Arduino Ethernet W5100 minimal circuit

Hi, I am using Arduino with 8MHz internal crystal. I do not need any other electronic parts, only ATmega and power supply (7805). There is working schematic: http://todbot.com/blog/wp-content/uploads/2009/05/minimal-arduino.png
I have about 5 working cirtucits based on this schematic that works more than one year without error.

Now I need add Ethernet. I would like to buy officialy supported Wiznet W5100. (For testing I was bought original shield.) Can you please help me how can I connect W5100 to ATmega328 with minimal other parts? I was looking into official Arduino Ethernet Shield schematic, but it is big complicated to me: http://arduino.cc/en/uploads/Main/arduino-ethernet-shield-06-schematic.pdf

I do not need SD card reader or any other device. Only Ethernet.

Is it neccesarry to use H1012NL transformer (or similar) and connect RJ45 socket to W5100 through this transformer? Is it possible to buy RJ45 socket with integrated protection? Or how it works on original shield?

I can't use original shield because is to big and I need small and manufacturable board. If it is important I can put 16MHz external crystal to ATmega.

I found a lot of minimal schematics for ENC28J60 but not for W5100 :frowning:

Thanks for help.

martin159:
Can you please help me how can I connect W5100 to ATmega328 with minimal other parts? I was looking into official Arduino Ethernet Shield schematic, but it is big complicated to me: http://arduino.cc/en/uploads/Main/arduino-ethernet-shield-06-schematic.pdf

Well, that's pretty much how it's done. Compare that to what's in the W5100 datasheet. I've also used the WIZ811MJ and WIZ820io (W5200) modules. Unless we're talking considerable volume, those modules may represent a better choice. If you are really bent on rolling your own, then it sounds like you will have a learning curve.

WIZ820io looks good but it is too expensive (about $25). But I found schematic on web. Thank you :slight_smile:

If I use RJ45 socket with integrated transfromer, It looks simply: http://www.wiznet.co.kr/Admin_Root/UpLoad_Files/BoardFiles/WIZ820io_Schematic_V1.0.pdf
http://www.wiznet.co.kr/Admin_Root/UpLoad_Files/BoardFiles/WIZ820IO%20Rev1.0%20Partlist.pdf

This is all deja-vu to me. I have the Ethernet shield, I have a few of the WIZ modules, and I'm sourcing parts to begin a home-brewed W5100 design. Yes, you'll need integrated magnetics. One of the Pulse MagJack connectors will work. Get one for 10/100 with auto-MDIX support. (This ensures the xformer etc. are all symmetric so the RX pins work as TX and vice versa.)