Building a Typical Electronic
Project in Senior Design
Peter Wihl
(former Guest Lecturer)
Scope
• The purpose of this presentation is to
introduce you to the process of
implementing a circuit design into an actual
working design solution.
Process Overview
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Requirements*
System Architecture*
Component Selection
Mechanical/Packaging Design
Detailed Board Design
Layout
Fabrication
Board Assembly
Testing and Debugging
Design Changes/Workarounds
*Must be completed prior to this process.
Lecture Example
Building a distance measuring sensor device
Requirements
• Must be completed prior to board design
and implementation
• A detailed list of what the system must do
• Not how it does it.
• Should be well thought out and clear
Requirements Example
• Must be wireless
• Must measure in the range from 0.30 to 2.5
meters
• Must have a resolution of at least +/- 10 cm
• Must interface with a microprocessor on
both transmitter and receiver side using
5.0V CMOS Logic
System Architecture
• A detailed block diagram
• Includes all significant signal paths
• Include signal direction, width, and type
System Architecture Example
RF_Pulse
Fc = 433 MHz
RF Tx
RF Rx
RF_Detect
US_Pulse
Tone
Decoder
OpAmp
OSC
40 KHz
Voff = 2.5 V
Vpp = 5 V
Voff = 0 V
Vpp = 2 mV
Voff = 0 V
Vpp = 2 V
US_Detect
Component Selection
• Identify the best component solution for
each design block in the system architecture
• Identify all necessary support components
for each major design block component
• Explore different package options if
available
• Take any mechanical requirements into
account
Component Selection Example
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Reynolds 433 MHz Tx/Rx Module (COTS)
US Transducers Tx/Rx
40 kHz Crystal
74’Inverter
74’NAND
LMV722 OpAmp from National
LMC567 Tone Decoder from National
Headers
SM Resistors and Caps
Mechanical/Packaging Design
• Identify the mechanical or packaging
requirements of your design
• May possibly have to select components
based on these requirements
• Identify possible layout restrictions
• Think about non-circuit requirements, i.e.
mounting and packaging
Mechanical Design Example
Mechanical Design Example
Mechanical Design Example
Mechanical Design Example
Mechanical Design Example
Detailed Board Design
• Build your schematics in a schematic
capture program e.g. OrCAD
• Once your schematic is complete run a
design rule check (DRC)
• When schematic is done convert to netlist
for layout
Detailed Design Example
Detailed Design Example
Layout
• The process of designing the PCB
• Requires a schematic netlist, the “Bill of
Materials” or BOM and all package
mechanical information
Layout Example
Fabrication
• This is the process of placing the
components on the PCB
• Can be done by hand or machine
Fabrication Example
• See sample
Board Assembly
• The process of populating the PCB with all
components
• This includes ICs, Resistors, Caps
Connectors and LEDs, etc.
Board Assembly Example
Testing and Debugging
• You need to develop a thorough and
complete test plan for your board.
• Should include a check list of steps in a test
procedure
• Each step should include status of all board
voltages
• Use continuity, clock signals and/or
signature analyzer to verify net connections
Design Changes/Workarounds
• White wire part of the board
• Must create detailed step by step
instructions on white wire corrections
• Sometimes minor design changes are
needed when an error is found in the board
design
• May have to be done in software
Conclusion
• This process consists of different types of
engineers working together.
• Depending on system complexity and level
of design reuse this process can take from 1
to 18 mouths.
• Any questions?