查看“Microduino ENC Network (2)”的源代码

{{Language | Microduino ENC网络（二）}}
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==Objective==
This tutorial will show you how to use a DHCP server to automatically configure network parameters.

==Equipment==
*'''[[Microduino-Core]]'''
*'''[[Microduino-FT232R]]'''
*'''[[Microduino-ENC28J60]]'''
*'''[[Microduino-RJ45]]'''
*Other equipment
**USB cable

==DHCP==
Usually, in local network you can find a DHCP server (Dynamic Host Configuration Protocol), that is a service which automatically configure the devices connected to the network.

Without explaining too deeply the protocol, it works this way:
The device (client) that needs an IP address, sends a DISCOVERY broadcast packet (that is a packet which will reach all the devices in the network), to “discover” if there are DHCP servers available;

If one or more DHCP servers are alive, they answer with an OFFER packet, “proposing” an available IP address to the requesting client;

The client chooses one of the offered IP addresses and sends a REQUEST packet, to ask for permission to use that address;

The server that proposed it, answers with an ACK packet to confirm the IP address association.

[[File:DHCPShow.jpg|600px|center|thumb]]

Luckly  what I described above has altready been implemented for us in the dhcp.cpp library file: I’m going to show a simple sketch using DHCP services.

==Schematic==
*Microduino-ENC28J60
*Microduino-RJ45
*Microduino-Core
*Microduino-FT232R

Stack all modules and then connect the ethernet cable, as follows:

[[File:MicroduinoENCShow.jpg|600px|center|thumb]]


==Program==
Download the program:
https://github.com/Microduino/Microduino_Tutorials/tree/master/Microduino_ENC/ENCnetworktwo

==Debug==

Step 1：Download the EtherCard library and copy to your libraries fold of IDE, then restart IDE.
https://github.com/jcw/ethercard

Step 2：Explain the program：

//First, I haven’t defined a fixed IP address anymore, just the MAC address. The controller’s initialization is still run with the usual begin() method.

ether.dhcpSetup();
//The dhcpSetup() method performs all the steps detailed above: looks for a DHCP server, check its replies, choose an IP address and ask for permission to use it. That method waits for 30 seconds, after that it returns an error.

ether.printIp();
//The printIp() method is an easy way to print on serial monitor an IP address (that is stored in Ethernet buffer as an array of uint8_t).


Step 3：Compile the code and download it.

Step 4：If everything goes right, you should be able to ping your Arduino again:

[[File:DHCPcmdPing.jpg|600px|center|thumb]]

==Result==

And our DHCP server will show a new device connected (EtherCard library chooses Arduino-XX as device name,with XX the last octet of MAC address):
==Video==

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