Ethernet 10BaseT/100BaseTX
Description
Ethernet functionality is available on the OI-Core module, featuring an embedded Wiznet W5500 chip. This allows for communication over any Ethernet network.
Communication between the micro-controller unit (MCU) and the Ethernet chip is facilitated through an SPI link. Example code for this setup is provided.
The W5500 chip serves as a Hardwired TCP/IP embedded Ethernet controller, simplifying Internet connectivity for embedded systems. It integrates a TCP/IP stack, 10/100 Ethernet MAC, and PHY.
Features of the W5500 chip include:
Support for Hardwired TCP/IP Protocols: TCP, UDP, ICMP, IPv4, ARP, IGMP, PPPoE
Simultaneous support for 8 independent sockets
Power-down mode and Wake on LAN over UDP functionality
Embedded 10BaseT/100BaseTX Ethernet PHY
Auto Negotiation support for full/half duplex and 10/100-based operation
Note
On OI-Core, ethernet does not support auto-MDIX feature. Thus, user should use straight-through cables to connect to other switches or routers and crossover cables to connect to devices such as servers, workstations or another W5500. However, user can use either type of cable to connect to other devices with auto-MDIX enabled, and the interface automatically corrects for any incorrect cabling.
Code examples
The example code above demonstrates how to get the time from a remote server.
/**
* @file EthernetUdpTime.cpp
* @brief Udp NTP Client
*
* Get the time from a Network Time Protocol (NTP) time server
* Demonstrates use of UDP sendPacket and ReceivePacket
* For more on NTP time servers and the messages needed to communicate with them,
* see http://en.wikipedia.org/wiki/Network_Time_Protocol
*
* created 4 Sep 2010
* by Michael Margolis
* modified 9 Apr 2012
* by Tom Igoe
* modified 02 Sept 2015
* by Arturo Guadalupi
*
* This code is in the public domain.
*/
#include <SPI.h>
#include <Ethernet.h>
#include <EthernetUdp.h>
// Enter a MAC address for your controller below.
// Newer Ethernet shields have a MAC address printed on a sticker on the shield
byte mac[] = {
0xDE, 0xAD, 0xBE, 0xEF, 0xFE, 0xED
};
unsigned int localPort = 8888; // local port to listen for UDP packets
const char timeServer[] = "time.nist.gov"; // time.nist.gov NTP server
const int NTP_PACKET_SIZE = 48; // NTP time stamp is in the first 48 bytes of the message
byte packetBuffer[NTP_PACKET_SIZE]; //buffer to hold incoming and outgoing packets
// A UDP instance to let us send and receive packets over UDP
EthernetUDP Udp;
void sendNTPpacket(const char * address);
void setup() {
Ethernet.init(ETHERNET_SS); // OI-Core pin Ethernet CS is GPIO_NUM_18
// Open serial communications and wait for port to open:
Serial.begin(115200);
// start Ethernet and UDP
if (Ethernet.begin(mac) == 0) {
Serial.println("Failed to configure Ethernet using DHCP");
// Check for Ethernet hardware present
if (Ethernet.hardwareStatus() == EthernetNoHardware) {
Serial.println("Ethernet shield was not found. Sorry, can't run without hardware. :(");
} else if (Ethernet.linkStatus() == LinkOFF) {
Serial.println("Ethernet cable is not connected.");
}
// no point in carrying on, so do nothing forevermore:
while (true) {
delay(1);
}
}
Udp.begin(localPort);
}
void loop() {
sendNTPpacket(timeServer); // send an NTP packet to a time server
// wait to see if a reply is available
delay(1000);
if (Udp.parsePacket()) {
// We've received a packet, read the data from it
Udp.read(packetBuffer, NTP_PACKET_SIZE); // read the packet into the buffer
// the timestamp starts at byte 40 of the received packet and is four bytes,
// or two words, long. First, extract the two words:
unsigned long highWord = word(packetBuffer[40], packetBuffer[41]);
unsigned long lowWord = word(packetBuffer[42], packetBuffer[43]);
// combine the four bytes (two words) into a long integer
// this is NTP time (seconds since Jan 1 1900):
unsigned long secsSince1900 = highWord << 16 | lowWord;
Serial.print("Seconds since Jan 1 1900 = ");
Serial.println(secsSince1900);
// now convert NTP time into everyday time:
Serial.print("Unix time = ");
// Unix time starts on Jan 1 1970. In seconds, that's 2208988800:
const unsigned long seventyYears = 2208988800UL;
// subtract seventy years:
unsigned long epoch = secsSince1900 - seventyYears;
// print Unix time:
Serial.println(epoch);
// print the hour, minute and second:
Serial.print("The UTC time is "); // UTC is the time at Greenwich Meridian (GMT)
Serial.print((epoch % 86400L) / 3600); // print the hour (86400 equals secs per day)
Serial.print(':');
if (((epoch % 3600) / 60) < 10) {
// In the first 10 minutes of each hour, we'll want a leading '0'
Serial.print('0');
}
Serial.print((epoch % 3600) / 60); // print the minute (3600 equals secs per minute)
Serial.print(':');
if ((epoch % 60) < 10) {
// In the first 10 seconds of each minute, we'll want a leading '0'
Serial.print('0');
}
Serial.println(epoch % 60); // print the second
}
// wait ten seconds before asking for the time again
delay(10000);
Ethernet.maintain();
}
// send an NTP request to the time server at the given address
void sendNTPpacket(const char * address) {
// set all bytes in the buffer to 0
memset(packetBuffer, 0, NTP_PACKET_SIZE);
// Initialize values needed to form NTP request
// (see URL above for details on the packets)
packetBuffer[0] = 0b11100011; // LI, Version, Mode
packetBuffer[1] = 0; // Stratum, or type of clock
packetBuffer[2] = 6; // Polling Interval
packetBuffer[3] = 0xEC; // Peer Clock Precision
// 8 bytes of zero for Root Delay & Root Dispersion
packetBuffer[12] = 49;
packetBuffer[13] = 0x4E;
packetBuffer[14] = 49;
packetBuffer[15] = 52;
// all NTP fields have been given values, now
// you can send a packet requesting a timestamp:
Udp.beginPacket(address, 123); // NTP requests are to port 123
Udp.write(packetBuffer, NTP_PACKET_SIZE);
Udp.endPacket();
}
For a complete list of examples, please check the ethernet library on github.