NEX ROBOTICS SPARK V ATMEGA16 Hardware Manual page 24

SPARK V ATMEGA16 Hardware Manual
= 6.42 degrees per count
Figure 3.15: Position encoder schematics
3.9 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. Spark V robot has 3 IR proximity sensors.
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 photodiode will be around 5V. 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.
If IR LEDs are disabled using jumpers then same photo diodes works as directional light
intensity sensors.
Figure 3.16: Infrared proximity and Directional light intensity sensors and Jumper settings
for enabling IR Proximity sensors
Figure 3.6 shows 3 Infrared proximity and Directional light intensity sensors on the Spark V
robot. Sensors are numbered as 1, 2 and 3 from left to right in clockwise direction. In all the
manuals this numbering convention will be used for addressing the particular IR sensor.
© NEX Robotics Pvt. Ltd. and ERTS Lab IIT Bombay, INDIA 24