eef, 0x4669be79, 0xcb61b38c, 0xbc66831a, 0x256fd2a0, 0x5268e236,
    0xcc0c7795, 0xbb0b4703, 0x220216b9, 0x5505262f, 0xc5ba3bbe, 0xb2bd0b28,
    0x2bb45a92, 0x5cb36a04, 0xc2d7ffa7, 0xb5d0cf31, 0x2cd99e8b, 0x5bdeae1d,
    0x9b64c2b0, 0xec63f226, 0x756aa39c, 0x026d930a, 0x9c0906a9, 0xeb0e363f,
    0x72076785, 0x05005713, 0x95bf4a82, 0xe2b87a14, 0x7bb12bae, 0x0cb61b38,
    0x92d28e9b, 0xe5d5be0d, 0x7cdcefb7, 0x0bdbdf21, 0x86d3d2d4, 0xf1d4e242,
    0x68ddb3f8, 0x1fda836e, 0x81be16cd, 0xf6b9265b, 0x6fb077e1, 0x18b74777,
    0x88085ae6, 0xff0f6a70, 0x66063bca, 0x11010b5c, 0x8f659eff, 0xf862ae69,
    0x616bffd3, 0x166ccf45, 0xa00ae278, 0xd70dd2ee, 0x4e048354, 0x3903b3c2,
    0xa7672661, 0xd06016f7, 0x4969474d, 0x3e6e77db, 0xaed16a4a, 0xd9d65adc,
    0x40df0b66, 0x37d83bf0, 0xa9bcae53, 0xdebb9ec5, 0x47b2cf7f, 0x30b5ffe9,
    0xbdbdf21c, 0xcabac28a, 0x53b39330, 0x24b4a3a6, 0xbad03605, 0xcdd70693,
    0x54de5729, 0x23d967bf, 0xb3667a2e, 0xc4614ab8, 0x5d681b02, 0x2a6f2b94,
    0xb40bbe37, 0xc30c8ea1, 0x5a05df1b, 0x2d02ef8d
};

uint32_t crc32(uint8_t *input, uint32_t len)
{
	uint32_t crc = 0xFFFFFFFF, i;

	for (i = 0; i<len; i++) {
		crc = tbl_CRC32[(crc ^ input[i]) & 0xff ] ^ (crc >> 8);
	}
	return crc ^ 0xFFFFFFFF;
}
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三、测试

1.单片机例程

#include "./SYSTEM/sys/sys.h"
#include "./SYSTEM/usart/usart.h"
#include "./SYSTEM/delay/delay.h"
#include "./BSP/LED/led.h"
#include "./BSP/KEY/key.h"
#include "./BSP/CRC/crc32.h"


int main(void)
{
	uint32_t data[5];
	uint8_t buffer[20];
//	uint8_t *buffer;

    HAL_Init();                                 /* 初始化HAL */
    sys_stm32_clock_init(336, 8, 2, 7);         /* 初始化时钟,168Mhz */
    delay_init(168);                            /* 初始化延迟 */
    usart_init(115200);                         /* 初始化串口 */
    led_init();                                 /* 初始化LED */
    key_init();                                 /* 初始化按键 */
	crc32_init();								/* 初始化CRC32 */
	
/*           自定义数据包
*            +----------+--------+-----------+--------------------+----------+
*            | preamble | 000000 |  length   |    data message    |  parity  |
*            +----------+--------+-----------+--------------------+----------+
*            |<-- 8 --->|<- 16 ->|<--- 8 --->|<------- 96 ------->|<-- 32 -->| */
	data[0] = (data[0] & 0U) | 0xCCU << 24 | 0xCU;
	data[1] = 100;
	data[2] = 1684750330;
	data[3] = 111111111;
	data[4] = crc32_cal_buffer(data, 4);
//	buffer = (uint8_t *)data;
	
    while(1)
    {
	#if 1
		for (uint8_t i=0, ind=0; i<5; i++) {
			for (uint8_t j=0, pos=24; j<4; j++, ind++, pos-=8) {
				buffer[ind] = data[i] >> pos;
				usart_send_byte(&g_uart1_handle, buffer[ind]);
			}
		}
	#else
		// 小端模式 data[0]中的帧头cc是buffer[3]
//		for (uint8_t i=0; i<20; i++) {
//			usart_send_byte(&g_uart1_handle, buffer[i]);
//		}
	#endif
		delay_ms(5000);
    }
}

}

// 串口HEX输出， 软硬件计算的CRC32均为D8 BA E4 74
CC 00 00 0C 00 00 00 64 64 6B 3F FA 06 9F 6B C7 D8 BA E4 74
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2.linux串口通信解码测试

这里贴出解读数据包的主要代码，参考开源软件RTKLIB https://github.com/tomojitakasu/RTKLIB/blob/master/src/rtcm.c

typedef struct
{
    uint32_t Sec;
    uint32_t Nsec;
    uint32_t FrameNum;
}Time_Frame_Header;

typedef struct
{
    Time_Frame_Header data;
    uint8_t buff[200];          /* message buffer */
    uint32_t nbyte;             /* number of bytes in message buffer */
    uint32_t len;               /* message length (bytes) */
}Serial_Data_Bag;

static int8_t input_message(Serial_Data_Bag *bag, uint8_t data)
{
    /* synchronize frame */
    if (bag->nbyte == 0) {
        if (data != CCPREAMB) return 0;
        bag->buff[bag->nbyte++] = data;
        return 0;
    }
    bag->buff[bag->nbyte++] = data;
    
    if (bag->nbyte == 4) {
        bag->len = getbitu(bag->buff, 24, 8) + 4; /* 没有校验位的数据包长度 */
    }
    if (bag->nbyte < 4 || bag->nbyte < bag->len+4) return 0;
    bag->nbyte = 0;    // 到这里接收到理论长度的数据包！！重置nbyte

    /* 检验数据包 */
    if (crc32(bag->buff, bag->len) != getbitu(bag->buff, bag->len*8, 32)) {
        ROS_ERROR("serial_data_bag parity error: len=%d byte\n", bag->len);
        return 0;
    }
    /* 消息完整通过检验 开始解读消息 */
    uint32_t ind = 32;
    bag->data.FrameNum = getbitu(bag->buff, ind, 32); ind += 32;
    bag->data.Sec      = getbitu(bag->buff, ind, 32); ind += 32;
    bag->data.Nsec     = getbitu(bag->buff, ind, 32);
    
    return 1;
}
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