Modifying existing board designs

David B

I want to make my own PCB board for the propeller. Well, I don't really want to, but none of the existing boards are quite what I want to work with.

Specifically, I've found more and more over the years that subminiature "D" connectors are more convenient than any other connector for temporarily attaching accessories to a development board; 25 pin for an 8 bit data bus, a few control lines, power and ground, and 9 pin for connecting serial devices with power and ground.

I'd like a Propeller development board with several built-in "D" connectors: one 25 pin "D" and 3 or 4 9 pin "D"s, plus an EEPROM and programming interface. And maybe a built-in two-line LCD, as that also has become a standard accessory in the boards I've used.

As a PCB newbie I've never taken the time to get started at a full PCB board design, and was wondering if it would make sense to start with an existing design and modify it, sort of like how programming code is developed. I've never tried this - is it possible, and would it make sense?

I see lots of ExpressPCB artwork at http://www.rayslogic.com/propeller/PropPCB/PCB_Boards.htm:

PropDip_V11.zip······························ Ray Allen
Miniprop_I.zip······························· Ken Peterson
PropDipEkg11.zip····························· Ray Allen
Propeller_Express_Rev_F.zip·················· Newzed
Propeller_Platform.zip······················· Jon Williams
Propeller Multi-Controller Board.zip········· Chris Savage

Are any of these available for people to copy and modify? I've looked in each zip and haven't seen any license or copyright or sharing information. But I think that copyrights are implicit in works of art, is that right? So would each person need to individually release his or her work for public use, if they chose to do so?

This is just a hobby for me. If I were to make this design, I'd make it available to anyone.
·

Toby Seckshund

If it were just for personal use, and stayed that way, then as the info has been offered up then I would use it.

My first playings with the Prop was with a homemade copy of the DemoBoard. I am trying to remember the name of the AVR system that uses 9 way "D" type interconects like lego bricks.

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Dr_Acula

No board ever does quite what you want *grin*.

I like D9s too. Especially since futurlec sell them for about 50c.

I took some existing designs and modified them (the prop demo board, the pocketerm, cluso's triblade). Design now has a LCD display, vga, keyboard, ram and sd card. You can add or remove bits as required for your design as it is all open source www.smarthome.viviti.com/propeller

Toby has already made several homemade boards based on this design and I think has been experimenting with adding bits and leaving bits out.

If you check out the text of that link, buried near the bottom is a link to the source files for Eagle. I'm up to version 4 for getting physical boards made. Before getting a new design made, it probably is worth getting a breadboard and testing it out.

It is great fun drawing up schematics and turning them into PCBs - a steep learning curve but well worth the time.

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www.smarthome.viviti.com/propeller

JonnyMac

The files I upload to Nuts & Volts (e.g., Propeller Platform) usually have a little text file that says you are free to do with the files whatever you want -- just don't ask me for help modifying them! So... if you want to take the Propeller Platform files and bash 'em up to your liking, you have my blessing (and I expect you'll get it from the others).

Just a hint: if you're going to use ExpressPCB, start with the schematic and get it nailed down. Once you do, link your [noparse][[/noparse]new] board to the schematic so that the PCB layout software what connects to what. It helps.

JonnyMac
The Artist Formerly Known as Jon Williams

WBA Consulting

I think you really need to decide what your main need is. Designing your own PCB could end up being long and tedious, but will be very rewarding and give you exactly what you want. It may not be the most cost effective way, but having YOUR ideal design at your fingertips may be the most beneficial in the long run. I am working on a design currently for the Propeller Design Contest that in a way is similar to the Parallax Protoboard and/or Propeller Platform designs, but has 2 key features I want in a low-cost prototyping board that is not currently available with any layout. Those 2 features are why I am designing my own. All my other projects using the propeller have been "tweaked" to make use of an existing design (protoboards, propstickUSB, and mctrivia's propmodule 1x1).

If you just want DB connectors available to you, have you looked at breakout boards like SparkFun's DB9 Breakout board?

Or, to make it really easy for a design, just make a DB9/DB9/SDB25 PCB that mates onto a protoboard or propeller platform board? Lots of stacking ideas out there.

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Andrew Williams
WBA Consulting
WBA-TH1M Sensirion SHT11 Module
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CannibalRobotics

I'm an ExpressPCB fan. As for design, I 'borrow' allot of·concepts from other boards but at the end of the day,·I like to design my own. I know how it works, why the stuff is there and how it's expected to perform. You can get into trouble coping/borrowing PCB design artwork pretty quick and never know how you got there.

To help in your quest I've attached a Prop_44 pin custom component for your ExpressPCB library.

Good Luck!

Jim-

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Send $1 to CannibalRobotics.com.

David B

Thanks for the help, everyone.

In fact, I did make an adapter for a spinStudio board that presents a DB25, and I've got a 512K static RAM board plugged into the DB25 connector, and it works pretty well.

What I'm looking for is really just a nicer-looking version of that same design.

Nick McClick

No stated license = All rights reserved. Jon has graciously put the The Propeller Platform in the public domain, the newest revision expresspcb layout & schematic are up on the project page. For the other designs, you should probably shoot an pm to the designer to make sure it's okay. I doubt anyone would mind, but it's better to be on the up-and-up.

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Leon

I make my own PCBs at home, and have designed and made a few Propeller boards with exactly the features I need, in a couple of hours. Here is one example:

www.leonheller.com/Propeller/XProp/XProp_photo.gif

Leon

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Post Edited (Leon) : 1/6/2010 1:11:17 PM GMT

Toby Seckshund

If you are thinking about learning a PCB design program, try to get into the one you intend to stay with. I use FreePCB because it was just that, in comparison to heavier weight progs it was easier to start with but now I want better libraries ansd schematic capture I have to learn it all over again, with the old habits to get in the way.

I layout with FreePCB, print via Viewmate onto a HP laser and etch with Ferric Chloride. Single or double sided is possible but great care is needed for SM small pitch stuff. With a better buget the layouts would be handed over to commercial PCB mfrs and the glorious through hole plating would be done.

With ones or twos homemade is good, for 10s and 20s not so.

Leon What material is your PCB ?

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David B

I'd consider making my own board if I could make one as nice as Leon's.

Leon, what was the process you used to make that board?

I've made quite a few boards many years ago by hand-drawing circuits with sharpy markers, then using Radio Shack etch. They usually worked ok but looked bad, and broken or shorted traces were not unusual. (I used to vaporize hair-thin shorts between traces by charging up a capacitor, then discharging it across the shorted traces.)

That was fun, but at this point I'd really only want a decent quality board.