The Line Tracker allows your robot to follow a pre-marked path and allows humans to indirectly control the robot while it is autonomous.
The range for the Line Tracker is approximately 0.02 to 0.25in (from the ground) with optimum sensitivity at 3 mm (about 1/8 inch). The minimum line width it can detect is 0.25in.
The Line Tracker is an analog sensor, meaning that it can output many more values within its range of potential values (in this case, from 0-5V) than a digital sensor, which would output only a handful of discrete values in the range (e.g., 1, 2, 3, 4, and 5V), as is the case for a digital sensor. This range of output from 0-5V is sent to the microcontroller, which translates it into a corresponding range of integer values from 0 to full scale. Full scale is 1023 for 10-bit Analog-to-Digital values such as with easyC or ROBOTC for PIC, 4095 for 12-bit values such as with ROBOTC for Cortex and 255 for 8-bit values such as with MPLAB. When using the VEX ARM® Cortex®-based Microcontroller, typical white/black/"away from everything values" will be 38/662/770 for easyC, 153/2650/3076 for ROBOTC and 9/166/192 for 8-bit values. When using the PIC Microcontroller, typical white/black/"away from everything values" will be 38/882/1012 for both easyC and ROBOTC and 9/220/253 for 8-bit values.
For this particular sensor, the output will be low when the surface is pale or highly reflective and high when the surface is dark and absorbs infrared energy.
Line width: 0.25in minimum; optimal line width is 0.5in
Response Frequency: 50Hz
Light Source: GaAs infrared LED with a peak wavelength of 940nm
Receiver: Si phototransistor with a sensing wavelength of 850nm (max)
- Type: Light reflected from dark lines and a bright floor
- Black: ground
- Red: +5V
- White: control signal
Connect to three analog inputs