Guys, i'm now trying to draw the PCB for my Ethernet system.
It's just a simple single layer PCB. What's the simplest program out there you all would recommend that is easy to pick up and contains a good size component library?
While not in answer to yor PCB tools question, your post had something that caught my attention. From what I understand about implementing ethernet (I am no experert, but I am working on a project that will do just that) I am questioning whether or not a "simple single layer PCB" will be adequte electrically for ethernet. Have you investigated the electrical requiremnets regarding the transmission lines as they run on the board? Do they require a particular differential impedance, relative to the +/-, etc?
Note, a quick google search of the terms, PCB, ethernet, characteristic, and impedance pulled up a lot of application notes on interfacing to PHY devices which indicate that at a minimum a four layer board would be required and the transmission lines should be kept parallel, stubs should be avoided, and they should be designed for
50Ohm impedance. It also specified information regarding proper decoupling and protection.
He doesn't say which speed of Ethernet he's after, but assuming 10Mbps, I'll mention that I've seen such designs work fine on two layer boards. Unless the OP is going to start mass manufacturing his product and selling it, I doubt the effort and expense of a 4 layer PCB is justified.
Very basic and easy to use PCB Wizard 3, about $50.00.I tried a few free ones and found them to be way way more than I required. With PCB Wizard I was able to create the board in about 20 minutes. It's library had everything that I needed but again I am making boards with 10-25 parts on them.
Well, the reason i'm using Ethernet is because i'm sort of forced to. I'm using Belfuse's powerline module and this module use MII as its host interface
This is an academic project.
I understand building an Ethernet system involves alot of design parameters which with my current level of engineering knowledge might prove to be quite a challenge. Thus, i would really need any help i can get. This discussion group and you guys is one of them.
How about just a single layer? Assuming the size of the PCB is not limited?
Well, the reason i'm using Ethernet is because i'm sort of forced to. I'm using Belfuse's powerline module and this module use MII as its host interface
This is an academic project.
I understand building an Ethernet system involves alot of design parameters which with my current level of engineering knowledge might prove to be quite a challenge. Thus, i would really need any help i can get. This discussion group and you guys is one of them.
How about just single layer? Assuming the size of the PCB is not limited?
Now what i can only do is follow the reference design and fabricate the PCB (since testing on a breadboard is not possible) and cross my fingers.
Search for express pcb. easy to use and can print double layer designs. Jim.
More on this "package":
(ExpressPCB is a fab house; software is NOT what they do)
Ant_Magma wrote:
Do you mean that this is for school? If so, I think you may have bitten off more than most students can chew.
If you are carefull, can read and comprehend reference desings and datasheets, and have sufficient proficieny with your PCB tools you may be able to handle it.
As one of the previous posters said, they have seen lower bandwidth ethernet implemented on less than four layers, though I wouldn't be inclined to try it. There are a couple of problems with boards less than four layers. First, the addition of a power and ground plane provide a natural source of bypass capacitance to your power system. Typically, though this capacitance doesn't come into play until you hit fairly high frequencies. What this means is that a lot of applications you can get away with a two layer board. The second problem is that in order to have a stable power supply system you need to have a low impedance ground path. Note the word impedance as this also includes inductance. To get a low impedance path you need to have a solid ground plane. Even a plane full of holes is infinitely better than serpentine traces. On a two layer board you can implement a copper pour as a ground plane. If you are using PTH components, you should consider putting the pour on the top so that you don't warp the board with a wave solder. Thid, you need to be judicious in your use of bypass capacitors. You are best off with a low inductance package such as a chip components as opposed to through hole. They need to be close to the power pins (less than .25") and need to be of a proper type. Aluminum Electrolytics are ghastly in this type of application. Ceramic are a much better choice, with .1 to .01 being typical values per rule of thumb.
Implemented properly you can meet the requirements of having a stable power reference (low impedance power and ground over the freq band of interest), even on a two layer board. A single sided, single layer board can't.
The other problem you may run into with ethernet is that the data lines requie a certain characteristic impedance and are matched in impedance. This means you need to be carefull in your layout to keep the traces the same length. The characteristic impedance, is determined by geometry; trace width, thickness, and distance from reference (plane). Without a reference (ground) plane you can't get a deterministic impedance as you will have no idea where the high freq return currents will flow (it may not be along the copper).
There will be some finger crossing involved. If you are confident that you have done everything to the best of your ability, followed proper guidelines, etc there shouldn't be too much risk. Like I said though, trying to do this on a single layer board, I doubt if it will work. Two layer, single sided your chances go up. Four or six layer board, per recommendations of the IC manufacturers you start getting pretty good odds.
hmm, that jim thompson is not me. but the subject was "simple pcb program" and it is simple and free. I have used it to draw up 2 layer boards, print each layer out, scan into photoshop to edit slightly , and print to toner transfer paper to make my pcb's. So it will do "simple" boards. What I would like to find is a pen plotter with flatbed and load it with laqcuer ink to draw on the copper clad directly.. Know of any cheap plotters out there?
Jim..
On 9 Mar 2006 07:24:43 -0800 in sci.electronics.basics, "Ant_Magma" wrote,
PCB design software is in the CAD (computer aided design) category, so this question should be on sci.electronics.cad When you get there look for Terry Pinnell's encyclopedic review of what's available.
Never get your PCB software from the company that wants to sell you boards. It's a scam to get you to design the board using their "free" software... then when you are done you find out that they are the only place that will make boards for you. Get your software from a software company so you can shop around for the boards.
I like Eagle from
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