Concox跟踪器的16位CRC-ITU计算

16bit CRC-ITU calculation for Concox tracker

我正在为通过 TCP 从 Concox TR06 GPS 跟踪器接收数据的服务器程序创建 C# 代码:

http://www.iconcox.com/uploads/soft/140920/1-140920023130.pdf

首次启动时,跟踪器会发送一条登录消息,在发送任何位置数据之前需要确认该消息。我的第一个问题是,根据文档,确认消息长 18 个字节,但他们提供的示例只有 10 个字节长:

P.s。在上面的 table 中,我很确定 "bits" 列应该标记为 "bytes" 而不是...

现在,我的主要问题是计算错误检查。根据文档:

校验码采用CRC-ITU校验方式生成。协议结构中数据的校验码,从Packet Length到Information Serial Number(包括"Packet Length"和"Information Serial Number")都是CRC-ITU的值。

好的,所以在上面的例子中,我需要在0x05 0x01 0x00 0x01上计算CRC

现在,我猜它是 16 位 CRC,根据上图,CRC 长度为 2 个字节。我已经实现了两种不同的 CRC 实现,我在 http://www.sanity-free.org/134/standard_crc_16_in_csharp.html and http://www.sanity-free.org/133/crc_16_ccitt_in_csharp.html but neither give me the answer that, according to the diagram above I am supposed to be getting - 0xD9 0xDC. I've even used this site - https://www.lammertbies.nl/comm/info/crc-calculation.html 网上找到了 - 手动输入 4 个字节,但没有任何东西给我根据上图应该得到的结果......

我有什么地方可能出错的想法吗?任何 pointers/hints 将不胜感激。谢谢

ITU CRC-16 也称为 X-25 CRC。你可以找到它的规格here,即:

width=16 poly=0x1021 init=0xffff refin=true refout=true xorout=0xffff check=0x906e name="X-25"

我的 crcany code 将采用该规范并生成 C 代码来计算 CRC。

这是由此生成的按位(慢)代码:

#include <stddef.h>

unsigned crc16x_25_bit(unsigned crc, void const *data, size_t len) {
    if (data == NULL)
        return 0;
    crc = ~crc;
    crc &= 0xffff;
    while (len--) {
        crc ^= *(unsigned char const *)data++;
        for (unsigned k = 0; k < 8; k++)
            crc = crc & 1 ? (crc >> 1) ^ 0x8408 : crc >> 1;
    }
    crc ^= 0xffff;
    return crc;
}

我在 nodejs (javascript) 中实现了相同的逻辑。我希望这对某人有所帮助。

const crc16itu = hexString => {

if (!hexString) return 0x00;
const table = [
    0x0000, 0x1189, 0x2312, 0x329B, 0x4624, 0x57AD, 0x6536, 0x74BF,
    0x8C48, 0x9DC1, 0xAF5A, 0xBED3, 0xCA6C, 0xDBE5, 0xE97E, 0xF8F7,
    0x1081, 0x0108, 0x3393, 0x221A, 0x56A5, 0x472C, 0x75B7, 0x643E,
    0x9CC9, 0x8D40, 0xBFDB, 0xAE52, 0xDAED, 0xCB64, 0xF9FF, 0xE876,
    0x2102, 0x308B, 0x0210, 0x1399, 0x6726, 0x76AF, 0x4434, 0x55BD,
    0xAD4A, 0xBCC3, 0x8E58, 0x9FD1, 0xEB6E, 0xFAE7, 0xC87C, 0xD9F5,
    0x3183, 0x200A, 0x1291, 0x0318, 0x77A7, 0x662E, 0x54B5, 0x453C,
    0xBDCB, 0xAC42, 0x9ED9, 0x8F50, 0xFBEF, 0xEA66, 0xD8FD, 0xC974,
    0x4204, 0x538D, 0x6116, 0x709F, 0x0420, 0x15A9, 0x2732, 0x36BB,
    0xCE4C, 0xDFC5, 0xED5E, 0xFCD7, 0x8868, 0x99E1, 0xAB7A, 0xBAF3,
    0x5285, 0x430C, 0x7197, 0x601E, 0x14A1, 0x0528, 0x37B3, 0x263A,
    0xDECD, 0xCF44, 0xFDDF, 0xEC56, 0x98E9, 0x8960, 0xBBFB, 0xAA72,
    0x6306, 0x728F, 0x4014, 0x519D, 0x2522, 0x34AB, 0x0630, 0x17B9,
    0xEF4E, 0xFEC7, 0xCC5C, 0xDDD5, 0xA96A, 0xB8E3, 0x8A78, 0x9BF1,
    0x7387, 0x620E, 0x5095, 0x411C, 0x35A3, 0x242A, 0x16B1, 0x0738,
    0xFFCF, 0xEE46, 0xDCDD, 0xCD54, 0xB9EB, 0xA862, 0x9AF9, 0x8B70,
    0x8408, 0x9581, 0xA71A, 0xB693, 0xC22C, 0xD3A5, 0xE13E, 0xF0B7,
    0x0840, 0x19C9, 0x2B52, 0x3ADB, 0x4E64, 0x5FED, 0x6D76, 0x7CFF,
    0x9489, 0x8500, 0xB79B, 0xA612, 0xD2AD, 0xC324, 0xF1BF, 0xE036,
    0x18C1, 0x0948, 0x3BD3, 0x2A5A, 0x5EE5, 0x4F6C, 0x7DF7, 0x6C7E,
    0xA50A, 0xB483, 0x8618, 0x9791, 0xE32E, 0xF2A7, 0xC03C, 0xD1B5,
    0x2942, 0x38CB, 0x0A50, 0x1BD9, 0x6F66, 0x7EEF, 0x4C74, 0x5DFD,
    0xB58B, 0xA402, 0x9699, 0x8710, 0xF3AF, 0xE226, 0xD0BD, 0xC134,
    0x39C3, 0x284A, 0x1AD1, 0x0B58, 0x7FE7, 0x6E6E, 0x5CF5, 0x4D7C,
    0xC60C, 0xD785, 0xE51E, 0xF497, 0x8028, 0x91A1, 0xA33A, 0xB2B3,
    0x4A44, 0x5BCD, 0x6956, 0x78DF, 0x0C60, 0x1DE9, 0x2F72, 0x3EFB,
    0xD68D, 0xC704, 0xF59F, 0xE416, 0x90A9, 0x8120, 0xB3BB, 0xA232,
    0x5AC5, 0x4B4C, 0x79D7, 0x685E, 0x1CE1, 0x0D68, 0x3FF3, 0x2E7A,
    0xE70E, 0xF687, 0xC41C, 0xD595, 0xA12A, 0xB0A3, 0x8238, 0x93B1,
    0x6B46, 0x7ACF, 0x4854, 0x59DD, 0x2D62, 0x3CEB, 0x0E70, 0x1FF9,
    0xF78F, 0xE606, 0xD49D, 0xC514, 0xB1AB, 0xA022, 0x92B9, 0x8330,
    0x7BC7, 0x6A4E, 0x58D5, 0x495C, 0x3DE3, 0x2C6A, 0x1EF1, 0x0F78
];

let fcs = parseInt("FFFF", 16);
let i = 0;

while (i < hexString.length) {
    let strHexNumber = hexString.substring(i, i + 2);
    let intNumber = parseInt(strHexNumber, 16);
    let crc16tabIndex = (fcs ^ intNumber) & parseInt("FF", 16);
    fcs = (fcs >> 8) ^ table[crc16tabIndex];
    i = i + 2;
}

    return fcs ^ 0xFFFF;
};

module.exports = crc16itu;