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Week 4 page

Eagle

Eagle is a CAD software used to design circuit schematics and board layouts. It's available as a freeware through their website. The free version is limited to 2 layered board designs.

Two other useful downloads are The Sparkfun component Library and the PCB G-Code. You can add the Sparkfun Library by dropping the file into /EAGLE-6.4.0/lbr. And the PCB Gcode into /EAGLE-6.4.0/ulp


Schematic & Board Design

As a starting point I downloaded David Mellis' Schematic (fabisp.sch) and Board (fabisp.brd) files from the link in Neil's Lecture page Link

Once you have either of the files open, it will automatically open the other. You can switch between the schematic and the board views with this symbol .

Starting a new project would be done on the schematics page by selecting the correct components from the library, placing them in an appropriate loacation and joining the correct wiries. The schematic can then be used to create the circuit board. This process will be attempted in the following weeks, once a greater understanding of circuit design has come to me.


As a begginners exercise I tried to alter the overall shape of the board and relocate the USB traces. In order to do this I had to take the following steps

  • Group all Components
  • Move grouped >>control+right click
  • Select 'dimension' layer
  • Select line tool and sketch desired new outline
  • Move tool > move usb trace
  • 'rip-up traces connecting to usb
  • Use autotracer to re-route the traces
  • I also replaced the text with my own label

    • The outcome:

    You can see that I extended 2 of the traces from the usb inwards to make soldering easier


    The exported image:


    Exporting the Code

    PCB Gcode Eagle add-on

  • After adding the pcb gcode to the ulp file you need to set up the directory so that it will find the software when you try to run it. To do this you need to open eagle>options>directories> and under 'User Language Programs' add the loacation. For me I had to add ':/Applications/EAGLE-6.4.0/ulp/pcb-gcode' so it then looked like:

  • With the finished board page open write the command 'run pcb-gcode-setup'. You can now choose the required parameters for cutting your board and generate your gcode



    • FabModules

  • In Eagle select the layers you require for cutting
  • File>Export>image
  • Select a high resolution image such as 600dpi to ensure good quality; monochrome
  • run fabmodules - png to gcode - load image - select parameters - generate g code