arduino学习笔记002.CRC校验

一、简介

　　循环冗余校验码(cyclic redundancy check)简称CRC(循环码)，是一种能力相当强的检错、纠错码，并且实现编码和检码的电路比较简单，常用于串行传送(二进制位串沿一条信号线逐位传送)的辅佐储存器与主机的数据通信和计算机网络中。循环码是指通过某种数学运算实现有效信息与校验位之间的循环校验。

　　在本章中主要实验在Arduino上的使用。

二、代码编程

2.1 典例一：8位CRC校验

代码：

#define ProCRCTable(crc_result,data) (CRC8Table[crc_result^data])

/******************************************************
 @描述:8位CRC校验
 @说明:x(8)+x(2)+x(1)+1
*******************************************************/
const unsigned char CRC8Table[256]={
    0x00, 0x07, 0x0e, 0x09, 0x1c, 0x1b, 0x12, 0x15,
    0x38, 0x3f, 0x36, 0x31, 0x24, 0x23, 0x2a, 0x2d,
    0x70, 0x77, 0x7e, 0x79, 0x6c, 0x6b, 0x62, 0x65,
    0x48, 0x4f, 0x46, 0x41, 0x54, 0x53, 0x5a, 0x5d,
    0xe0, 0xe7, 0xee, 0xe9, 0xfc, 0xfb, 0xf2, 0xf5,
    0xd8, 0xdf, 0xd6, 0xd1, 0xc4, 0xc3, 0xca, 0xcd,
    0x90, 0x97, 0x9e, 0x99, 0x8c, 0x8b, 0x82, 0x85,
    0xa8, 0xaf, 0xa6, 0xa1, 0xb4, 0xb3, 0xba, 0xbd,
    0xc7, 0xc0, 0xc9, 0xce, 0xdb, 0xdc, 0xd5, 0xd2,
    0xff, 0xf8, 0xf1, 0xf6, 0xe3, 0xe4, 0xed, 0xea,
    0xb7, 0xb0, 0xb9, 0xbe, 0xab, 0xac, 0xa5, 0xa2,
    0x8f, 0x88, 0x81, 0x86, 0x93, 0x94, 0x9d, 0x9a,
    0x27, 0x20, 0x29, 0x2e, 0x3b, 0x3c, 0x35, 0x32,
    0x1f, 0x18, 0x11, 0x16, 0x03, 0x04, 0x0d, 0x0a,
    0x57, 0x50, 0x59, 0x5e, 0x4b, 0x4c, 0x45, 0x42,
    0x6f, 0x68, 0x61, 0x66, 0x73, 0x74, 0x7d, 0x7a,
    0x89, 0x8e, 0x87, 0x80, 0x95, 0x92, 0x9b, 0x9c,
    0xb1, 0xb6, 0xbf, 0xb8, 0xad, 0xaa, 0xa3, 0xa4,
    0xf9, 0xfe, 0xf7, 0xf0, 0xe5, 0xe2, 0xeb, 0xec,
    0xc1, 0xc6, 0xcf, 0xc8, 0xdd, 0xda, 0xd3, 0xd4,
    0x69, 0x6e, 0x67, 0x60, 0x75, 0x72, 0x7b, 0x7c,
    0x51, 0x56, 0x5f, 0x58, 0x4d, 0x4a, 0x43, 0x44,
    0x19, 0x1e, 0x17, 0x10, 0x05, 0x02, 0x0b, 0x0c,
    0x21, 0x26, 0x2f, 0x28, 0x3d, 0x3a, 0x33, 0x34,
    0x4e, 0x49, 0x40, 0x47, 0x52, 0x55, 0x5c, 0x5b,
    0x76, 0x71, 0x78, 0x7f, 0x6A, 0x6d, 0x64, 0x63,
    0x3e, 0x39, 0x30, 0x37, 0x22, 0x25, 0x2c, 0x2b,
    0x06, 0x01, 0x08, 0x0f, 0x1a, 0x1d, 0x14, 0x13,
    0xae, 0xa9, 0xa0, 0xa7, 0xb2, 0xb5, 0xbc, 0xbb,
    0x96, 0x91, 0x98, 0x9f, 0x8a, 0x8D, 0x84, 0x83,
    0xde, 0xd9, 0xd0, 0xd7, 0xc2, 0xc5, 0xcc, 0xcb,
    0xe6, 0xe1, 0xe8, 0xef, 0xfa, 0xfd, 0xf4, 0xf3
};


uint8_t num_val[8]={0x01,0x02,0x03,0x04,0x05,0x06,0x07,0x08};   //被校验的数组
uint8_t crc_val=0;    //CRC校验值

void setup() 
{
  Serial.begin(115200);
}

void loop() 
{
  crc_val = CRC8_check(num_val,8);
  Serial.print("crc:0x");
  Serial.println(crc_val,HEX);
  delay(1000);
}

/****************************************************
 @函数:CRC8校验函数
 @参数:*packet:被校验的数组;
      length:数组长度
 @返回:校验结果
*****************************************************/
uint8_t CRC8_check(uint8_t *packet,uint8_t length)
{
  uint8_t i=0;
  unsigned crc_result = 0;
  for(i=0;i<length;i++)
  {
    crc_result = ProCRCTable(crc_result,packet[i]);
  }
  return crc_result;
}

 

结果：

 

 

2.2 典例二：Modbus版16位CRC校验

 代码：

uint8_t crc16_data[] = {0x01,0x04,0x04,0x43,0x6b,0x58,0x0e};
uint16_t crc_val = 0;

const uint16_t crctalbeabs[] = { 
    0x0000, 0xCC01, 0xD801, 0x1400, 0xF001, 0x3C00, 0x2800, 0xE401, 
    0xA001, 0x6C00, 0x7800, 0xB401, 0x5000, 0x9C01, 0x8801, 0x4400 
};
 
uint16_t crc16tablefast(uint8_t *ptr, uint16_t len) 
{
    uint16_t crc = 0xffff; 
    uint16_t i;
    uint8_t ch;
    for(i=0;i<len;i++) 
    {
        ch = *ptr++;
        crc = crctalbeabs[(ch ^ crc) & 15] ^ (crc >> 4);
        crc = crctalbeabs[((ch >> 4) ^ crc) & 15] ^ (crc >> 4);
    } 
    return crc;
}
void setup()
{
  Serial.begin(115200);
}
void loop()
{
    Serial.print(" Modbus CRC16 tester\n");
    crc_val = crc16tablefast(crc16_data,sizeof(crc16_data));
    Serial.print("modbus crc16tablefast calculate value:0x");
    Serial.println(crc_val,HEX);
    delay(800);
}

结果：