Transcript Document

Reflectance Sensor Array:
Line sensing
Team: Grounded
Rachel Kmetz, Matthew Forsyth, Austin Meirick, and Levi Eisel
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Line Sensing
What are we not doing?
-Steering
-Speed
-Noise
-Tracking
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Each module carries eight IR
emitters and receivers.
Outputs are all independent
The LEDs are controlled by
MOSFET, that are normally
pulled high.
Operational Voltage: 3.3 –
5.0V
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Supply current is 100mA
Note: The optimal sensing
for the QTR-8RC is 0.125”
about 3mm. The QTR-8RC
can NOT be placed to close
nor to far from the black line
this could warp data.
The maximum sensing
distance is around .374”
about 9.5mm.
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The same pins appear in
different locations but you
don’t have to connect to all
of them.
Vcc and GND are where the
sensor gets power. Vcc must
be between 3.3-5v.
IR LEDs achieve optimal
brightness at 5v.
LEDON is connected to the
MOSFET and gives power to
the IR LEDs. When this pin
is high, all the LEDs are on.
16-Conductor Ribbon Cable:
You will use this to connect from the
QTR-8RC to the 16-pin Ribbon cableto- breadboard Adapter.
• IR Array Mounting Bracket :
Mounts the QTR-8RC to the “SmartCar”
• 16-pin Ribbon cable-to-Breadboard
Adapter
• Items used in mounting.
• QTR-8RC: Our reflectance sensor array
that are intended for line sensing.
Below is pictures and commentary about how to
mount the QTR-8RC to your “SmartCar”
•Figure2: You need to place the IR
mounting bracket on the front of the car.
From the IR bracket you need to add
spacers and secure them to both the IR
bracket and the QTR-8RC.
•These spacers will get the QTR-8RC to
the correct height above the line.
•You have now mounted your QTR-8RC
Figure 1: View from the front of
the car.
 Connect 5volts and ground from
ColdFire to the ribbon cable adaptor.
Make sure you check continuity of
the ribbon cable to the QTR-8RC
before you connect the 5 Volts.
 You then need to map your ports
from the ribbon cable to the QTR8RC and the 8 bit output port, such
as port B or E.
QTR-8RC
BLACK LINE
QTR-8RC
WHITE SPACE
Note: This is when all 8 of the IR Receivers are over top of either
the while space or the back line.
This is the oscilloscope print out of the QTR-8RC over the black line and some
white space. Look at how lines 8,9,13,14,15 are significantly lower than lines
11,12. This is because those lines are over the white space, unlike lines 11,12
they are the black line.
Drive the I/O line high and make it an output.
 Allow 10us for the capacitors to charge.
 Make the I/O line high Impedance (an input)
 Wait for the I/O line to go low, then measure
how long it takes for the capacitor to
discharge.
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Qtr-8A And Qtr-8Rc Reflectance Sensor Array User's Guide, and
© 2001–2009 Pololu Corporat. Pololu - QTR-8A and QTR-8RC
Reflectance Sensor Array User's Guide (n.d.): n. pag. Web
Pololu Qtr Reflectance Sensor Application Note, and © 2001–2009
Pololu Corporat. Pololu - Pololu QTR Reflectance Sensor Application
Note(n.d.): n. pag. Web.