C#上位机转换成Bt下发时间

long time=(now.ToUniversalTime().Ticks - 621355968000000000) / 10000000;
//时间戳
bt[x++] = (byte)(time >> 24);
bt[x++] = (byte)((time >> 16) & 0xFF);
bt[x++] = (byte)((time >> 8) & 0xFF);
bt[x++] = (byte)(time & 0xFF);