Data Management Using Viewlogic "ViewDataBook"
Biography: Rich Buckley has 16 years experience designing radio products and systems for commercial and military applications at Harris Corporation. He holds a BSEE from Worcester Polytechnic Institute and an MSEE from Rochester Institute of Technology. His technical interests include rf design, digital signal processing and Electronic Design Automation.
Company:
Harris Corporation
RF Communications Division
1680 University Avenue
Rochester, NY 14610
(716) 242-3473
Abstract: This paper discusses how Harris RF Communications uses ViewDataBook and ViewDataBook II to interface its simulation, layout, purchasing and manufacturing data with Viewlogic schematic capture.
Viewlogic is used throughout the Engineering Department at Harris/RF for printed circuit boards and custom IC designs. The ability to associate the schematic information with other software tools and databases is central to our recent productivity improvements.
The system has been fully implemented, widely accepted and in use for roughly 18 months. The paper discusses lessons learned during this process, including critical success factors, roadblocks, and thoughts on future improvements.
A typical hardware design for a Harris/RF engineer is a pwb for a portable radio application. These designs can include a combination of RF components (1MHz - 1GHz), high speed digital components (60-100 MHz), FPGAs and power supply conditioning. Our engineers are faced with the challenge of getting better products to market faster than in the past.
Upon a brief analysis of our design flow, it was readily apparent that:
· There were too many hardware design iterations (a.k.a. turns), and
· each iteration took too long
Upon investigation of why there were design iterations, three main causes became obvious:
· The schematic did not represent the product (feature changes),
· the schematic was wrong (poor or no simulation), and
· the schematic didn’t match the parts list and/or pwb layout
A group of concerned engineers and drafting personnel met periodically to solve the last two of these issues. The remainder of this paper describes our efforts to date (for the period of June 1995 to December 1996).
Task #1: Make sure the schematic matches the parts list
With modest resources at our disposal, we felt that any solution to this problem would need to borrow as much as possible from existing resources. Our schematic resource was Viewlogic, and our parts list resource was a homegrown, mainframe part database (IMS) and parts list program (PLD). At the time this project was started, our department was using PCs running Windows 3.1.
With the assistance of our Viewlogic sales representative, we learned that a tool called ViewDataBook could be used to search a database of component information. That information could then be applied to a Viewlogic schematic as attributes, which could then be loaded into our parts list program using Viewlogic’s GenPList program. In short,
Harris IMS ---> ViewDataBook ---> ViewDraw ---> GenPList ---> Harris PLD
The Harris IMS system happened to have a great deal of useful information: company part number, description, part cost, purchase usage, etc. We decided that if the engineers would use ViewDataBook, then the generation of parts lists would be a simple matter of running the GenPList utility.
Thus, the problem became “How do we get the engineers to use ViewDataBook?”. The answer was to sell the engineers on the idea that: a) the engineer could use ViewDataBook to find parts, and b) by using the system, the engineer wouldn’t need to maintain a separate PL.
By working with the keepers of IMS (namely, our Components Engineering department), we added new columns to the company database, ones that would help engineers find parts. For example, our “capacitor” columns included:
· P/D_NUM (company part number)
· PRFPRT (preferred part)
· ITEM_DESC (part description)
· VALUE (added)
· VOLTAGE (added)
· TOLERANCE (added)
· PURCHASE_USAGE
· COST
· TECH (surface mount versus through hole)
We added the appropriate columns, filled the information into the 30,000 parts in our database, and worked with our MIS department to generate the necessary “.par" files. These *.par files, one for each commodity (resistor, capacitor, integrated circuit, etc.).
KEY RESULT #1: This method of finding parts was sufficiently superior to the previous methods, that our engineers used the system willingly, especially when promised that this information would then automatically generate parts lists.
Once the attributes were applied to the schematic, the use of GenPList on the finished schematic allowed us to import these schematics painlessly into our company parts database.
KEY RESULT #2: The parts lists were generated electronically, removing the need for engineers and technicians to create and maintain parts lists. As long as the engineer kept the schematic up-to-date, the parts list would automatically follow.
KEY RESULT #3: The parts list matched the schematic upon transfer from the engineer to the draftsperson, saving rework time in Drafting while improving quality.
Task #2: Make sure the schematic matches the pwb layout
It appeared that the same technique would work for the schematic-to-pwb layout interface. For the layout tool at the time (PCAD), we determined that we required 3 additional IMS columns.
· PKG_TYPE
· DEVICE
· SYMBOL
Our Drafting Department filled data into these 3 additional IMS columns, and created any schematic and/or PCAD symbols that did not yet exist.
The increased use of ViewDataBook allowed pwb layouts to start from a more robust point, since the drafting personal no longer had to research parts in order to layout the pwb.
KEY RESULT #4: Front-end Drafting time was replaced by a one-time-ever-per-part creation task. While adding to the Drafting overhead, the pwb turn-around time in Drafting was shortened.
Task #3: Add as much residual benefit as possible
In order to maximize the benefit, we customized a toolbox (in Workview Plus) to simplify the user interface:
· Icon #1 -- Point to the correct file directories
· Icon #2 -- Invoke ViewDraw
· Icon #3 -- Run ViewDataBook
· Icon #4 -- Run the “refdes” utility
· Icon #5 -- View “pcb.err”
· Icon #6 -- Run a “view attribute” utility
· Icon #7 -- View the results of the “viewattb” utility
· Icon #8 -- Run the GenPList utility
When complete, the user is assured that all required files for both the parts list and pwb layout programs are accurate and complete.
RESULT #5: A custom toolbox allows the user to simply perform a sequence of tasks, allowing them to worry about more important design issues, rather than the proper use of the tool. Given a typical user that may do schematic capture 2-3 times per year, making the software easy to use increased both productivity and quality.
Another important software tool for Harris/RF engineers is the EDAnavigator tool from HarrisEDA. This tool allows the engineer to perform a critical part placement subsequent to his/her pass through Drafting. In addition, several advisors can be used to roughly analyze board size, number of layers, trace congestion, shielding/partitioning, and adherence to Design for Manufacture (DFM) rules.
By adding one attribute (component class), our manufacturing engineers were able to define the minimum spacing between different types of components. This ensures that when a critical parts placement is performed, the result will adhere to the company DFM rules.
RESULT #6: Incorporating manufacturing data into our IMS database allows the engineer to design for manufacture without even realizing it, by forcing our software tools to automatically adhere to DFM rules.
Task #4: Handle New Parts Efficiently
Most good engineering designs make use of the latest parts, which means that new parts are required on virtually every design. Using standard Microsoft Office software, we designed an electronic request form and routing system, which ensures that all new part request forms are passed to all parties, and in the correct sequence.
Our typical new part request originates in Engineering, routes to Components Engineering for verification and logging, then routes to our Drafting Department for creation of schematic and layout symbols, if necessary.
While the handling of new parts is a necessary evil, the automatic routing of forms helps to minimize the costs involved.
Task #5: Attach simulation attributes
A natural progression is to add simulation attributes where possible. The first area attacked was that of analog simulation, using ViewSpice. The IMS columns added were those required by the ViewSpice simulator:
· PREFIX
· MODEL
· ORDER
ViewSpice is used at Harris/RF to analyze analog circuits. The use of analog simulation presents a new set of issues to overcome, which include:
· The availability and quality of the model,
· the parameters under which the model was developed, and
· the accuracy required for the circuit and simulation at hand.
Support of digital and mixed-mode designs continues as work in progress. Present efforts include:
· Defining what models exist throughout our department,
· creation of another IMS column (one that contains pointers to the correct model)
Issues concerning the availability of models, the cost of good models and the format of these models versus what various simulators can accommodate continue as present and near-future challenges.
Task #6: The Move to Windows NT, Workview Office and PADS
In order for us to take advantage of the latest software, we found it necessary to upgrade to a WindowsNT platform and Workview Office software. For Harris/RF, it seemed best to upgrade our platform, schematic software and pwb layout software simultaneously. Given the size of our group (roughly 400 people & PCs), the upgrade has been taken in stages, with common areas and Drafting being upgraded first, and the remainder being upgraded as resources permit.
The move to Workview Office necessitated the move to ViewDataBook II. Due to a lack of full backward compatibility, minor alterations were required to our .par files in order to accommodate ViewDataBook II. However, the upgrade was well worth the trouble, with significant improvements in numeric searches, ability to select the symbol from within ViewDataBook II and improved windowing and color schemes. We presently use ViewDataBook II in the same manner as we used the original ViewDataBook.
The use of Workview Office and PADS allows us to pass more attributes between the schematic and the pwb layout. For example, cross-probing between the schematic and the layout is finding uses in several areas:
· Layout verification
· Circuit troubleshooting
· Manufacturing process instructions and rework
· Technical training materials
Areas for Further Improvement:
Despite all of the gains made to date, there are many areas that could stand improvement. Some of these areas are noted below:
RF Simulator Interface: Given the nature of our business, simulation of rf circuits is important and prevalent. Our tool of choice is the HP/EESOF Series IV software, which allows the user to enter schematic information and simulate/optimize as desired. Clearly, schematic capture in two (or more) different software package is inefficient and fraught with synchronization problems. We are presently working with Viewlogic to brainstorm solutions to this issue.
Multiple “Spices”: Engineers tend to have favorite software packages, and this is apparent when one considers the wide number of Spice flavors used in our department. Again, we are working with Viewlogic to understand how the attributes present for use by ViewSpice can be used in the other flavors of Spice.
Managing software upgrades: Given the size of our department, combined with the ever-increasing workload of our MIS department, software upgrades often receive a cooler reception than one might expect. As customers of EDA software become more reliant on the software, the need for fully backward compatible software becomes more important.
Maintaining synchronization with other departments: The successes gained in Engineering have spawned similar efforts in other departments, with varying degrees of success. Initiatives are underway to replace our Manufacturing databases and add a product data management (PDM) system. It is important to ensure that these new databases will integrate properly with the systems put in place to date.
EMI/RFI: As we continue to reduce the size and weight of the systems, crosstalk requires increasing attention. Digital clock signal integrity, power supply noise and RF emissions continue to challenge the engineers and the tools they use. We continue to work with Viewlogic to investigate how Quad Design can be applied to these problems.
Summary:
The use of ViewDataBook is central to out transfer of data among the software tools that we use at Harris. With an ever-increasing number of tools and features, the need for such a software tool will no doubt increase.
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