初出茅庐的小李第61篇博客之C语言实现Modbus_CRC16值计算
Modbus_CRC16计算方法
我们经常会在一些场合用到CRC值，简单的时候我们可以使用CRC校验工具计算，但是如果我们传输的的数据是变化的话这时候再用CRC在线计算工具就不行了。
c语言方式实现记录
我也不懂原理 原理和实际计算的时候还是有点差别的直接在工程中应用，我就关心怎么实现，所以我就记录一下如何计算这个CRC值
- 直接计算方法
/*
*Modbus_CRC校验值计算函数
*/
uint16_t Modbus_CRC16(uint8_t *pBfr, uint32_t size)
{
uint16_t CRC_16 = 0xFFFF; /*define CRC ((CRC_TypeDef *) CRC_BASE))不能命名为CRC(库函数冲突*/
for (uint32_t i = 0; i < size; i++)
{
CRC_16 ^= pBfr[i];
for (uint8_t j = 0; j < 8; j++)
{
if (CRC_16 & 0x0001)
{
CRC_16 >>= 1;
CRC_16 ^= 0xA001;
}
else
{
CRC_16 >>= 1;
}
}
}
return CRC_16;
}
- 查表计算法
#include "crc.h"
static const UCHAR aucCRCHi[] =
{
0x00, 0xC1, 0x81, 0x40, 0x01, 0xC0, 0x80, 0x41, 0x01, 0xC0, 0x80, 0x41,
0x00, 0xC1, 0x81, 0x40, 0x01, 0xC0, 0x80, 0x41, 0x00, 0xC1, 0x81, 0x40,
0x00, 0xC1, 0x81, 0x40, 0x01, 0xC0, 0x80, 0x41, 0x01, 0xC0, 0x80, 0x41,
0x00, 0xC1, 0x81, 0x40, 0x00, 0xC1, 0x81, 0x40, 0x01, 0xC0, 0x80, 0x41,
0x00, 0xC1, 0x81, 0x40, 0x01, 0xC0, 0x80, 0x41, 0x01, 0xC0, 0x80, 0x41,
0x00, 0xC1, 0x81, 0x40, 0x01, 0xC0, 0x80, 0x41, 0x00, 0xC1, 0x81, 0x40,
0x00, 0xC1, 0x81, 0x40, 0x01, 0xC0, 0x80, 0x41, 0x00, 0xC1, 0x81, 0x40,
0x01, 0xC0, 0x80, 0x41, 0x01, 0xC0, 0x80, 0x41, 0x00, 0xC1, 0x81, 0x40,
0x00, 0xC1, 0x81, 0x40, 0x01, 0xC0, 0x80, 0x41, 0x01, 0xC0, 0x80, 0x41,
0x00, 0xC1, 0x81, 0x40, 0x01, 0xC0, 0x80, 0x41, 0x00, 0xC1, 0x81, 0x40,
0x00, 0xC1, 0x81, 0x40, 0x01, 0xC0, 0x80, 0x41, 0x01, 0xC0, 0x80, 0x41,
0x00, 0xC1, 0x81, 0x40, 0x00, 0xC1, 0x81, 0x40, 0x01, 0xC0, 0x80, 0x41,
0x00, 0xC1, 0x81, 0x40, 0x01, 0xC0, 0x80, 0x41, 0x01, 0xC0, 0x80, 0x41,
0x00, 0xC1, 0x81, 0x40, 0x00, 0xC1, 0x81, 0x40, 0x01, 0xC0, 0x80, 0x41,
0x01, 0xC0, 0x80, 0x41, 0x00, 0xC1, 0x81, 0x40, 0x01, 0xC0, 0x80, 0x41,
0x00, 0xC1, 0x81, 0x40, 0x00, 0xC1, 0x81, 0x40, 0x01, 0xC0, 0x80, 0x41,
0x00, 0xC1, 0x81, 0x40, 0x01, 0xC0, 0x80, 0x41, 0x01, 0xC0, 0x80, 0x41,
0x00, 0xC1, 0x81, 0x40, 0x01, 0xC0, 0x80, 0x41, 0x00, 0xC1, 0x81, 0x40,
0x00, 0xC1, 0x81, 0x40, 0x01, 0xC0, 0x80, 0x41, 0x01, 0xC0, 0x80, 0x41,
0x00, 0xC1, 0x81, 0x40, 0x00, 0xC1, 0x81, 0x40, 0x01, 0xC0, 0x80, 0x41,
0x00, 0xC1, 0x81, 0x40, 0x01, 0xC0, 0x80, 0x41, 0x01, 0xC0, 0x80, 0x41,
0x00, 0xC1, 0x81, 0x40
};
static const UCHAR aucCRCLo[] =
{
0x00, 0xC0, 0xC1, 0x01, 0xC3, 0x03, 0x02, 0xC2, 0xC6, 0x06, 0x07, 0xC7,
0x05, 0xC5, 0xC4, 0x04, 0xCC, 0x0C, 0x0D, 0xCD, 0x0F, 0xCF, 0xCE, 0x0E,
0x0A, 0xCA, 0xCB, 0x0B, 0xC9, 0x09, 0x08, 0xC8, 0xD8, 0x18, 0x19, 0xD9,
0x1B, 0xDB, 0xDA, 0x1A, 0x1E, 0xDE, 0xDF, 0x1F, 0xDD, 0x1D, 0x1C, 0xDC,
0x14, 0xD4, 0xD5, 0x15, 0xD7, 0x17, 0x16, 0xD6, 0xD2, 0x12, 0x13, 0xD3,
0x11, 0xD1, 0xD0, 0x10, 0xF0, 0x30, 0x31, 0xF1, 0x33, 0xF3, 0xF2, 0x32,
0x36, 0xF6, 0xF7, 0x37, 0xF5, 0x35, 0x34, 0xF4, 0x3C, 0xFC, 0xFD, 0x3D,
0xFF, 0x3F, 0x3E, 0xFE, 0xFA, 0x3A, 0x3B, 0xFB, 0x39, 0xF9, 0xF8, 0x38,
0x28, 0xE8, 0xE9, 0x29, 0xEB, 0x2B, 0x2A, 0xEA, 0xEE, 0x2E, 0x2F, 0xEF,
0x2D, 0xED, 0xEC, 0x2C, 0xE4, 0x24, 0x25, 0xE5, 0x27, 0xE7, 0xE6, 0x26,
0x22, 0xE2, 0xE3, 0x23, 0xE1, 0x21, 0x20, 0xE0, 0xA0, 0x60, 0x61, 0xA1,
0x63, 0xA3, 0xA2, 0x62, 0x66, 0xA6, 0xA7, 0x67, 0xA5, 0x65, 0x64, 0xA4,
0x6C, 0xAC, 0xAD, 0x6D, 0xAF, 0x6F, 0x6E, 0xAE, 0xAA, 0x6A, 0x6B, 0xAB,
0x69, 0xA9, 0xA8, 0x68, 0x78, 0xB8, 0xB9, 0x79, 0xBB, 0x7B, 0x7A, 0xBA,
0xBE, 0x7E, 0x7F, 0xBF, 0x7D, 0xBD, 0xBC, 0x7C, 0xB4, 0x74, 0x75, 0xB5,
0x77, 0xB7, 0xB6, 0x76, 0x72, 0xB2, 0xB3, 0x73, 0xB1, 0x71, 0x70, 0xB0,
0x50, 0x90, 0x91, 0x51, 0x93, 0x53, 0x52, 0x92, 0x96, 0x56, 0x57, 0x97,
0x55, 0x95, 0x94, 0x54, 0x9C, 0x5C, 0x5D, 0x9D, 0x5F, 0x9F, 0x9E, 0x5E,
0x5A, 0x9A, 0x9B, 0x5B, 0x99, 0x59, 0x58, 0x98, 0x88, 0x48, 0x49, 0x89,
0x4B, 0x8B, 0x8A, 0x4A, 0x4E, 0x8E, 0x8F, 0x4F, 0x8D, 0x4D, 0x4C, 0x8C,
0x44, 0x84, 0x85, 0x45, 0x87, 0x47, 0x46, 0x86, 0x82, 0x42, 0x43, 0x83,
0x41, 0x81, 0x80, 0x40
};
/*
*Modbus_CRC校验值计算函数
*/
uint16_t Modbus_CRC16(uint8_t *pBfr, uint32_t size)
{
uint16_t CRC_16 = 0xFFFF; /*define CRC ((CRC_TypeDef *) CRC_BASE))不能命名为CRC(库函数冲突*/
for (uint32_t i = 0; i < size; i++)
{
CRC_16 ^= pBfr[i];
for (uint8_t j = 0; j < 8; j++)
{
if (CRC_16 & 0x0001)
{
CRC_16 >>= 1;
CRC_16 ^= 0xA001;
}
else
{
CRC_16 >>= 1;
}
}
}
return CRC_16;
}
USHORT MBCRC16( UCHAR * pucFrame, USHORT usLen )
{
UCHAR ucCRCHi = 0xFF;
UCHAR ucCRCLo = 0xFF;
int iIndex;
while( usLen-- )
{
iIndex = ucCRCLo ^ *( pucFrame++ );
ucCRCLo = ( UCHAR )( ucCRCHi ^ aucCRCHi[iIndex] );
ucCRCHi = aucCRCLo[iIndex];
}
return ( USHORT )( ucCRCHi << 8 | ucCRCLo );
}
测试程序
/*
*Modbus通信数据组包和计算
*/
void my_Test4(void)
{
uint16_t CRC_Val = 0;
uint8_t pBff[10] = {0};
pBff[0]=0xAB;
memset(&pBff[1], 0xFF, 7);
CRC_Val = Modbus_CRC16(pBff,8);
pBff[8]= ( uint8_t )( (CRC_Val & 0x00FF) ); //截取低八位高八位清零
pBff[9]= ( uint8_t )( (CRC_Val & 0xff00) >> 8 ); //截取高八位放到低八位
//printf("%s",pBff);/*十六进显示打印*/
printf("\r\n第一种方法\r\n");
for(uint8_t i = 0;i<10;i++)
{
/*字符显示打印*/
printf("0x%02X ",pBff[i]);
}
memset(&pBff[1], 0xBB, 7);
CRC_Val = MBCRC16(pBff,8);
printf("\r\n");
pBff[8]= ( uint8_t )( (CRC_Val & 0x00FF) ); //截取低八位高八位清零
pBff[9]= ( uint8_t )( (CRC_Val & 0xff00) >> 8 ); //截取高八位放到低八位
printf("第二种方法\r\n");
for(uint8_t i = 0;i<10;i++)
{
/*字符显示打印*/
printf("0x%02X ",pBff[i]);
}
}
测试效果
