PCB Design Tools and CAD File Formats
Adrien Grise
The object of this lab was to utilize EagleCad to develop a schematic and board diagrams for our latest bus-ized lab project. From there, various conversion routines and applications would be utilized to eventually generate CAMM-I commands for the Roland EGX-300 that resides in the Robotics Lab. However, since Roland Signmate (the official software supporting the EGX-300) is not part of the Robotics Lab resources, a conversion utility must be developed.
The project has 2 parts:
PCB Design and Gerber Generation
After installing the EagleCad Freeware system on my PC, I began to develop a schematic diagram of my lab project. The LogoChip was found under PIC16*876P and I’ll note that the ‘*’ character is important because a search of “PIC16876P” yielded nothing initially and caused some minor confusion. Next I dropped down an oscillator for the clock connections of the LogoChip. Finally, I needed a 5x7 LED display. Since no such LED display existed, I edited the hp-display.lbr library and created a new device to represent the 5x7 LED display that was utilized in our lab project. This involved making use of the helpful design document found at Eagle’s website.
I did not add the bootflash circuitry to simplify the schematic. At a later date, after all issues are ironed out, I can go back and add these devices in if necessary.
Next I made wire connections from the various pins of each device. I then created a board diagram from this schematic, routing the wires and moving the devices around the limited workspace made available by the freeware version of EagleCAD.
I then followed the instructions on generating Gerber Output files that was given with this assignment and previewed the diagram that was generated by these files.
I took the generated files and with the use of C. Scott’s PCBMill Web Utilities site attempted to generate HPGL (Hewlett Packard Graphics Language) plt files. However, I was unsuccessful as after submitting the files, an error page was returned indicating that some improper characters where read in one of the files. At this point, I’m unsure why the system is failing in the manner it is.
Eventually, I hope to build these plt files. From these plt files, a conversion utility should be fairly straightforward to write. It would involve a detailed understanding of the format used in the plt file (available at HP’s web-site) and a description of the CAMM-I commands used by Roland Signmate. A simple compiler utility could be written to parse each line in the plt file, determine the command and its parameters and converting that into equivalent CAMM-I files. Since I was unable to generate the base plt files however, I cannot attempt to develop any such code at this time.