NEX ROBOTICS FIREBIRD V ATMEGA 2560 Hardware Manual page 45

Fire Bird V ATMEGA2560 Hardware Manual
3.11 Infrared proximity and directional light intensity sensors
Infrared proximity sensors are used to detect proximity of any obstacles in the short range. IR
proximity sensors have about 10cm sensing range. These sensors sense the presence of the
obstacles in the blind spot region of the Sharp IR range sensors. Fire Bird V robot has 8 IR
proximity sensors. Figure 3.36 shows the location of the 8 IR proximity sensors. Sensors are
numbered as 1 to 8 from left to right in clockwise direction. In all the manuals same numbering
convention will be used for addressing the particular IR sensor.
In the absence of the obstacle there is no reflected light hence no leakage current will flow
through the photo diode and output voltage of the photo diode will be around 3.3V. As obstacle
comes closer, more light gets reflected and falls on the photo diode and leakage current flowing
through the photo diode starts to increase which causes voltage across the diode to fall.
Figure 3.36: Eight IR proximity sensors on Fire Bird V
When enabled 8 IR proximity sensors combined together consumes about 51mA current. You
can save power by turning on theses sensors only when required. Refer to table 3.11, these
sensors can be turned off by applying logic 1 (5V) to the pin no. 34 of the main board. To enable
these sensors permanently connect the IRP jumper on J1 of main board. For jumper location
refer to figure 3.38.
© NEX Robotics Pvt. Ltd. and ERTS Lab, CSE, IIT Bombay, INDIA 45