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Wednesday, 4 June 2014

PCB design - Eagle and Fritzing

Yesterday I got involved in a couple of discussions on Twitter on two related topics: choosing software for PCB design, and choosing PCB Fab companies to make short runs of prototype boards.

I'll write a little about the PCB Fabs in another post. At the risk of having to don flame-proof safety gear, I'll share some of my experience from the last couple of years, and my current preferences.

Quick2Wire Analogue Board

Disclaimer

Please don't expect an exhaustive survey. I don't normally work on Windows, and I don't have a Mac, so this is written from the perspective of a Linux user. That's why I have not tried DesignSPark PCB. Nor have I looked much at KiCad, simply because my first attempts some while ago were discouraging.

Eagle and Fritzing

The two products that I have used are Eagle and Fritzing.

Eagle is very well established as a design tool for amateur and professional users. It's very capable, and has very extensive libraries. Since CADSoft ( the authors) were acquired by Premier Farnell, it has good integration with the Farnell website. Some PCB Fab shops accept Eagle .brd files directly for manufacture, and almost all will accept the gerber files which Eagle can export.

When we started Quick2Wire we decided to use Eagle for all our PCB designs. Two of the team had good Eagle skills, and I was somewhere between novice and competent.

Quick2Wire MCP23017 board
Sadly, one of the Eagle experts was a temporary team member: he'd warned us at the outset that he was involved with a couple of other start-up projects which would eventually have to take priority. (He's gone on to create the very successful Nova).

Even more sadly, the other expert became seriously ill after he'd completed the layouts of our first three boards, and was unable to carry on with the project.

My own expertise was limited, and there were too many other calls on my time for me to ramp up my skill level.

The Eagle learning curve

Another member of the team decided to have a go, and spent several weeks trying to get to grips with Eagle. He's a very bright guy, and his degree was in Electronic Engineering, but he still found Eagle hard to use. His experience mirrored mine when I first encountered the product, and we're not the only ones who have found the Eagle interface hard to master.

Some while before Quick2Wire started I'd come across another software tool called Fritzing. It's open-source software that you can use to capture a breadboard layout. Once you've done so, you can edit the corresponding schematic and go on to produce a PCB design.

Illustrating projects with Fritzing

When I first met it, Fritzing had great potential for illustrating educational material but reports suggested it was a little immature as a PCB deign tool. We made considerable use of its breadboard view but never experimented with the board design capabilities.

With hindsight that was a mistake. When I started work on the lobstar I decided to use Frizting for the PCB design. I made a couple of mistakes before I got the design right, but that's par for the course: Quick2Wire had three runs at each of our boards.

Fritzing for manufacture

Fritzing has been intuitive to use and has generated the files required by the three companies I used to make lobstar prototypes.

I'll tell you who those companies are in a later post, and show you the results.