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Building an ENC28J60 Ethernet Dev Board
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Date: 2006/03/13 16:48
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By: Ian
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Status: Moderator
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Karma: 5
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| Posts: 85 |   |
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This thread discusses the Content article: Building an ENC28J60 Ethernet Dev Board
Hope you find this article useful and I haven't put in too many errors. If you have any questions feel free to ask them below.
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Re:Building an ENC28J60 Ethernet Dev Board
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Date: 2006/03/13 16:51
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By: Mat
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Status: Admin
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Karma: 7
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| Posts: 211 | |
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Thanks Ian  A Fantastic start!!! Very informative and should be easy to follow for anyone wishing to start developing an ethernet based device. 
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ENC28J60
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Date: 2006/03/13 16:54
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By: asmallri
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Status: User
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Karma: 2
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| Posts: 5 | |
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A good first article. I have a few comments to the schematic.
- R1 should be increased to 2.7K as per the current ENC28J60 errata.
- C10 is missing the connection to ground.
- The 25MHz crystal for the ENC28J60 could also be used to clock the PIC. Assuming the crystal is connected to the ENC28J60 then connect OSC2 of the ENC28J60 to the OSC1 of the PIC
- The ENC28J60 is very power hungry, the regulator needs to be a TO220 or, if SMD, a DPAK size package.
- I use a RJ45 with embedded magnetics (such as the YCL PTC1111-01) instead of a separate isolation transformer. This enables a smaller PCB footprint. There are alternatives with embedded LEDs for an even smaller footprint.
- For a general purpose test board I would propose adding a SD card connector as the interface to the PIC is trivial.
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Re:ENC28J60
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Date: 2006/03/13 16:54
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By: Ian
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Status: Moderator
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Karma: 5
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| Posts: 85 | |
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Thanks for the comments.
My errata document was out of date. I have updated the schematic and the article taking into account the new errata document.
I like the idea of using the one crystal to drive both the PIC and ENC. I had thought of using the clock out from the ENC, but avoided it for now because of the issues if you put the PIC to sleep and to make the board easier to debug.
For my final board I also intend to use a RJ45 with integrate magnetics and LEDs. I just used the parts that came to hand for this version.
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One more change to the stack...
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Date: 2006/03/13 16:55
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By: cledic
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Status: User
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Karma: 2
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| Posts: 7 | |
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Thanks Ian; very good article.
I find, from a magazine, a software modification to the stack that works for me.
To improve Stack stability the article suggest to modify the SPI freq, changing the SSPCON1 reg. value from 0x20 to 0x21 for a clock of 20MHz.
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Dynamic IP Address
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Date: 2006/03/13 16:55
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By: amane
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Status: Visitor
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Karma: 0
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| Posts: 0 | |
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Hi Ian,
How did you get the IP Address assigned to the ENC by the DHCP Server? I'm new to this so I don't know much about networking protocols. Thanks..
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DHCP
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Date: 2006/03/13 16:56
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By: Ian
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Status: Moderator
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Karma: 5
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| Posts: 85 | |
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When the ENC boots up it sends a BOOTP broadcast packet to find DHCP servers on the network. Then when it finds one it requests an IP address.
I have a DHCP server running on my PC which is connected directly the ENC. You can watch this exchange using a packet monitor such as ethereal.
The microchip stack includes a program called MCHPDetect which listens for annoucements from PICs when they get an IP address
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Re:Building an ENC28J60 Ethernet Dev Board
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Date: 2006/03/13 16:56
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By: bily
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Status: Visitor
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Hi Matt,
Your site is wonderful, I am going to try it. Can
you explain why you added 16PT8515 ?
Thanks.
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Wasn't me...
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Date: 2006/03/13 16:57
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By: mat
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Status: Visitor
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Hey, Sorry for the confusion, I editted the page today, Ian originally wrote this article (as anyone can upload them!!), in editing it I forgot to set the author back to him  ! All being well he should be able to answer your question better than I can. So i'll leave it to him!!
Mat
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16PT8515
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Date: 2006/03/13 17:00
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By: bily
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Status: Visitor
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Ok, it's the transformers in a package.
I can't find a dealer for it, i'll get the transformers
from maplin.co.uk- about 2 pounds each
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Re:16PT8515
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Date: 2006/03/13 17:01
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By: Ian
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Status: Moderator
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Karma: 5
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| Posts: 85 | |
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You guessed correctly, the 16PT8515 is a magnetics chip with the transformers in. I used that one because it was on an old network card I had kicking round. Which transformers are you using (from maplins) would be useful to get a list of ones that work.
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