Opinions on Eagle and DesignSpark PCB : by Roger Lascelles. Tell me if I am wrong..

Farnell vs RS Components

In September 2009, Farnell bought CadSoft, the makers of the Eagle Schematic-PCB program. Farnell sells electronic components, and has been expanding worldwide. Farnell plans to build a parts procurement tool into Eagle. Farnell gives away a limited version of Eagle, but continues to sell the more capable versions. Farnell now call themselves “element14”, and present themselves as an engineering resource, rather than just a component supplier.

In July 2010, RS Components opened DesignSpark, a design portal and community for engineers, and offered “DesignSpark PCB”, a free, non-crippled and modified version of Easy-PC; a low end CAD tool from Number One Systems. RS also plan to build in a procurement tool.

Farnell and RS Components are the two big UK based players, and hope to make their engineering portals a haven for engineers who need inspiration, social contact and easy parts procurement.

Eagle has a monolithic component model, where each schematic symbol must use one of the PCB footprints that is stored in the same library file. This can lead to a proliferation of similar PCB footprints in different libraries, with different pin numbering or drawing style. The Eagle user interface defies normal GUI conventions. Eagle has a scripting language – fiendishly clever – but running scripts is the only way to achieve tasks which might be a simple menu item in another program. To learn Eagle, you will practice it, read the newsgroups and experiment until you are trained. Eagle is reliable and has a large community of users, including large companies. The free versions of Eagle are severely limited: unless your projects are small, you will need to pay money for Eagle.

DesignSparkPCB has three library types: Schematic, PCB and Component. A component links a schematic symbol and a PCB symbol. Because they are linked, you must keep the three types of library file correctly located and coordinated. Thus it is harder to share libraries with other people.

I have not succeeded in a netlist import using the offered “Orcad Schematic Netlist” format, probably because I've got the wrong file format. Netlist export correctly provides the PCB symbol name as the footprint value, but the file format is not popular. I don't see DesignSparkPCB as a general purpose schematic capture tool because it is tightly bound to the 3-library component system.

Other aspects of DesignSparkPCB are reasonable. The editors are OK to use. Remember to check your Gerber outputs with a viewer! At least RS will provide bug fixes.

Advance Circuits offers the PCB Artist derivative of Easy-PC, and has helpful documentation. In particular the Layout Software Part Creation Tutorial explains the library system.

DesignSparkPCB uses internet licence management, so if RS ever turns off the licence server, you can lose your investment in libraries and projects.

Finally

Most CAD tools link schematic symbol to footprint by a simple text field; giving you flexibility to use any combination of schematic and PCB tools. Eagle and DesignSpark PCB are different: they lock you in to a self-contained component model which keeps schematic and PCB inside the one program. That is a "we know best" approach, which gives the beginner an easy start, but ultimately limits you. Although both programs can produce VeeCAD compatible netlists, neither is friendly to VeeCAD or other tools. If you plan to evaluate Eagle or DesignSpark, be sure to check out other tools also. Don't be afraid to use separate schematic and PCB editors.