Printed Circuit Board (PCB)
Design
Lecture 17
Microprocessor-based Systems (E155)
Prof. Josh Brake
Survey Feedback
• Most important things you’ve learned
• Datasheets!
• Understanding the ”plumbing”
• Things still unclear
• Interrupts
• Redundancy/error checking
• CMSIS
• Things to change
• Start earlier
• Refreshers
TBD lectures no longer TBD
• Direct Memory Access (DMA)
• Load from or store to memory without using CPU
• Real-time operating systems
• Why?
• Multi-tasking
• Scheduling
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Outline
• What is a PCB?
• History
• Components
• PCB Design process
• Layout considerations
• KiCad Demo
• Further resources
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Why PCBs?
AP Physics B Final Project: Wire Wrapping by Andrew Adams under CC BY-SA 2.0 4
Components
• Two main types
• Through-hole
• Surface mount technology (SMT)
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Helpful Terms
• Trace – copper ”wire” on board
• Via – hole through the board
• Pad – exposed copper area where part is soldered
• Package – physical size of part and pins
• Surface mount – part which is attached to one side of PCB
• Through-hole – part which is inserted through PCB
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PCB vs. Breadboard
• Pros for PCB
• Stability and reliability
• More space efficient
• Better grounding
• Physical mounting is more stable
• Pros for breadboard
• Flexible
• Ease of debugging and isolating problems
• Fast!
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Ways to manufacture
• Etching
• Milling
• Printing
http://www.webshop.mipec.eu/fotky6870/fotos/_vyrp14_71DSC_7924.jpg
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PCB Structure
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Design Process
Budget around 6-8 weeks per iteration if you
are new at it.
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Create/Import Symbols
• Open eeschema
• Add/create libraries
• Select or import symbol
• Symbols for many common parts already
exist
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Schematic Capture
• Layout components
• Then go and connect with
wires or labels
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Create/Import Footprints
• Connect schematic symbols to their physical shape
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Generate Netlist
• Gives list of network connections between components
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Board Layout
• Open PCB new and import schematic
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Production
• Check out the Gerber with an online viewer
• Gerber file is industry standard file for machines with manufacture
PCBs
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Layout Considerations
• Trace Widths
• Decoupling capacitors: Rules of thumb
• ~10 µF for next to power inputs
• 10-100 nF next to ICs
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KiCad Demo
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References
• https://cei-lab.github.io/ece3400-2018/lectures/Lecture15-
PCB_Design.pdf
• https://ocw.mit.edu/courses/mechanical-engineering/2-996-
biomedical-devices-design-laboratory-fall-2007/lecture-
notes/lecture02.pdf
• https://www.protoexpress.com/blog/7-pcb-design-tips-solve-emi-
emc-issues/
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Further Resources
• Shawn Hymel YouTube series - KiCad Digi-Key Tutorial
• Chris Gammel Video series - Getting to Blinky 4.0
• Prof. Spencer PDF - How to make a PCB for me
• Clinic Tutorial
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Up Next
• Wednesday: Motors and Speakers
• Lab 7: The Internet of Things
• Final project proposal due today
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