张高兴的 .NET IoT 入门指南：（八）基于 GPS 的 NTP 时间同步服务器
时间究竟是什么？这既可以是一个哲学问题，也可以是一个物理问题。古人对太阳进行观测，利用太阳的投影发明了日晷，定义了最初的时间。随着科技的发展，天文观测的精度也越来越准确，人们发现地球的自转并不是完全一致的，这就导致每天经过的时间是不一样的。这点误差对于基本生活基本没有影响，但是对于股票交易、火箭发射等等要求高精度时间的场景就无法忍受了。科学家们开始把观测转移到了微观世界，找到了一种运动高度稳定的原子——铯，最终定义出了准确的时间：铯原子电子跃迁 9192631770 个周期所持续的时间长度定义为 1 秒。基于这个定义制造出了高度稳定的原子钟。时间在计算机中又是如何定义的呢？通常使用 Unix 时间戳进行表示，记录的是自公元 1970 年 1 月 1 日 0 时 0 分 0 秒以来的秒数。计算机为了维持时钟的走时，硬件层面使用晶体振荡器保障时钟的精确性（也是石英钟的原理），操作系统层面使用时钟中断去更新时间的流逝。现代计算机的硬件设计通常有独立的时钟（RTC），这源于 Intel 和微软创立的标准 High Precision Event Timer（HPET），标准指定了 10 MHz 的时钟速度，因此时钟可以获得 100 纳秒的分辨率。这也是 .NET 时间有关的类型中 Ticks 属性的由来，1秒 = 10000000 Ticks。虽然计算机的时钟已经足够精准，但也会受到环境温度的影响造成过快或者过慢的问题。为了对计算机的时钟进行校准，通常使用 NTP 协议与网络中的时间服务器进行同步。时间服务器的时间又会使用 GPS 接收机、无线电或者是原子钟进行校准。
本文将从 GPS 时间的获取、NTP 报文的编写实现一个“玩具”级别的时间同步服务器，使用 .NET 6 编写一个控制台应用程序，通过本文你可以学到：
[*]串口 SerialPort 类的使用；
[*]使用 Socket 类实现 UDP 的监听与回复；
[*]在程序中使用 Process 类执行命令行指令；
[*]了解 GPS 数据报文的 NMEA-0183 协议；
[*]了解 NTP 协议报文。
https://img2022.cnblogs.com/blog/1085877/202208/1085877-20220805140738478-904831808.jpg
[*]硬件需求
[*]电路
[*]GPS 数据报文的 NMEA-0183 协议
[*]NTP 协议报文
[*]编写代码
[*]项目结构
[*]项目依赖
[*]配置串口读取 GPS 数据
[*]实现 NTP 服务
[*]部署应用
[*]发布到文件
[*]构建 Docker 镜像
[*]后续工作
硬件需求
名称描述数量计算机可以是运行 Linux 的开发板，也可以是运行 Windows 的电脑x1NEO-6MGPS 模块x1USB 串口可选，使用 USB 串口将 GPS 模块与计算机相连x1杜邦线传感器与开发板的连接线若干电路
https://img2022.cnblogs.com/blog/1085877/202208/1085877-20220805140802721-1489388097.jpg
传感器接口开发板接口NEO-6MTX开发板或 USB 串口的RXRX开发板或 USB 串口的TXVCC5VGNDGNDGPS 数据报文的 NMEA-0183 协议
NMEA-0183 是 GPS 设备输出信息的标准格式，是由美国国家海洋电子协会（National Marine Electronics Association）定制的标准。NMEA-0183 有多种不同的数据报文，每种都是独立的 ASCII 字符串，使用逗号隔开数据，数据流长度从 30-100 字符不等，通常以每秒间隔选择输出。NMEA-0183 协议定义的语句非常多，但是常用的或者说兼容性最广的语句只有 $GPGGA、$GPGSA、$GPGSV、$GPRMC、$GPVTG 等。下面给出这些常用 NMEA-0183 语句的解释。
帧名称说明最大帧长$GPGGA全球定位数据72$GPGSA卫星 PRN 数据65$GPGSV卫星状态信息210$GPRMC推荐最小数据70$GPVTG地面速度信息34由于我们只需要从 GPS 中获取时间信息，选择包含时间信息的 “$GPRMC 推荐最小数据”帧进行解析：
$GPRMC*帧头UTC 时间定位状态纬度纬度半球经度经度半球地面速率地面航向UTC 日期磁偏角磁偏角方向模式 * 校验和下面以一个真实的数据帧为例 $GPRMC,013717.00,A,3816.57392,N,10708.73951,E,0.467,,050722,,,A*78：
$GPRMC013717.00A3816.57392N10708.73951E0.467050722A*78帧头UTC 时间 01:37:17A=有效定位，V=无效定位纬度 38 度 16.57392 分北纬经度 107 度 8.73951 分东经地面速率 0.467 节航向 度UTC 日期 2022/07/05磁偏角 度磁偏角方向A=自主定位，N=数据无效因此，通过串口读取 $GPRMC 数据帧后，需要解析和字段的值，并将其转换为 UTC 时间。
细心的你也许会发现获取到的时间信息只精确到秒，GPS 明明使用的是原子钟，这是为什么？仔细观察手中的 GPS 模块，还有一个 PPS 针脚没有使用。PPS（Pulse Per Second）是秒脉冲，一般是由 GPS 接收机或原子钟按秒发出的、宽度小于1秒、有着急升或突降边沿的脉冲信号，通常用于精确计时和测量时间。PPS 信号能精确地（亚毫秒级）指示每一秒的开始时间，但不能指示对应现实时间的哪一秒，因此只能作为辅助信号，与卫星导航信息组合使用，提供低延迟、低抖动的授时服务。很遗憾，.NET 目前没法直接操作 PPS 引脚，我们只能实现一个“玩具”级的时间同步服务器了。
NTP 协议报文
NTP（Network Time Protocol），网络时间协议，是一种使用 UDP 的计算机之间进行时间同步的网络协议，位于 OSI 7 层网络模型中的应用层，默认使用的端口为 123。那么使用 NTP 是如何进行时间同步的呢？简单的说将发送的报文打上本机的时间戳，配合报文来回传输的时延修正本机的时间。如下图所示，可以计算出网络传输时延 \(\delta\)，以及客户端与服务端的时间偏移 \(\theta\)：
https://img2022.cnblogs.com/blog/1085877/202208/1085877-20220805140811836-652569601.jpg
\(\delta=(t_3-t_0)-(t_2-t_1)\)
\(\theta=\frac{(t_1-t_0)+(t_2-t_3)}{2}\)
其中，\(t_0\) 是请求报文传输的客户端时间戳，\(t_1\) 是请求报文接收的服务器时间戳，\(t_2\) 是回复报文传输的服务器时间戳，\(t_3\) 是回复报文接收的客户端时间戳。客户端和服务端都有一个时间轴，分别代表着各自系统的时间，当客户端想要同步服务端的时间时，客户端会构造一个 NTP 报文发送到服务端，客户端会记下此时发送的时间 \(t_0\)，经过一段网络延时传输后，服务器在 \(t_1\) 时刻收到报文，经过一段时间处理后在 \(t_2\) 时刻向客户端返回报文，再经过一段网络延时传输后客户端在 \(t_3\) 时刻收到服务器报文。这样客户端就可以校准自己的本机时间了。
在了解 NTP 同步时间的过程后，下面解析 NTP 报文具体包含的字段，一般的 NTP 报文长度为 48 字节：
字段说明LI闰秒指示，2bitVersionNTP 版本，3bitMode工作模式，3bit ，客户端=0b011，服务器=0b100Stratum时钟层数，8bit，层数为 0 的设备为高精度的时钟（如原子钟），层数为 1 的设备与层数 0 的设备直接相连，……Poll Interval轮询时间，8bit，连续 NTP 报文之间的最大时间间隔Precision时钟精度，8bitRoot Delay根时延，32bit，表示在主参考源之间往返的总共时延Root Dispersion根离散，32bit，相对于主参考源的标称误差Reference ID参考源的标识，32bit，4 个字符或 IP 地址Reference Timestamp参考时间戳，64bit，本地时钟最后一次被更新的时间| Originate Timestamp | 原始时间戳 \(t_0\)，64bit，客户端发送的时间 |
| Receive Timestamp | 接受时间戳 \(t_1\)，64bit，服务端接受到的时间 |
| Transmit Timestamp | 传送时间戳 \(t_2\)，64bit，服务端发送的时间 |
其中要注意的是 NTP 时间戳的起始时间是 1900-01-01 00:00:00，而不是 Unix 时间戳的起始时间 1970-01-01 00:00:00。
下面是使用 Wireshark 抓取的 Windows 时钟同步的 NTP 报文：
https://img2022.cnblogs.com/blog/1085877/202208/1085877-20220805140829666-1078800413.jpg
编写代码
项目地址：https://github.com/ZhangGaoxing/gps-ntp
项目结构
创建一个控制台应用和类库，项目结构如下：
https://img2022.cnblogs.com/blog/1085877/202208/1085877-20220805140836682-1474503350.jpg
项目依赖
添加如下 NuGet 包引用：
<ItemGroup>
<PackageReference Include="System.IO.Ports" Version="6.0.0" />
</ItemGroup>配置串口读取 GPS 数据
绝大部分 GPS 模块每秒会通过串口输出 NMEA-0183 协议报文，因此我们只需要通过串口读取需要的时间数据即可。此环节包含 3 个步骤：
[*]初始化串口；
[*]读取 $GPRMC 数据帧的内容，提取时间信息；
[*]更新系统时间。
初始化串口
使用串口时最重要的属性是波特率，请查阅对应 GPS 模块的数据手册，这里使用的 NEO-6M 模块的波特率是 9600。串口的名称取决于你的连接方式，在 Linux 中串口对应的驱动文件在 /dev 目录下，使用内置串口可能的文件名称为 ttySx，使用 USB 串口可能的文件名称为 ttyUSBx，在 Windows 中串口的名称为 COMx，其中 x 表示的是数字编号。
// 使用的串口名称const string SERIAL_NAME = "/dev/ttyUSB0";using SerialPort gps = new SerialPort(SERIAL_NAME){<ItemGroup>
<PackageReference Include="System.IO.Ports" Version="6.0.0" />
</ItemGroup> BaudRate = 9600,<ItemGroup>
<PackageReference Include="System.IO.Ports" Version="6.0.0" />
</ItemGroup> Encoding = Encoding.UTF8,<ItemGroup>
<PackageReference Include="System.IO.Ports" Version="6.0.0" />
</ItemGroup> ReadTimeout = 500,<ItemGroup>
<PackageReference Include="System.IO.Ports" Version="6.0.0" />
</ItemGroup> WriteTimeout = 500,};从串口中获取数据
从串口中读取数据时使用的是 SerialPort 类中的 DataReceived 事件。事件（event）可以理解为一种广播，当完成某种操作后向外发送通知。即串口接收到数据后，触发数据处理事件。
gps.DataReceived += GpsFrameReceived;/// /// GPS 报文处理/// void GpsFrameReceived(object sender, SerialDataReceivedEventArgs e){<ItemGroup>
<PackageReference Include="System.IO.Ports" Version="6.0.0" />
</ItemGroup> // TODO：读取 `$GPRMC` 数据帧；提取时间；更新系统时间}由于 GPS 模块输出的不只有 $GPRMC 数据帧，因此需要在处理事件中判断帧头以及帧的有效性。
void GpsFrameReceived(object sender, SerialDataReceivedEventArgs e){<ItemGroup>
<PackageReference Include="System.IO.Ports" Version="6.0.0" />
</ItemGroup> string frame = gps.ReadLine();<ItemGroup>
<PackageReference Include="System.IO.Ports" Version="6.0.0" />
</ItemGroup> if (frame.StartsWith("$GPRMC"))<ItemGroup>
<PackageReference Include="System.IO.Ports" Version="6.0.0" />
</ItemGroup> {<ItemGroup>
<PackageReference Include="System.IO.Ports" Version="6.0.0" />
</ItemGroup><ItemGroup>
<PackageReference Include="System.IO.Ports" Version="6.0.0" />
</ItemGroup>// $GPRMC,UTC 时间,定位状态,纬度,纬度半球,经度,经度半球,速度,航向,UTC 日期,磁偏角,磁偏角方向,指示模式*校验和<ItemGroup>
<PackageReference Include="System.IO.Ports" Version="6.0.0" />
</ItemGroup><ItemGroup>
<PackageReference Include="System.IO.Ports" Version="6.0.0" />
</ItemGroup>// $GPRMC,013717.00,A,3816.57392,N,10708.73951,E,0.467,,050722,,,A*78<ItemGroup>
<PackageReference Include="System.IO.Ports" Version="6.0.0" />
</ItemGroup><ItemGroup>
<PackageReference Include="System.IO.Ports" Version="6.0.0" />
</ItemGroup>string[] field = frame.Split(',');<ItemGroup>
<PackageReference Include="System.IO.Ports" Version="6.0.0" />
</ItemGroup><ItemGroup>
<PackageReference Include="System.IO.Ports" Version="6.0.0" />
</ItemGroup>// 帧数据有效<ItemGroup>
<PackageReference Include="System.IO.Ports" Version="6.0.0" />
</ItemGroup><ItemGroup>
<PackageReference Include="System.IO.Ports" Version="6.0.0" />
</ItemGroup>if (!field.StartsWith("N"))<ItemGroup>
<PackageReference Include="System.IO.Ports" Version="6.0.0" />
</ItemGroup><ItemGroup>
<PackageReference Include="System.IO.Ports" Version="6.0.0" />
</ItemGroup>{<ItemGroup>
<PackageReference Include="System.IO.Ports" Version="6.0.0" />
</ItemGroup><ItemGroup>
<PackageReference Include="System.IO.Ports" Version="6.0.0" />
</ItemGroup><ItemGroup>
<PackageReference Include="System.IO.Ports" Version="6.0.0" />
</ItemGroup><ItemGroup>
<PackageReference Include="System.IO.Ports" Version="6.0.0" />
</ItemGroup>// TODO：提取时间；更新系统时间<ItemGroup>
<PackageReference Include="System.IO.Ports" Version="6.0.0" />
</ItemGroup><ItemGroup>
<PackageReference Include="System.IO.Ports" Version="6.0.0" />
</ItemGroup>}<ItemGroup>
<PackageReference Include="System.IO.Ports" Version="6.0.0" />
</ItemGroup> }}在验证 $GPRMC 数据帧有效后，根据帧解析提取对应字段的时间信息。
void GpsFrameReceived(object sender, SerialDataReceivedEventArgs e){<ItemGroup>
<PackageReference Include="System.IO.Ports" Version="6.0.0" />
</ItemGroup> string frame = gps.ReadLine();<ItemGroup>
<PackageReference Include="System.IO.Ports" Version="6.0.0" />
</ItemGroup> if (frame.StartsWith("$GPRMC"))<ItemGroup>
<PackageReference Include="System.IO.Ports" Version="6.0.0" />
</ItemGroup> {<ItemGroup>
<PackageReference Include="System.IO.Ports" Version="6.0.0" />
</ItemGroup><ItemGroup>
<PackageReference Include="System.IO.Ports" Version="6.0.0" />
</ItemGroup>string[] field = frame.Split(',');<ItemGroup>
<PackageReference Include="System.IO.Ports" Version="6.0.0" />
</ItemGroup><ItemGroup>
<PackageReference Include="System.IO.Ports" Version="6.0.0" />
</ItemGroup>if (!field.StartsWith("N"))<ItemGroup>
<PackageReference Include="System.IO.Ports" Version="6.0.0" />
</ItemGroup><ItemGroup>
<PackageReference Include="System.IO.Ports" Version="6.0.0" />
</ItemGroup>{<ItemGroup>
<PackageReference Include="System.IO.Ports" Version="6.0.0" />
</ItemGroup><ItemGroup>
<PackageReference Include="System.IO.Ports" Version="6.0.0" />
</ItemGroup><ItemGroup>
<PackageReference Include="System.IO.Ports" Version="6.0.0" />
</ItemGroup><ItemGroup>
<PackageReference Include="System.IO.Ports" Version="6.0.0" />
</ItemGroup>// 获取 GPS 时间<ItemGroup>
<PackageReference Include="System.IO.Ports" Version="6.0.0" />
</ItemGroup><ItemGroup>
<PackageReference Include="System.IO.Ports" Version="6.0.0" />
</ItemGroup><ItemGroup>
<PackageReference Include="System.IO.Ports" Version="6.0.0" />
</ItemGroup><ItemGroup>
<PackageReference Include="System.IO.Ports" Version="6.0.0" />
</ItemGroup>string time = field;<ItemGroup>
<PackageReference Include="System.IO.Ports" Version="6.0.0" />
</ItemGroup><ItemGroup>
<PackageReference Include="System.IO.Ports" Version="6.0.0" />
</ItemGroup><ItemGroup>
<PackageReference Include="System.IO.Ports" Version="6.0.0" />
</ItemGroup><ItemGroup>
<PackageReference Include="System.IO.Ports" Version="6.0.0" />
</ItemGroup>string date = field;<ItemGroup>
<PackageReference Include="System.IO.Ports" Version="6.0.0" />
</ItemGroup><ItemGroup>
<PackageReference Include="System.IO.Ports" Version="6.0.0" />
</ItemGroup><ItemGroup>
<PackageReference Include="System.IO.Ports" Version="6.0.0" />
</ItemGroup><ItemGroup>
<PackageReference Include="System.IO.Ports" Version="6.0.0" />
</ItemGroup>DateTime utcNow = DateTime.ParseExact($"{date}{time}", "ddMMyyHHmmss", CultureInfo.InvariantCulture);<ItemGroup>
<PackageReference Include="System.IO.Ports" Version="6.0.0" />
</ItemGroup><ItemGroup>
<PackageReference Include="System.IO.Ports" Version="6.0.0" />
</ItemGroup><ItemGroup>
<PackageReference Include="System.IO.Ports" Version="6.0.0" />
</ItemGroup><ItemGroup>
<PackageReference Include="System.IO.Ports" Version="6.0.0" />
</ItemGroup>// TODO：更新系统时间<ItemGroup>
<PackageReference Include="System.IO.Ports" Version="6.0.0" />
</ItemGroup><ItemGroup>
<PackageReference Include="System.IO.Ports" Version="6.0.0" />
</ItemGroup>}<ItemGroup>
<PackageReference Include="System.IO.Ports" Version="6.0.0" />
</ItemGroup> }}更新系统时间
由于 .NET 并不提供修改系统时间的操作，因此我们要使用间接的方式修改系统时间。一种方式是使用 P/Invoke 调用 C++ 的函数，这种方式可以精确的修改时间，但涉及引用、数据类型转换，过于复杂，和本入门指南不符。这里使用的是运行命令行指令的方式修改系统的时间，但修改时间的精度只能精确到秒。在 Windows 中使用 PowerShell 的 Set-Date 命令，在 Linux 中使用 date 命令。
/// /// 更新系统时间/// void UpdateSystemTime(DateTime time){<ItemGroup>
<PackageReference Include="System.IO.Ports" Version="6.0.0" />
</ItemGroup> ProcessStartInfo processInfo;<ItemGroup>
<PackageReference Include="System.IO.Ports" Version="6.0.0" />
</ItemGroup> if (RuntimeInformation.IsOSPlatform(OSPlatform.Windows))<ItemGroup>
<PackageReference Include="System.IO.Ports" Version="6.0.0" />
</ItemGroup> {<ItemGroup>
<PackageReference Include="System.IO.Ports" Version="6.0.0" />
</ItemGroup><ItemGroup>
<PackageReference Include="System.IO.Ports" Version="6.0.0" />
</ItemGroup>processInfo = new ProcessStartInfo<ItemGroup>
<PackageReference Include="System.IO.Ports" Version="6.0.0" />
</ItemGroup><ItemGroup>
<PackageReference Include="System.IO.Ports" Version="6.0.0" />
</ItemGroup>{<ItemGroup>
<PackageReference Include="System.IO.Ports" Version="6.0.0" />
</ItemGroup><ItemGroup>
<PackageReference Include="System.IO.Ports" Version="6.0.0" />
</ItemGroup><ItemGroup>
<PackageReference Include="System.IO.Ports" Version="6.0.0" />
</ItemGroup><ItemGroup>
<PackageReference Include="System.IO.Ports" Version="6.0.0" />
</ItemGroup>FileName = "powershell.exe",<ItemGroup>
<PackageReference Include="System.IO.Ports" Version="6.0.0" />
</ItemGroup><ItemGroup>
<PackageReference Include="System.IO.Ports" Version="6.0.0" />
</ItemGroup><ItemGroup>
<PackageReference Include="System.IO.Ports" Version="6.0.0" />
</ItemGroup><ItemGroup>
<PackageReference Include="System.IO.Ports" Version="6.0.0" />
</ItemGroup>Arguments = $"Set-Date \"\"\"{time.ToLocalTime().ToString("yyyy-MM-dd HH:mm:ss")}\"\"\"",<ItemGroup>
<PackageReference Include="System.IO.Ports" Version="6.0.0" />
</ItemGroup><ItemGroup>
<PackageReference Include="System.IO.Ports" Version="6.0.0" />
</ItemGroup><ItemGroup>
<PackageReference Include="System.IO.Ports" Version="6.0.0" />
</ItemGroup><ItemGroup>
<PackageReference Include="System.IO.Ports" Version="6.0.0" />
</ItemGroup>RedirectStandardOutput = true,<ItemGroup>
<PackageReference Include="System.IO.Ports" Version="6.0.0" />
</ItemGroup><ItemGroup>
<PackageReference Include="System.IO.Ports" Version="6.0.0" />
</ItemGroup><ItemGroup>
<PackageReference Include="System.IO.Ports" Version="6.0.0" />
</ItemGroup><ItemGroup>
<PackageReference Include="System.IO.Ports" Version="6.0.0" />
</ItemGroup>UseShellExecute = false,<ItemGroup>
<PackageReference Include="System.IO.Ports" Version="6.0.0" />
</ItemGroup><ItemGroup>
<PackageReference Include="System.IO.Ports" Version="6.0.0" />
</ItemGroup><ItemGroup>
<PackageReference Include="System.IO.Ports" Version="6.0.0" />
</ItemGroup><ItemGroup>
<PackageReference Include="System.IO.Ports" Version="6.0.0" />
</ItemGroup>CreateNoWindow = true,<ItemGroup>
<PackageReference Include="System.IO.Ports" Version="6.0.0" />
</ItemGroup><ItemGroup>
<PackageReference Include="System.IO.Ports" Version="6.0.0" />
</ItemGroup>};<ItemGroup>
<PackageReference Include="System.IO.Ports" Version="6.0.0" />
</ItemGroup> }<ItemGroup>
<PackageReference Include="System.IO.Ports" Version="6.0.0" />
</ItemGroup> else<ItemGroup>
<PackageReference Include="System.IO.Ports" Version="6.0.0" />
</ItemGroup> {<ItemGroup>
<PackageReference Include="System.IO.Ports" Version="6.0.0" />
</ItemGroup><ItemGroup>
<PackageReference Include="System.IO.Ports" Version="6.0.0" />
</ItemGroup>processInfo = new ProcessStartInfo<ItemGroup>
<PackageReference Include="System.IO.Ports" Version="6.0.0" />
</ItemGroup><ItemGroup>
<PackageReference Include="System.IO.Ports" Version="6.0.0" />
</ItemGroup>{<ItemGroup>
<PackageReference Include="System.IO.Ports" Version="6.0.0" />
</ItemGroup><ItemGroup>
<PackageReference Include="System.IO.Ports" Version="6.0.0" />
</ItemGroup><ItemGroup>
<PackageReference Include="System.IO.Ports" Version="6.0.0" />
</ItemGroup><ItemGroup>
<PackageReference Include="System.IO.Ports" Version="6.0.0" />
</ItemGroup>FileName = "date",<ItemGroup>
<PackageReference Include="System.IO.Ports" Version="6.0.0" />
</ItemGroup><ItemGroup>
<PackageReference Include="System.IO.Ports" Version="6.0.0" />
</ItemGroup><ItemGroup>
<PackageReference Include="System.IO.Ports" Version="6.0.0" />
</ItemGroup><ItemGroup>
<PackageReference Include="System.IO.Ports" Version="6.0.0" />
</ItemGroup>Arguments = $"-s \"{time.ToLocalTime().ToString("yyyy-MM-dd HH:mm:ss")}\"",<ItemGroup>
<PackageReference Include="System.IO.Ports" Version="6.0.0" />
</ItemGroup><ItemGroup>
<PackageReference Include="System.IO.Ports" Version="6.0.0" />
</ItemGroup><ItemGroup>
<PackageReference Include="System.IO.Ports" Version="6.0.0" />
</ItemGroup><ItemGroup>
<PackageReference Include="System.IO.Ports" Version="6.0.0" />
</ItemGroup>RedirectStandardOutput = true,<ItemGroup>
<PackageReference Include="System.IO.Ports" Version="6.0.0" />
</ItemGroup><ItemGroup>
<PackageReference Include="System.IO.Ports" Version="6.0.0" />
</ItemGroup><ItemGroup>
<PackageReference Include="System.IO.Ports" Version="6.0.0" />
</ItemGroup><ItemGroup>
<PackageReference Include="System.IO.Ports" Version="6.0.0" />
</ItemGroup>UseShellExecute = false,<ItemGroup>
<PackageReference Include="System.IO.Ports" Version="6.0.0" />
</ItemGroup><ItemGroup>
<PackageReference Include="System.IO.Ports" Version="6.0.0" />
</ItemGroup><ItemGroup>
<PackageReference Include="System.IO.Ports" Version="6.0.0" />
</ItemGroup><ItemGroup>
<PackageReference Include="System.IO.Ports" Version="6.0.0" />
</ItemGroup>CreateNoWindow = true,<ItemGroup>
<PackageReference Include="System.IO.Ports" Version="6.0.0" />
</ItemGroup><ItemGroup>
<PackageReference Include="System.IO.Ports" Version="6.0.0" />
</ItemGroup>};<ItemGroup>
<PackageReference Include="System.IO.Ports" Version="6.0.0" />
</ItemGroup> }<ItemGroup>
<PackageReference Include="System.IO.Ports" Version="6.0.0" />
</ItemGroup> var process = Process.Start(processInfo);<ItemGroup>
<PackageReference Include="System.IO.Ports" Version="6.0.0" />
</ItemGroup> process.WaitForExit();}最终报文处理事件由以下代码构成：
void GpsFrameReceived(object sender, SerialDataReceivedEventArgs e){<ItemGroup>
<PackageReference Include="System.IO.Ports" Version="6.0.0" />
</ItemGroup> string frame = gps.ReadLine();<ItemGroup>
<PackageReference Include="System.IO.Ports" Version="6.0.0" />
</ItemGroup> if (frame.StartsWith("$GPRMC"))<ItemGroup>
<PackageReference Include="System.IO.Ports" Version="6.0.0" />
</ItemGroup> {<ItemGroup>
<PackageReference Include="System.IO.Ports" Version="6.0.0" />
</ItemGroup><ItemGroup>
<PackageReference Include="System.IO.Ports" Version="6.0.0" />
</ItemGroup>string[] field = frame.Split(',');<ItemGroup>
<PackageReference Include="System.IO.Ports" Version="6.0.0" />
</ItemGroup><ItemGroup>
<PackageReference Include="System.IO.Ports" Version="6.0.0" />
</ItemGroup>if (!field.StartsWith("N"))<ItemGroup>
<PackageReference Include="System.IO.Ports" Version="6.0.0" />
</ItemGroup><ItemGroup>
<PackageReference Include="System.IO.Ports" Version="6.0.0" />
</ItemGroup>{<ItemGroup>
<PackageReference Include="System.IO.Ports" Version="6.0.0" />
</ItemGroup><ItemGroup>
<PackageReference Include="System.IO.Ports" Version="6.0.0" />
</ItemGroup><ItemGroup>
<PackageReference Include="System.IO.Ports" Version="6.0.0" />
</ItemGroup><ItemGroup>
<PackageReference Include="System.IO.Ports" Version="6.0.0" />
</ItemGroup>string time = field;<ItemGroup>
<PackageReference Include="System.IO.Ports" Version="6.0.0" />
</ItemGroup><ItemGroup>
<PackageReference Include="System.IO.Ports" Version="6.0.0" />
</ItemGroup><ItemGroup>
<PackageReference Include="System.IO.Ports" Version="6.0.0" />
</ItemGroup><ItemGroup>
<PackageReference Include="System.IO.Ports" Version="6.0.0" />
</ItemGroup>string date = field;<ItemGroup>
<PackageReference Include="System.IO.Ports" Version="6.0.0" />
</ItemGroup><ItemGroup>
<PackageReference Include="System.IO.Ports" Version="6.0.0" />
</ItemGroup><ItemGroup>
<PackageReference Include="System.IO.Ports" Version="6.0.0" />
</ItemGroup><ItemGroup>
<PackageReference Include="System.IO.Ports" Version="6.0.0" />
</ItemGroup>DateTime utcNow = DateTime.ParseExact($"{date}{time}", "ddMMyyHHmmss", CultureInfo.InvariantCulture);<ItemGroup>
<PackageReference Include="System.IO.Ports" Version="6.0.0" />
</ItemGroup><ItemGroup>
<PackageReference Include="System.IO.Ports" Version="6.0.0" />
</ItemGroup><ItemGroup>
<PackageReference Include="System.IO.Ports" Version="6.0.0" />
</ItemGroup><ItemGroup>
<PackageReference Include="System.IO.Ports" Version="6.0.0" />
</ItemGroup>UpdateSystemTime(utcNow);<ItemGroup>
<PackageReference Include="System.IO.Ports" Version="6.0.0" />
</ItemGroup><ItemGroup>
<PackageReference Include="System.IO.Ports" Version="6.0.0" />
</ItemGroup><ItemGroup>
<PackageReference Include="System.IO.Ports" Version="6.0.0" />
</ItemGroup><ItemGroup>
<PackageReference Include="System.IO.Ports" Version="6.0.0" />
</ItemGroup>// 记录时钟最后一次被更新的时间<ItemGroup>
<PackageReference Include="System.IO.Ports" Version="6.0.0" />
</ItemGroup><ItemGroup>
<PackageReference Include="System.IO.Ports" Version="6.0.0" />
</ItemGroup><ItemGroup>
<PackageReference Include="System.IO.Ports" Version="6.0.0" />
</ItemGroup><ItemGroup>
<PackageReference Include="System.IO.Ports" Version="6.0.0" />
</ItemGroup>lastUpdatedTime = utcNow;<ItemGroup>
<PackageReference Include="System.IO.Ports" Version="6.0.0" />
</ItemGroup><ItemGroup>
<PackageReference Include="System.IO.Ports" Version="6.0.0" />
</ItemGroup>}<ItemGroup>
<PackageReference Include="System.IO.Ports" Version="6.0.0" />
</ItemGroup> }}使用 gps.Open(); 打开串口后就可以获取时间数据了。
实现 NTP 服务
下面使用 Socket 类实现一个简单的 UDP 服务器，用于监听和回复 NTP 报文。
初始化 UDP 服务
// NTP 服务初始化
using Socket ntpServer = new Socket(AddressFamily.InterNetwork, SocketType.Dgram, ProtocolType.Udp);
IPEndPoint ip = new IPEndPoint(IPAddress.Any, 123);
ntpServer.Bind(ip);监听和回复 NTP 报文
在后台新建一个进程用于监听 NTP 请求报文：
new Thread(NtpFrameReceived){<ItemGroup>
<PackageReference Include="System.IO.Ports" Version="6.0.0" />
</ItemGroup> IsBackground = true}.Start();/// /// NTP 报文接收与回复/// void NtpFrameReceived(){<ItemGroup>
<PackageReference Include="System.IO.Ports" Version="6.0.0" />
</ItemGroup> // 存储接收到的 NTP 请求报文<ItemGroup>
<PackageReference Include="System.IO.Ports" Version="6.0.0" />
</ItemGroup> Span receiveFrame = stackalloc byte;<ItemGroup>
<PackageReference Include="System.IO.Ports" Version="6.0.0" />
</ItemGroup> while (true)<ItemGroup>
<PackageReference Include="System.IO.Ports" Version="6.0.0" />
</ItemGroup> {<ItemGroup>
<PackageReference Include="System.IO.Ports" Version="6.0.0" />
</ItemGroup><ItemGroup>
<PackageReference Include="System.IO.Ports" Version="6.0.0" />
</ItemGroup>// 接收请求报文<ItemGroup>
<PackageReference Include="System.IO.Ports" Version="6.0.0" />
</ItemGroup><ItemGroup>
<PackageReference Include="System.IO.Ports" Version="6.0.0" />
</ItemGroup>EndPoint clientPoint = new IPEndPoint(IPAddress.Any, 0);<ItemGroup>
<PackageReference Include="System.IO.Ports" Version="6.0.0" />
</ItemGroup><ItemGroup>
<PackageReference Include="System.IO.Ports" Version="6.0.0" />
</ItemGroup>ntpServer.ReceiveFrom(receiveFrame, ref clientPoint);<ItemGroup>
<PackageReference Include="System.IO.Ports" Version="6.0.0" />
</ItemGroup><ItemGroup>
<PackageReference Include="System.IO.Ports" Version="6.0.0" />
</ItemGroup>DateTime receiveTime = DateTime.UtcNow;<ItemGroup>
<PackageReference Include="System.IO.Ports" Version="6.0.0" />
</ItemGroup><ItemGroup>
<PackageReference Include="System.IO.Ports" Version="6.0.0" />
</ItemGroup>// TODO：回复 NTP 报文<ItemGroup>
<PackageReference Include="System.IO.Ports" Version="6.0.0" />
</ItemGroup> }}根据帧解析生成 NTP 回复报文：
/// /// 生成 NTP 报文/// Span GenerateNtpFrame(Span receivedFrame, DateTime receiveTime){<ItemGroup>
<PackageReference Include="System.IO.Ports" Version="6.0.0" />
</ItemGroup> Span ntpFrame = stackalloc byte<ItemGroup>
<PackageReference Include="System.IO.Ports" Version="6.0.0" />
</ItemGroup> {<ItemGroup>
<PackageReference Include="System.IO.Ports" Version="6.0.0" />
</ItemGroup><ItemGroup>
<PackageReference Include="System.IO.Ports" Version="6.0.0" />
</ItemGroup>0x1c, 0x01, 0x11, 0xe9, 0x00, 0x00, 0x00, 0x00,<ItemGroup>
<PackageReference Include="System.IO.Ports" Version="6.0.0" />
</ItemGroup><ItemGroup>
<PackageReference Include="System.IO.Ports" Version="6.0.0" />
</ItemGroup>0x00, 0x01, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,<ItemGroup>
<PackageReference Include="System.IO.Ports" Version="6.0.0" />
</ItemGroup><ItemGroup>
<PackageReference Include="System.IO.Ports" Version="6.0.0" />
</ItemGroup>0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,<ItemGroup>
<PackageReference Include="System.IO.Ports" Version="6.0.0" />
</ItemGroup><ItemGroup>
<PackageReference Include="System.IO.Ports" Version="6.0.0" />
</ItemGroup>0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,<ItemGroup>
<PackageReference Include="System.IO.Ports" Version="6.0.0" />
</ItemGroup><ItemGroup>
<PackageReference Include="System.IO.Ports" Version="6.0.0" />
</ItemGroup>0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,<ItemGroup>
<PackageReference Include="System.IO.Ports" Version="6.0.0" />
</ItemGroup><ItemGroup>
<PackageReference Include="System.IO.Ports" Version="6.0.0" />
</ItemGroup>0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,<ItemGroup>
<PackageReference Include="System.IO.Ports" Version="6.0.0" />
</ItemGroup> };<ItemGroup>
<PackageReference Include="System.IO.Ports" Version="6.0.0" />
</ItemGroup> // Client Transmit Timestamp => Server Origin Timestamp<ItemGroup>
<PackageReference Include="System.IO.Ports" Version="6.0.0" />
</ItemGroup> for (int i = 0; i < 8; i++)<ItemGroup>
<PackageReference Include="System.IO.Ports" Version="6.0.0" />
</ItemGroup> {<ItemGroup>
<PackageReference Include="System.IO.Ports" Version="6.0.0" />
</ItemGroup><ItemGroup>
<PackageReference Include="System.IO.Ports" Version="6.0.0" />
</ItemGroup>ntpFrame = receivedFrame;<ItemGroup>
<PackageReference Include="System.IO.Ports" Version="6.0.0" />
</ItemGroup> }<ItemGroup>
<PackageReference Include="System.IO.Ports" Version="6.0.0" />
</ItemGroup> // 本机时钟最后更新时间<ItemGroup>
<PackageReference Include="System.IO.Ports" Version="6.0.0" />
</ItemGroup> long referenceTicks = (lastUpdatedTime - ntpStart).Ticks;<ItemGroup>
<PackageReference Include="System.IO.Ports" Version="6.0.0" />
</ItemGroup> uint referenceTimeInt = (uint)(referenceTicks / TICK_2_SECOND);<ItemGroup>
<PackageReference Include="System.IO.Ports" Version="6.0.0" />
</ItemGroup> uint referenceTimeFract = (uint)(referenceTicks % TICK_2_SECOND);<ItemGroup>
<PackageReference Include="System.IO.Ports" Version="6.0.0" />
</ItemGroup> var referenceTimeIntByte = BitConverter.GetBytes(referenceTimeInt);<ItemGroup>
<PackageReference Include="System.IO.Ports" Version="6.0.0" />
</ItemGroup> var referenceTimeFractByte = BitConverter.GetBytes(referenceTimeFract);<ItemGroup>
<PackageReference Include="System.IO.Ports" Version="6.0.0" />
</ItemGroup> // 接收报文时间<ItemGroup>
<PackageReference Include="System.IO.Ports" Version="6.0.0" />
</ItemGroup> long receiveTicks = (receiveTime - ntpStart).Ticks;<ItemGroup>
<PackageReference Include="System.IO.Ports" Version="6.0.0" />
</ItemGroup> uint receiveTimeInt = (uint)(receiveTicks / TICK_2_SECOND);<ItemGroup>
<PackageReference Include="System.IO.Ports" Version="6.0.0" />
</ItemGroup> uint receiveTimeFract = (uint)(receiveTicks % TICK_2_SECOND);<ItemGroup>
<PackageReference Include="System.IO.Ports" Version="6.0.0" />
</ItemGroup> var receiveTimeIntByte = BitConverter.GetBytes(receiveTimeInt);<ItemGroup>
<PackageReference Include="System.IO.Ports" Version="6.0.0" />
</ItemGroup> var receiveTimeFractByte = BitConverter.GetBytes(receiveTimeFract);<ItemGroup>
<PackageReference Include="System.IO.Ports" Version="6.0.0" />
</ItemGroup> // 发送报文时间<ItemGroup>
<PackageReference Include="System.IO.Ports" Version="6.0.0" />
</ItemGroup> long transmitTicks = (DateTime.UtcNow - ntpStart).Ticks;<ItemGroup>
<PackageReference Include="System.IO.Ports" Version="6.0.0" />
</ItemGroup> uint transmitTimeInt = (uint)(receiveTicks / TICK_2_SECOND);<ItemGroup>
<PackageReference Include="System.IO.Ports" Version="6.0.0" />
</ItemGroup> uint transmitTimeFract = (uint)(receiveTicks % TICK_2_SECOND);<ItemGroup>
<PackageReference Include="System.IO.Ports" Version="6.0.0" />
</ItemGroup> var transmitTimeIntByte = BitConverter.GetBytes(receiveTimeInt);<ItemGroup>
<PackageReference Include="System.IO.Ports" Version="6.0.0" />
</ItemGroup> var transmitTimeFractByte = BitConverter.GetBytes(receiveTimeFract);<ItemGroup>
<PackageReference Include="System.IO.Ports" Version="6.0.0" />
</ItemGroup> if (BitConverter.IsLittleEndian)<ItemGroup>
<PackageReference Include="System.IO.Ports" Version="6.0.0" />
</ItemGroup> {<ItemGroup>
<PackageReference Include="System.IO.Ports" Version="6.0.0" />
</ItemGroup><ItemGroup>
<PackageReference Include="System.IO.Ports" Version="6.0.0" />
</ItemGroup>for (int i = 0; i < 4; i++)<ItemGroup>
<PackageReference Include="System.IO.Ports" Version="6.0.0" />
</ItemGroup><ItemGroup>
<PackageReference Include="System.IO.Ports" Version="6.0.0" />
</ItemGroup>{<ItemGroup>
<PackageReference Include="System.IO.Ports" Version="6.0.0" />
</ItemGroup><ItemGroup>
<PackageReference Include="System.IO.Ports" Version="6.0.0" />
</ItemGroup><ItemGroup>
<PackageReference Include="System.IO.Ports" Version="6.0.0" />
</ItemGroup><ItemGroup>
<PackageReference Include="System.IO.Ports" Version="6.0.0" />
</ItemGroup>ntpFrame = referenceTimeIntByte;<ItemGroup>
<PackageReference Include="System.IO.Ports" Version="6.0.0" />
</ItemGroup><ItemGroup>
<PackageReference Include="System.IO.Ports" Version="6.0.0" />
</ItemGroup><ItemGroup>
<PackageReference Include="System.IO.Ports" Version="6.0.0" />
</ItemGroup><ItemGroup>
<PackageReference Include="System.IO.Ports" Version="6.0.0" />
</ItemGroup>ntpFrame = referenceTimeFractByte;<ItemGroup>
<PackageReference Include="System.IO.Ports" Version="6.0.0" />
</ItemGroup><ItemGroup>
<PackageReference Include="System.IO.Ports" Version="6.0.0" />
</ItemGroup><ItemGroup>
<PackageReference Include="System.IO.Ports" Version="6.0.0" />
</ItemGroup><ItemGroup>
<PackageReference Include="System.IO.Ports" Version="6.0.0" />
</ItemGroup>ntpFrame = receiveTimeIntByte;<ItemGroup>
<PackageReference Include="System.IO.Ports" Version="6.0.0" />
</ItemGroup><ItemGroup>
<PackageReference Include="System.IO.Ports" Version="6.0.0" />
</ItemGroup><ItemGroup>
<PackageReference Include="System.IO.Ports" Version="6.0.0" />
</ItemGroup><ItemGroup>
<PackageReference Include="System.IO.Ports" Version="6.0.0" />
</ItemGroup>ntpFrame = receiveTimeFractByte;<ItemGroup>
<PackageReference Include="System.IO.Ports" Version="6.0.0" />
</ItemGroup><ItemGroup>
<PackageReference Include="System.IO.Ports" Version="6.0.0" />
</ItemGroup><ItemGroup>
<PackageReference Include="System.IO.Ports" Version="6.0.0" />
</ItemGroup><ItemGroup>
<PackageReference Include="System.IO.Ports" Version="6.0.0" />
</ItemGroup>ntpFrame = transmitTimeIntByte;<ItemGroup>
<PackageReference Include="System.IO.Ports" Version="6.0.0" />
</ItemGroup><ItemGroup>
<PackageReference Include="System.IO.Ports" Version="6.0.0" />
</ItemGroup><ItemGroup>
<PackageReference Include="System.IO.Ports" Version="6.0.0" />
</ItemGroup><ItemGroup>
<PackageReference Include="System.IO.Ports" Version="6.0.0" />
</ItemGroup>ntpFrame = transmitTimeFractByte;<ItemGroup>
<PackageReference Include="System.IO.Ports" Version="6.0.0" />
</ItemGroup><ItemGroup>
<PackageReference Include="System.IO.Ports" Version="6.0.0" />
</ItemGroup>}<ItemGroup>
<PackageReference Include="System.IO.Ports" Version="6.0.0" />
</ItemGroup> }<ItemGroup>
<PackageReference Include="System.IO.Ports" Version="6.0.0" />
</ItemGroup> else<ItemGroup>
<PackageReference Include="System.IO.Ports" Version="6.0.0" />
</ItemGroup> {<ItemGroup>
<PackageReference Include="System.IO.Ports" Version="6.0.0" />
</ItemGroup><ItemGroup>
<PackageReference Include="System.IO.Ports" Version="6.0.0" />
</ItemGroup>for (int i = 0; i < 4; i++)<ItemGroup>
<PackageReference Include="System.IO.Ports" Version="6.0.0" />
</ItemGroup><ItemGroup>
<PackageReference Include="System.IO.Ports" Version="6.0.0" />
</ItemGroup>{<ItemGroup>
<PackageReference Include="System.IO.Ports" Version="6.0.0" />
</ItemGroup><ItemGroup>
<PackageReference Include="System.IO.Ports" Version="6.0.0" />
</ItemGroup><ItemGroup>
<PackageReference Include="System.IO.Ports" Version="6.0.0" />
</ItemGroup><ItemGroup>
<PackageReference Include="System.IO.Ports" Version="6.0.0" />
</ItemGroup>ntpFrame = referenceTimeIntByte;<ItemGroup>
<PackageReference Include="System.IO.Ports" Version="6.0.0" />
</ItemGroup><ItemGroup>
<PackageReference Include="System.IO.Ports" Version="6.0.0" />
</ItemGroup><ItemGroup>
<PackageReference Include="System.IO.Ports" Version="6.0.0" />
</ItemGroup><ItemGroup>
<PackageReference Include="System.IO.Ports" Version="6.0.0" />
</ItemGroup>ntpFrame = referenceTimeFractByte;<ItemGroup>
<PackageReference Include="System.IO.Ports" Version="6.0.0" />
</ItemGroup><ItemGroup>
<PackageReference Include="System.IO.Ports" Version="6.0.0" />
</ItemGroup><ItemGroup>
<PackageReference Include="System.IO.Ports" Version="6.0.0" />
</ItemGroup><ItemGroup>
<PackageReference Include="System.IO.Ports" Version="6.0.0" />
</ItemGroup>ntpFrame = receiveTimeIntByte;<ItemGroup>
<PackageReference Include="System.IO.Ports" Version="6.0.0" />
</ItemGroup><ItemGroup>
<PackageReference Include="System.IO.Ports" Version="6.0.0" />
</ItemGroup><ItemGroup>
<PackageReference Include="System.IO.Ports" Version="6.0.0" />
</ItemGroup><ItemGroup>
<PackageReference Include="System.IO.Ports" Version="6.0.0" />
</ItemGroup>ntpFrame = receiveTimeFractByte;<ItemGroup>
<PackageReference Include="System.IO.Ports" Version="6.0.0" />
</ItemGroup><ItemGroup>
<PackageReference Include="System.IO.Ports" Version="6.0.0" />
</ItemGroup><ItemGroup>
<PackageReference Include="System.IO.Ports" Version="6.0.0" />
</ItemGroup><ItemGroup>
<PackageReference Include="System.IO.Ports" Version="6.0.0" />
</ItemGroup>ntpFrame = transmitTimeIntByte;<ItemGroup>
<PackageReference Include="System.IO.Ports" Version="6.0.0" />
</ItemGroup><ItemGroup>
<PackageReference Include="System.IO.Ports" Version="6.0.0" />
</ItemGroup><ItemGroup>
<PackageReference Include="System.IO.Ports" Version="6.0.0" />
</ItemGroup><ItemGroup>
<PackageReference Include="System.IO.Ports" Version="6.0.0" />
</ItemGroup>ntpFrame = transmitTimeFractByte;<ItemGroup>
<PackageReference Include="System.IO.Ports" Version="6.0.0" />
</ItemGroup><ItemGroup>
<PackageReference Include="System.IO.Ports" Version="6.0.0" />
</ItemGroup>}<ItemGroup>
<PackageReference Include="System.IO.Ports" Version="6.0.0" />
</ItemGroup> }<ItemGroup>
<PackageReference Include="System.IO.Ports" Version="6.0.0" />
</ItemGroup> return ntpFrame.ToArray();}最终报文请求与回复由以下代码构成：
void NtpFrameReceived(){<ItemGroup>
<PackageReference Include="System.IO.Ports" Version="6.0.0" />
</ItemGroup> Span receiveFrame = stackalloc byte;<ItemGroup>
<PackageReference Include="System.IO.Ports" Version="6.0.0" />
</ItemGroup> while (true)<ItemGroup>
<PackageReference Include="System.IO.Ports" Version="6.0.0" />
</ItemGroup> {<ItemGroup>
<PackageReference Include="System.IO.Ports" Version="6.0.0" />
</ItemGroup><ItemGroup>
<PackageReference Include="System.IO.Ports" Version="6.0.0" />
</ItemGroup>EndPoint clientPoint = new IPEndPoint(IPAddress.Any, 0);<ItemGroup>
<PackageReference Include="System.IO.Ports" Version="6.0.0" />
</ItemGroup><ItemGroup>
<PackageReference Include="System.IO.Ports" Version="6.0.0" />
</ItemGroup>ntpServer.ReceiveFrom(receiveFrame, ref clientPoint);<ItemGroup>
<PackageReference Include="System.IO.Ports" Version="6.0.0" />
</ItemGroup><ItemGroup>
<PackageReference Include="System.IO.Ports" Version="6.0.0" />
</ItemGroup>DateTime receiveTime = DateTime.UtcNow;<ItemGroup>
<PackageReference Include="System.IO.Ports" Version="6.0.0" />
</ItemGroup><ItemGroup>
<PackageReference Include="System.IO.Ports" Version="6.0.0" />
</ItemGroup>// 回复 NTP 报文<ItemGroup>
<PackageReference Include="System.IO.Ports" Version="6.0.0" />
</ItemGroup><ItemGroup>
<PackageReference Include="System.IO.Ports" Version="6.0.0" />
</ItemGroup>Span sendFrame = GenerateNtpFrame(receiveFrame, DateTime.UtcNow);<ItemGroup>
<PackageReference Include="System.IO.Ports" Version="6.0.0" />
</ItemGroup><ItemGroup>
<PackageReference Include="System.IO.Ports" Version="6.0.0" />
</ItemGroup>ntpServer.SendTo(sendFrame, clientPoint);<ItemGroup>
<PackageReference Include="System.IO.Ports" Version="6.0.0" />
</ItemGroup><ItemGroup>
<PackageReference Include="System.IO.Ports" Version="6.0.0" />
</ItemGroup>DateTime sendTime = DateTime.UtcNow;<ItemGroup>
<PackageReference Include="System.IO.Ports" Version="6.0.0" />
</ItemGroup> }}将上述代码进行整合就构成了基于 GPS 的 NTP 时间同步服务器。
部署应用
发布到文件
[*]切换到 GpsNtp 项目运行发布命令：
dotnet publish -c release -r linux-x64 --no-self-contained
[*]将发布后的文件通过 FTP 等方式复制到 Linux 开发板；
[*]为 GpsNtp 文件增加可执行权限
sudo chmod +x GpsNtp
[*]运行程序
sudo ./GpsNtp构建 Docker 镜像
[*]在项目的根目录中创建 Dockerfile，并将整个项目复制到 Linux 开发板中：
FROM mcr.microsoft.com/dotnet/core/sdk:6.0-focal AS build
WORKDIR /app
# publish app
COPY src .
WORKDIR /app/GpsNtp
RUN dotnet restore
RUN dotnet publish -c release -r linux-arm -o out
# run app
FROM mcr.microsoft.com/dotnet/core/runtime:6.0-focal AS runtime
WORKDIR /app
COPY --from=build /app/GpsNtp/out ./
ENTRYPOINT ["dotnet", "GpsNtp.dll"]
[*]切换到项目目录，构建镜像：
docker build -t gps-ntp -f Dockerfile .
[*]运行镜像：
docker run --rm -it --device /dev/ttySx gps-ntp程序运行后，使用 Windows 时间同步服务进行一下测试。
https://img2022.cnblogs.com/blog/1085877/202208/1085877-20220805140852181-1943165619.jpg
免责声明：如果侵犯了您的权益，请联系站长，我们会及时删除侵权内容，谢谢合作！
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