原创 Arduino网络时钟客户端

升级！

增加了12h/24h 的开关，还有标准/ 夏令时开关！见步骤7 & 步骤8。

你是否曾想要一个和办公室时间来源完全准确的表？

这就有一个网络的办公时间服务器，你可以依据它并同步你的时间。大多数人用电脑来进行设置，现在Arduino也可以同样做到。（GPS时间客户端，详见 http://arduinotronics.blogspot.com/2014/03/gps-on-lcd.html）

你只需要一个Arduino和一个以太网插板，但是我们也加一个LCD显示屏。随后可能还增加闹钟功能。

Arduino UNO
Arduino Ethernet Shield

可选：

串口 LCD 显示屏 

步骤1：连接硬件

首先，记下印在以太网插板顶端的MAC地址。你接下来会用到。

看起来像 90 A2 DA 00 23 36，但是在代码中插入需要变成 0×90,0xA2，0xDA，0×00,0×23,0×36.

将以太网插板查到Arduino UNO顶部。用一根网线把它连到路由器上。

步骤2：代码

只需要在Arduino库文件夹下额外安装一个库。那就是 Time Library，可找 http://www.pjrc.com/teensy/td_libs_Time.html。

你讲需要以太网插板顶部的那个MAC地址，但是IP，网关，子网掩码都可以通过DHCP获得。你还需要时间服务器地址（见下面步骤）。

需要下载到Arduino上的程序如下：

//sample code originated at http://www.openreefs.com/ntpServer
//modified by Steve Spence, http://arduinotronics.blogspot.com

#include
#include
#include
#include

/* ******** Ethernet Card Settings ******** */
// Set this to your Ethernet Card Mac Address
byte mac[] = { 0×90, 0xA2, 0xDA, 0×00, 0×23, 0×36 };

/* ******** NTP Server Settings ******** */
/* us.pool.ntp.org NTP server
(Set to your time server of choice) */
IPAddress timeServer(216, 23, 247, 62);

/* Set this to the offset (in seconds) to your local time
This_example is GMT – 4 */
const long timeZoneOffset = -14400L;

/* Syncs to NTP server every 15 seconds for testing,
set to 1 hour or more to be reasonable */
unsigned int ntpSyncTime = 3600;

/* ALTER THESE VARIABLES AT YOUR OWN RISK */
// local port to listen for UDP packets
unsigned int localPort = 8888;
// NTP time stamp is in the first 48 bytes of the message
const int NTP_PACKET_SIZE= 48;
// Buffer to hold incoming and outgoing packets
byte packetBuffer[NTP_PACKET_SIZE];
// A UDP instance to let us send and receive packets over UDP
EthernetUDP Udp;
// Keeps track of how long ago we updated the NTP server
unsigned long ntpLastUpdate = 0;
// Check last time clock displayed (Not in Production)
time_t prevDisplay = 0;

void setup() {
Serial.begin(9600);

// Ethernet shield and NTP setup
int i = 0;
int DHCP = 0;
DHCP = Ethernet.begin(mac);
//Try to get dhcp settings 30 times before giving up
while( DHCP == 0 && i < 30){
delay(1000);
DHCP = Ethernet.begin(mac);
i++;
}
if(!DHCP){
Serial.println(“DHCP FAILED”);
for(;;); //Infinite loop because DHCP Failed
}
Serial.println(“DHCP Success”);

//Try to get the date and time
int trys=0;
while(!getTimeAndDate() && trys<10) {
trys++;
}
}

// Do not alter this function, it is used by the system
int getTimeAndDate() {
int flag=0;
Udp.begin(localPort);
sendNTPpacket(timeServer);
delay(1000);
if (Udp.parsePacket()){
Udp.read(packetBuffer,NTP_PACKET_SIZE);  // read the packet into the buffer
unsigned long highWord, lowWord, epoch;
highWord = word(packetBuffer[40], packetBuffer[41]);
lowWord = word(packetBuffer[42], packetBuffer[43]);
epoch = highWord << 16 | lowWord;
epoch = epoch – 2208988800 + timeZoneOffset;
flag=1;
setTime(epoch);
ntpLastUpdate = now();
}
return flag;
}

// Do not alter this function, it is used by the system
unsigned long sendNTPpacket(IPAddress& address)
{
memset(packetBuffer, 0, NTP_PACKET_SIZE);
packetBuffer[0] = 0b11100011;
packetBuffer[1] = 0;
packetBuffer[2] = 6;
packetBuffer[3] = 0xEC;
packetBuffer[12]  = 49;
packetBuffer[13]  = 0x4E;
packetBuffer[14]  = 49;
packetBuffer[15]  = 52;
Udp.beginPacket(address, 123);
Udp.write(packetBuffer,NTP_PACKET_SIZE);
Udp.endPacket();
}

// Clock display of the time and date (Basic)
void clockDisplay(){
Serial.print(hour());
printDigits(minute());
printDigits(second());
Serial.print(” “);
Serial.print(day());
Serial.print(” “);
Serial.print(month());
Serial.print(” “);
Serial.print(year());
Serial.println();
}

// Utility function for clock display: prints preceding colon and leading 0
void printDigits(int digits){
Serial.print(“:”);
if(digits < 10)
Serial.print(’0′);
Serial.print(digits);
}

// This is where all the magic happens…
void loop() {
// Update the time via NTP server as often as the time you set at the top
if(now()-ntpLastUpdate > ntpSyncTime) {
int trys=0;
while(!getTimeAndDate() && trys<10){
trys++;
}
if(trys<10){
Serial.println(“ntp server update success”);
}
else{
Serial.println(“ntp server update failed”);
}
}

// Display the time if it has changed by more than a second.
if( now() != prevDisplay){
prevDisplay = now();
clockDisplay();
}
}

继续阅读：http://wiznetbj.cafe24.com/?p=6367