WIZnet Developer Forum

Novice question: how to connect to DHCP, send simple message

I made a prototype board with a W5500 and Atmel ATmega32U4 (connected via SPI). I’d like to set up a simple program to upload to the microcontroller to have the W5500 negotiate with a DHCP server to get an IP address, then send simple commands (HTTP requests to a fixed server).

I don’t really know where to start. I downloaded the Wiznet ioLibrary but it seems to be geared more towards setting up a DHCP server on the W5500 (unless I am mistaken). What I’d really like is a very simple example program showing how to connect to DHCP and send simple messages. Does such a thing exist?

Thanks very much.

Look at the W5100 home page; somewhere at the bottow you will see:

W5100 Application Note

How to implement DNS
How to implement DHCP
How to use Multi-casting
How to use ADSL (PPPoE)

Download that file, and study DHCP application note. If you talk about how to send UDP messages using W5500, these matters are well covered in the W5500 datasheet and W5100 datahseet (yes, please refer to W5100 datasheet for explanation how to set up TCP/UDP/IP stack for W5x00 family).

Further, you go to Wikipedia and search internet to read some more information about DHCP. DHCP is a protocol, and is not actual issue of W5500; the chip is just a way to send and receive specific messages (in your case - DHCP).

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Hi Eugeny, thanks a lot for the information. I’ve taken a look at the application note and it looks useful - I’ll try out the example and see how I get on.

I understand from your post that the W5100 datasheet covers UDP and TCP, whereas the W5500 covers only UDP? Is that correct?

Cheers again!

No, W5500 datasheet is full of useful info about the W5500 chip, but basics of the processes setting up the chip family can only be found in W5100 datasheet pages 29 (status register flow diagram) and in chapter 5 “Functional descprion”.

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