15-ESP8266 SDK开发基础入门篇--上位机串口控制 Wi-Fi输出PWM的占空比,上位机程序编写

        /// <CRC  效验  >
        /// 
        /// </summary>
        /// <param name="modbusdata"></param>
        /// <param name="length"></param>
        /// <returns></returns>
        private int crc16_modbus(byte[] modbusdata, int length)
        {
            int i, j;

            int crc = 0xffff;

            try
            {
                for (i = 0; i < length; i++)
                {
                    crc ^= modbusdata[i];
                    for (j = 0; j < 8; j++)
                    {
                        if ((crc & 0x01) == 1)
                        {
                            crc = (crc >> 1) ^ 0xa001;
                        }
                        else
                        {
                            crc >>= 1;
                        }
                    }
                }
            }
            catch (Exception)
            {
                
                throw;
            }
            
            return crc;
        }

        /*
          modbusdata   要校验的数据
          length       数据长度
          返回值 1 正确  0 错误
        */
        private int crc16_flage(byte[] modbusdata, int length)
        {
            int Receive_CRC = 0, calculation = 0;//接收到的CRC,计算的CRC

            Receive_CRC = crc16_modbus(modbusdata, length);
            calculation = modbusdata[length + 1];
            calculation <<= 8;
            calculation += modbusdata[length];
            if (calculation != Receive_CRC)
            {
                return 0;
            }
            return 1;
        }