Transcript Sensors 1

Basic Anatomy of a Sensor System
Sensor
Sensor
Sensor
Signal
Conditioning
A/D
Analog
Mux
A/D
H/L
Control Bus
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8 bit Analog to Digital Converters
Share A/D via analog multiplexer
Analog signal conditioning
Microprocessor
Sensing Challenges
Challenge
Potential Approaches
Inadequate voltage / current
Op Amp, buffer, transistors
Noise
Low Pass Filter
Bouncing
S/R Latch
Capture Signal
Sample & Hold
Limited Sampling Rate
New sensor
8 bit A/D limited to 256 levels
Vary op-amp gain by switching in
resistors with an analog mux
Switch
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As easy as on / off, right? ...nope signal bounces
Switch
Temperature
MTS102 (available in parts shop)
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Linear temp response
Use Diff Amp with V2 = 0.637mV, V1 = buffered MTS102 output, R1=1k, R2=40k
Vbe vs. Temp
700
Vbe Voltage (mV)
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650
600
550
500
450
400
0
50
100
Temperature (C)
Infrared
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Modulate infrared LED at 40kHz
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LM555 Timer / LC circuit
Columnate LED with Bic Pen
Hack Sharp GP1U58X to obtain analog output reading
(may be obsolete)
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(http://www.mil.ufl.edu/imdl/handouts/sharphack.pdf)
LED
40kHz
Modulation
Bic
Sharp IR
Sensor
1.5V to 2.5V output
100ms Rise time
Obtaining Datasheets
Manufacturers Home Pages
 Data Bookshelf
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(http://www.crhc.uiuc.edu/~dburke/databookshelf.html)
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Links to Manufacturer’s homepages and other resources
Datasheet Repositories
www.questlink.com
 www.tds-net.com
 www.info-quick.com
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