Digilent 240-037P - Manual

I I R R R R a a n n g g e e S S e e n n s s o o r r R R e e f f e e r r e e n n c c e e M M a a n n u u a a l l
Revision: October 31, 2011
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Overview
The IR Range Sensor is a great way to add
range detection to robotic projects that use
Cerebot boards. The sensor detects reflective
objects 10 to 80 cm away.
Features include:
•
a Sharp 2Y0A21 infrared sensor
•
Futaba-style 3-pin connector
•
an 8” Digilent cable
Functional Description
The IR Range Sensor is a three-terminal
device that generates an analog voltage
representing the distance to a reflected object.
The sensor connects to the ADC found on all
Cerebot boards. The cable maps the output
pins to a 3-pin connector. The yellow wire is for
the analog output signal. The pin should be
connected to the analog-to-digital converter
(ADC) on your microcontroller. The red wire is
the Vcc power supply to the sensor and is
diode-protected against reverse polarization.
The black wire should be connected to the
ground of the ADC.
Use a 4.5V to 5.5V power supply for the IR
Range Sensor. The sensor’s Vcc input range is
0.3V to 7V, and the analog output is 0.4V to
3V, depending on the distance to the object.
Note: When using more than one IR Range
Sensor, additional bypass capacitors should be
used between Vcc and ground to filter out the
switching noise generated by the sensor on the
Vcc supply line. See the Sharp 2Y0A21
datasheet for recommended capacitor sizes.
Cerebot Interface
The Cerebot II’s ADC analog pins are
connected through servo pins S1-S8. Plug the
IR Range Sensor directly into the onboard
servo header, or use a PmodCON3 to connect
up to four sensors via JH pins 1-6 or 7-12.
The Cerebot MX-series boards require a
PmodCON3 to access the Futaba-style
connectors on the analog ports. The
PmodCON3 exposes four ADC analog
channels to the connectors. The PmodCON3
can be used on any Pmod header with ADC
analog pins.