ETHERNET COMMUNICATION with ENC28J60

  Hi friends.I haven't broadcasted my blog for a long time.I am here with one of the performed projects in this time period.We will provide Ethernet communication in our project via SPI (Serial Peripheral Interface)  with ENC28J60 ethernet chip. SPI is one of serial communication protocols which allowing data exchange with peripheral units or microcontrollers.The ENC28J60 ethernet chip provides  data communication with microcontroller via SPI,up to 10 Mbit / s speed.

   Block diagram of our project;

   Pin configuration of our ENC28J60 Ethernet chip is as below.

   SPI is full duplex and synchronous serial communication protocol.Data transfer is performed by the master-slave relationship in SPI communication.

    SPI protocol is run with four signal line.

  *SI  (SDI)  :Serial Data In,                                                                          

  *SO(SDO):Serial Data Out,                                                                                 *SCK:Serial clock signal,

  *CS:Chip Select.If more than one slave device exists , cs pin of related device is activated to communicate with which device.

  You can set up a circuit as follows for ethernet communication.

    You can use the microcontroller you want at your circuit  but provided  that, SPI and more than memory of 4 KB exists.We need pay attention to matter "crystal of  microcontroller must be  8-10 MHz". I used 16F877A microcontroller  with 10 MHz crystal but I used ready-made module, ınstead of communication circuit.

   

   Now let's specify , what we will control and how we will write a program with ethernet communication. We will do LED and LCD control With ENC28J60 module. We will do an interface UDP terminal  with Microsoft Visual C #. We will send our packages buffer of enc28j60 via ethernet socket with the UDP terminal.  Microcontrollers will receive data from the buffer.If microcontroller received package , which our specified (If the "LED ON" button  pressed),  we will burn led and we will print "LED ON" on the LCD screen.If the microcontroller received package , which  our specified other (If the "LED OFF" button  pressed), we will extinguish led and we will print "LED OFF" on the LCD screen.

   Ethernet communication is taken place via sockets.Sockets  creates our network. Socket specifies two basic address information of the our network. These  IP address and port number.We will specify IP address and port number in our program .

   There are two types of  sockets which used in Ethernet communication.These UDP(User Datagram Protocol)  and TCP(Transmission Control Protocol) . We a little talk about essential differences between TCP and UDP.

* TCP is slower than UDP. Because, the data  sends in a sequential manner and the data is checked whether it reached other side.Due to these reasons, it is safer than UDP.

*UDP , veriler sıralı bir şekilde olmayıp bağımsız bir şekilde karşıya gönderilir. Therefore, it is  faster according to TCP. Because to be fast, UDP is used  to send the video and audio .                                                                                                    

   Now,we can give  our project's general circuit .

   We wrote  our program in mikroC PRO for PIC compiler. Because, many libraries are  ready in mikroC and can be used easily .Our program is immediately below.

/////////

#define SPI_Ethernet_HALFDUPLEX     0
#define SPI_Ethernet_FULLDUPLEX     1

//************  SPI protocol connections *****************
sfr sbit SPI_Ethernet_Rst at RC0_bit;     
sfr sbit SPI_Ethernet_CS  at RC1_bit;
sfr sbit SPI_Ethernet_Rst_Direction at TRISC0_bit;
sfr sbit SPI_Ethernet_CS_Direction  at TRISC1_bit;

//************  LCD module connections  ******************
sbit LCD_RS at RB4_bit;
sbit LCD_EN at RB5_bit;
sbit LCD_D4 at RB0_bit;
sbit LCD_D5 at RB1_bit;
sbit LCD_D6 at RB2_bit;
sbit LCD_D7 at RB3_bit;

sbit LCD_RS_Direction at TRISB4_bit;
sbit LCD_EN_Direction at TRISB5_bit;
sbit LCD_D4_Direction at TRISB0_bit;
sbit LCD_D5_Direction at TRISB1_bit;
sbit LCD_D6_Direction at TRISB2_bit;
sbit LCD_D7_Direction at TRISB3_bit;

//****************************************************
typedef struct {
  unsigned canCloseTCP: 1;  
  unsigned isBroadcast: 1; 
} TEthPktFlags;

char txt[17], template_msg[] = "UDP msg rcved:", error_msg[] = "msg too long!";
   
//*******************************************
unsigned int SPI_Ethernet_UserTCP(unsigned char *remoteHost, unsigned int remotePort,unsigned int localPort, unsigned int reqLength, TEthPktFlags *flags) {
  return 0;             
}
//********************************************

unsigned int SPI_Ethernet_UserUDP(unsigned char *remoteHost, unsigned int remotePort,unsigned int destPort, unsigned int reqLength, TEthPktFlags *flags) {
  unsigned char len = 0;

  if (destPort != 10001) { //if the destination port is not 10001
    return 0;              //there will be no reply                 
  }
  
  if (reqLength > 16) { 
    Lcd_Out(2,1,error_msg);            
    return sizeof(error_msg)-1;
  }
  
  Lcd_Cmd(_LCD_CLEAR);                      // clear Lcd.
  Lcd_Out(1, 2, template_msg);              // display template message.

 while(reqLength--) {
    txt[len++] = SPI_Ethernet_getByte(); 
  }

  txt[len] = 0;
    if(!strcmp(txt,"g"))                    //compare txt and "g".
    {
     Lcd_Out(2, 1,"LED ON");
     PORTD=0x01;
    }
    if(!strcmp(txt,"s"))                   //compare txt and "s".
    {
     Lcd_Out(2, 1,"LED OFF");
     PORTD.f0=0x00;
    }
     
  return 0;
}

//***********************************

unsigned char myMacAddr[6] = {0x00, 0x14, 0xA5, 0x76, 0x19, 0x3f};   
unsigned char myIpAddr[4] = {192, 168, 2, 1};                      


void main() {

  TRISD = 0x00;
  PORTB=0;

  Lcd_Init();                               // initialize Lcd.
  Lcd_Cmd(_LCD_CLEAR);                      // clear Lcd.
  Lcd_Cmd(_LCD_CURSOR_OFF);                 // turn off cursor.
  LCD_Out(1, 2, template_msg);              // display template message

  SPI1_Init();
  SPI_Ethernet_Init(myMacAddr, myIpAddr, SPI_Ethernet_FULLDUPLEX);

  while(1) {                  // endless loop              

    SPI_Ethernet_doPacket();  //process incoming Ethernet packets              

  }
}

////////

   Specify the task of few functions in our program.

   SPIx_Init();                                                                                                            This function  installs SPI protocol with standard settings  and its operation starts.If you want to use custom settings instead of the standard settings,you can use the Spıx_ınit_advenced ( )  function. 

  SPI_Ethernet_Init();                                                                                         

 This function installs ethernet library over SPI protocol and its operation starts.
Sample usage:  SPI_Ethernet_Init(myMacAddr, myIpAddr, SPI_Ethernet_ FULLDUPLEX); .We provide full-duplex operation of the ENC28J60 module which specified MAC and IP addresses in this example.

  SPI_Ethernet_doPacket();                                                                                  This function initializes operation of UDP and TCP.I mean, it calls and runs SPI_Ethernet_UserTCP();  and  SPI_Ethernet _ UserUDP();  .

  SPI_Ethernet_getByte();                                                                                      It reads 1 byte data from enc28c60 buffer.

  SPI_Ethernet_putString();

This function puts string or character array in buffer of Enc28c60 .

   After you specify them, we can analyse terminal which  made  the Microsoft Visual C# . Our terminal will have four buttons. Two of buttons to open-close the socket and other two to blink our led.Picture below is better understood.

   

  You can find C # program below .

////////

using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Linq;
using System.Text;
using System.Windows.Forms;
using System.Net;
using System.Net.Sockets;


namespace ethertnet2
{
    public partial class Form1 : Form
    {

        // string Ip = "192.168.2.1";
         //int port = 10001;



        IPEndPoint ipepC;
        Socket udpclnt;     //newsock
         byte[] byteSend;
         int intRcv;
         bool epSFlag = false;
         bool displayRcvFlag = false;
         string stringRcv = "";


         public Form1()
         {
             InitializeComponent();
         }

         private void button1_Click(object sender, EventArgs e)
         {
           IPAddress serverAddr = IPAddress.Parse("192.168.2.1");
           ipepC = new IPEndPoint(serverAddr, 10001);
           udpclnt = new Socket(AddressFamily.InterNetwork, SocketType.Dgram,ProtocolType.Udp);
         }

         private void button2_Click(object sender, EventArgs e)
         {
           udpclnt.Close();
         }

         private void button3_Click(object sender, EventArgs e)
         {
           byteSend = new byte[5];
           byteSend[0] = 103;
           udpclnt.SendTo(byteSend, ipepC);
        
         }

         private void button4_Click(object sender, EventArgs e)
         {
           byteSend = new byte[5];
           byteSend[0] = 115;
           udpclnt.SendTo(byteSend, ipepC);
         }

     }
 }

////////

   Explain briefly our program.We should import  System.Net and System.Net.Socket in the program to do ethernet communication.

 using System.Net; 

 using System.Net.Sockets;

   Our IP address is specified as "192.168.2.1"  and port number is specified as 10001 when  "SOCKET ON" button is clicked that first button.Then,with udpclnt = new Socket (Address Family.Inter Network,SocketType.Dgram,    ProtocolType.Udp);  , a new instance of the Socket class is opened by the name of udpclnt and the type of UDP.

   Our UDP socket connection is closed with udpclnt.Close();  when "SOCKET OFF" button is clicked that second button.

   We opened location of five bytes in our array which we defined bytesend name when "LED ON" button is clicked that third button with byteSend = new byte[5]; . We assigned  as 103 to first element of the bytesend array.The 103 is 'g' character's decimal equivalent. Then ,with udpclnt.SendTo(byteSend,ipepC); we sent  'g' character our port . Thus, we have sent  'g' character to the buffer of Enc28j60.

   When "LED OFF" button is clicked that is fourth button does similar operations what third button does.The differance that 115 is assigned to first element of bytesend array. The 115 is 's' character's decimal equivalent.

After we specify them now we can connect to computer our circuit with an ethernet cable. But probably,you will see warning of "Unidentified Network" in your local network. As shown in the picture below from the Local Area Connection Properties , you must write a different IP from the IP address that you specify in the program to  identify network in IP address box the TCP / IPv4 option by double-clicking from TCP / IPv4 properties.As for the default gateway box,you must write IP address that you specify in the program. After making these changes, your network will be defined.

    After network identified, on the ENC28J60 module, yellow led which is nearby RJ45(with transformator) must be lighting and yellow led must blink.Now ,we can open and run the terminal which did with C#. Also Udp Terminal is located in the tools menu of MikroC PRO for PIC compiler , you can use it.

      See you next project.I wish you success.Sincerely.