Redesign presents creative opportunities for electrical engineers.
Redesign of aging electronic products presents unique challenges and creative opportunities to electrical engineers. For a complex electronic product, the quality of the redesign effort often rests in how well the redesign-engineering team understands how the design should be updated. Study of the original electronic design is necessary; understanding how the original equipment functions, and what design choices the original engineering team applied to achieve that functionality is essential.
Orchid Technologies Engineering and Consulting, Inc. completed the redesign of the precision LCR instrument shown in the photograph below. Accurate to 0.05 percent of full scale, the original 1988 instrument design was very well executed. However vintage 1980’s state of the art electronic components were going end-of-life at an alarming rate.
The first step was to study the existing design. Designers worked to put themselves into the minds of the original designers. Through a process of study and review a redesign approach was identified. A detailed development plan was generated that proposed significant technical improvements and cost reductions.
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Three primary technical opportunities became clear:
- Update the aging DSP Processor Design.
- Modernize Analog Amplifier Components.
- Implement old Digital Logic with an FPGA.
The original product contained an older Texas Instruments TMS320C31 processor. Running at only 33 MHz, the 32 Bit Digital Signal Processor (DSP) represents floating point numbers in a Texas Instruments’ proprietary manner. Old upper level software performed floating point numeric conversions to make use of the DSP’s calculations.
Redesign gave the opportunity to replace the old DSP with a new Texas Instruments TMS320C6713 that performs at 200 MHz, and represents floating point numbers in standard IEEE format. Old DSP firmware was ported to the new processor using Texas Instrument’s Code Composer Studio environment. The result, a new design that performs more than six times as fast as the original instrument.
Twenty years ago, the original product was designed using Analog Devices’ 24 bit DDS (Direct Digital Synthesis) devices, which are highly complex electronic components that generate spectrally pure sine waves, using digital numeric lookup tables, at any programmable frequency.
Today Analog Devices’ modern DDS components make use of 48 bit look up tables. Such DDS devices provide incredible frequency granularity and purity.
Almost every older electronics product contains MSI (medium scale integration) and SSI (small scale integration) electronic components. Parts of this type are the familiar 7400 series quad or dual logic function component. Often such logic components are package in large dual in line through-hole technology packages. Multiple circuit boards are often required in older design just to fit the large sized component parts. Today’s opportunity is to collect those MSI and SSI parts into a single, far smaller programmable logic device.
In the LCR meter design, the functions of a 48 square inch board into a single 0.9 square inch programmable device from Altera were combined. The result was two fold. First, product cost was reduced by requiring fewer circuit boards in the overall design. Second, digital noise was reduced, improving system accuracy.
Through these techniques and others, Orchid Technologies has helped nation wide client base maintain their product portfolio.
For more information visit www.orchid-tech.com