Fire Bird V ATMEGA2560 Hardware Manual
Figure 3.37: IR Proximity sensors
Figure 3.37 shows IR proximity senator’s circuit. IR proximity sensors 1 to 5 are connected to m
the ATMEGA2560 main microcontroller and IR proximity sensors 6 to 8 are connected to the
ATMEGA8 slave microcontroller.
Power switching circuit for IR Proximity sensors is shown in bottom left corner of figure 3.37.
Sensors can be permanently turned by inserting jumper. For location of the jumper, refer to
figure 3.38. You can turn on / off this sensor if this jumper is open. If logic 1 is applied to the
base of the transistor T3 by the microcontroller then it goes in to saturation and pulls base of the
transistor T4 and turns off the T4 and IR proximity sensors. When no signal is applied transistor
T3 remains off hence resistor R96 drives transistor T4 in to saturation and T4 turns on the IR
proximity sensor's IR LEDs.
Important:
You can also use IR proximity sensor's photo diode as directional light intensity sensor by
turning off IR LEDs. You can also remove effect of ambient light on the proximity detection by
taking reading while IR LED is on and off and checking difference between the readings.
© NEX Robotics Pvt. Ltd. and ERTS Lab, CSE, IIT Bombay, INDIA 46
