ECE 453 Embedded Microprocessor System Design

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ECE 453Embedded MicroprocessorSystem Design
Week 5

• Michael G. Morrow, P.E.

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Whats Happening in ECE 453?

• This Week
• Lab Exercise
• TLL6219 Software Applications
• Detailed Proposal due Friday by 500pm
• See me/Dan beforehand if you have questions
• Next Week
• Lab
• Linux Apps for Hardware
• Plexus Visit on Friday 2/27
• Depart 945am from Union South

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Week 5 Topics

• Component Selection
• Layout and Support Circuits
• Power Supplies
• Interfacing to Displays

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Hofstadters Law

• It always takes longer than you expect, even when
  you take Hofstadters Law into account.

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Quotes

• "An effective way to test code is to exercise it
  at its natural boundaries" Brian Kernighan
• "Program testing can be used to show the presence
  of bugs, but never to show their absence!"
  Dijkstra
• "Testing is the process of comparing the
  invisible to the ambiguous, so as to avoid the
  unthinkable happening to the anonymous." James
  Bach

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Resistors

• Characteristics and Specification
• What characteristics do we need to specify when
  selecting a resistor?
• Resistor Markings
• Through-hole components
• SMT components
• Selection and Usage
• Power Dissipation
• SMT Chip Resistors

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Capacitors

• Characteristics and Specification
• CeA/d
• ESR/ESL
• Capacitor Types
• Film Capacitors
• Ceramic Capacitors
• Electrolytic
• UltraCapacitors

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Inductors

• We spend most of our time getting rid of
  inductance in our digital circuits, but it does
  have its uses
• Power supplies for mixed-signal circuits
• Ground noise issues
• Conducted radiation issues
• Inductors are heavily used in switch-mode power
  supply (SMPS) designs more on that later

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Power Supply Bypassing

• The Issues
• CMOS synchronous circuits draw current in large
  spikes near the clock edges, and very little in
  between
• Capacitance charging/discharging
• Switching (shoot-through) currents
• The current drawn by a device is essentially
  proportional to the number of transistors
  changing state ? more activity more current
• Solutions
• Decoupling Capacitance
• Bulk Capacitance

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Layout and Support Circuits

• Circuit Layout
• Wire Selection
• Power and Ground Distribution
• Daisy-Chain
• Star
• Rails
• Planes
• Mixed-Signal Systems
• Logic
• Inputs
• Outputs
• Clock Circuits

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Power Supplies

• Functions and design considerations
• Voltage references
• Linear regulators
• Inductor-based SMPS
• Buck converters PWM operation PFM operation
• Boost converters Operation
• Flyback converters
• Capacitor-based SMPS (charge pumps)
• The size of reactive components in SPMS is a
  function of frequency

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Power Supplies (continued)

• Batteries
• Terminology
• Primary versus secondary cells
• Chemistry
• Alkaline and Carbon Zinc
• Lead-acid
• NiMH / NiCad
• Lithium Primary Cells
• Lithium Ion
• Power Supply Sequencing
• CMOS inputs
• Protection diodes
• Power flow

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Display Technologies

• Liquid-Crystal Displays (LCD)
• Cholesteric LCDs
• Light-Emitting Diodes (LED)
• Vacuum Fluorescent (VFD)
• Cathode-Ray Tube (CRT)
• Incandescent Lamps
• Plasma Displays
• Cold-Cathode Fluorescent (CCF) / EL
• Organic Electroluminescent (OEL)
• Digital Micromirror Devices (TI DLP)
• Etc...

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Display Types

• Annunciator
• True/false, on/off indication
• Numeric
• i.e. 7-segment displays, numeric data
• Textual (Character-Based)
• i.e. dot-matrix, 14-segment displays, limited to
  fonts
• Iconic
• Fixed graphic elements
• Graphic
• Each pixel individually addressable, arbitrary
  display

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LCD Displays

• Numeric, text, iconic, and/or graphic
• Extremely low power
• Passive
• Temperature sensitive
• Complex drivers needed to create segment voltages
  on multiplexed displays
• Require no net DC offset on segments on single
  polarity systems this adds to complexity
• LCD modules versus LCD glass

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LCD Technology

• A combination of polarizing filters and twisted
  liquid crystal creates a liquid crystal display.
• TN (twist nematic) display

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LCD Architecture

• Display drive organizations
• Reflective, transmissive and transflective
• Monochrome versus color
• Selection parameters
• Resolution
• Viewing angle
• Contrast
• Brightness (transmission)
• Response time / frame rate
• Operating temperature range

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Wrapping Up

• Next week in ECE 453
• Lab ????
• Sensors, Audio and Speech
• Plexus trip on Friday 2/27/2009
• Depart from Union South at 945am
• Return to UW around 600pm
• Resume?

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Alkaline Carbon Zinc

• Low-cost primary cells
• VCELL 1.55-1.6V
• RINT 0.2O (D alkaline)
• Capacity
• IEC/ANSI tests

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Alkaline Carbon Zinc (cont)

• Capacity is a function of discharge rate,
  terminal voltage, and temperature

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IEC/ANSI Battery Tests
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Lead-Acid

• Secondary cells
• VCELL 2.3V
• Low cost, high energy density, rugged
• High current capacity
• Off-gassing

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NiMH / NiCad

• Secondary cell
• VCELL 1.25V
• Low RINT (D-cell 0.01O)
• Discharge characteristics

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NiMH / NiCad (cont)

• Self-discharge
• Charging
• Fuel gauges
• NiCad vs. NiMH

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Lithium Primary

• Primary cell
• VCELL 1.5V, 3.0V, 3.6V
• Numerous chemistries
• Storage
• RINT

2L76
CR2032
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Lithium-Ion

• Secondary cell
• VCELL 3.6V
• Storage
• Support circuits
• Charging
• Gauging
• Protection

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Lithium Battery Management
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Boost Switcher Topology

• VOUT gt V

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Buck Switcher Topology

• VOUT lt V

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Buck Switcher (25V ? 5V, PWM)
iL
vL
iout
iin
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Buck Switcher (25V ? 5V, PFM)
iL
vL
iin
iout
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Boost Switcher (3.6V ? 27V)
iiniL
iout
vout
vL
vin
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Flyback Switcher Topology

• Transformer provides isolation and voltage
  increase/decrease.

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Color TFT LCD
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LCD Pixel Drive Organizations
Passive matrix
Static (waveforms)
Multiplexed (waveforms)
Active matrix
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Resistor Power Dissipation
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Chip Resistor Construction
Source Walsin Technology Corporation http//www.p
assivecomponent.com/product/document/Chip-R/wrxx2
0general.pdf
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Power and Ground Distribution Daisy-Chain
vcc
vcc

-
gnd
gnd
vcc
gnd
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Power and Ground Distribution Daisy-Chain with
Impedance
Z
Z
vcc
vcc

digital
analog
-
gnd
gnd
Z
Z
Z
Z
vcc
digital
gnd
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Power and Ground Distribution Star
vcc
vcc

-
gnd
gnd
vcc
gnd
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Power and Ground Distribution Railed
vcc
vcc

-
gnd
gnd
vcc
gnd
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Power and Ground Distribution Planes
vcc
vcc

-
gnd
gnd
vcc
gnd
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Static LCD Drive
http//ww1.microchip.com/downloads/en/devicedoc/41
265a.pdf
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LCD ½ Mux½ BiasDrive
http//ww1.microchip.com/downloads/en/devicedoc/41
265a.pdf
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Film Capacitors
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Ceramic Capacitors
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Ceramic Capacitor Dielectrics
Y5V
X7R
X5R
COG(NPO)
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Electrolytic Capacitors
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Ultracapacitors