ECAD SCHEMATIC CAPTURE. Fred Heep/George Austin SFU Engineering Science June 2000

Transcription

1 ECAD SCHEMATIC CAPTURE Fred Heep/George Austin SFU Engineering Science June 2000

2 What is ECAD? Electronic Computer Aided Design Typical uses may include Schematic Capture PWB Design Simulation/Analysis Product Production Documentation

3 EDA TOOLS Electronic Design Automation Complete design Software Schematic entry Mixed-signal simulation PLD design PWB layout with Autorouting Signal intregrity simulation 3D PWB viewing Integrated document management

4 ECAD Benefits Neat, professional drawings Easy coordination of multiple sheet drawings (hierarchical) Changes to all aspects of a project can be easily updated (with quality up-to-date software) Easy to get data, production docs/files out Forward & back annotation keep schematics and PWB designs in sync; helps to avoid errors.

5 ECAD Benefits - cont d Electrical & mechanical design rule parameters (PWB placement & routing) are quickly checked More easily linked to ATE & production machine processes With some classier products, engineers can add notes and formulas to nets. Very useful for PWB designers and production floor assembly/calibration/testing.

6 ECAD Shortcomings Expensive ($300-60K USD) Challenging to get data in Can be significantly slower than hand drawing until proficient (software package dependent) Simple tasks can be very frustrating & gross time-wasters to accomplish until expertise is developed with the software Often steep learning curve

7 ECAD Shortcomings - cont d Computers give false sense of security that calculations, placement, routing, etc. are done correctly Can be challenging to share info with others who do not have the same software package. Takes discipline to maintain accurate software file management for revision levels and backups Software formats change rapidly and long term compatibility with even the same brand of software is generally not possible.

8 ECAD Shortcomings - cont d Compatibility between software packages is virtually non-existent and there are no industry standards. Symbol libraries are getting to be huge and very cumbersome to manage. Each software package is good at some things, lousy at others. There s no end-all/be-all. Loss of work due to power crashes, viruses, etc. Some software packages require security dongles.

9 Some Popular ECAD Software Companies OrCad ACCEL Technologies Tango, p-cad CadStar Cadence Mentor Graphics Protel CADSoft USA EAGLE IVEX PADS Electronics Workbench CircuitMaker

10 What is PSPICE? SPICE =Simulation Program with Integrated Circuit Emphasis Developed at University of California at Berkeley PSPICE is a derivation of SPICE written by MicroSim (now owned by Orcad)

11 Why we ve chosen to use PSPICE V8 Free functional evaluation version Generally quite easy to use (but limited in complexity & functionality) Can do simulation of some circuits Full professional copy is installed on Lab network (CAD1, PIT1, PIT2, PIT3, PIT9, PIT8) MicroSim Release 8.0 evaluation version is installed on all other PIT & CAD NT Workstations.

12 PSPICE Components Schematic Capture PWB Design Simulation

13 Things to Explore in PSPICE V8 Setting up a new drawing Setting grids and other options Setting up title blocks Placing, moving & rotating entities Zooming and panning Altering component attributes Connecting parts Adding text

14 Typical E-Schematic Design Steps Select Page Size and Title block Setting up the title block Place major component symbols Interconnect component symbols Assign component values Create custom components Perform Electrical Rule Check (ERC) Create a netlist Create Bill of Materials (BOM) Adjust placement for readability

15 Creating Custom Libraries Create component PWB footprint Create schematic graphics symbol Set/alter device attributes Setup ERC functions for each pin Save the new part in a library

16 PSPICE Simulation Example Equal Component Salen Key LPF Special Considerations Use only supplied PSPICE library parts Must use power supply (batteries) Must use special PSPICE ground Must specify PSPICE signal source Must define output signals Must create netlist Run simulation

17 Good Luck! Fred & George