Line detection

We designed three custom PCBs to handle field boundary detection, each equipped with TEPT5700 phototransistors. These sensors were selected because they are sensitive to ambient light. This allowed us to detect the contrast between the field lines, which reflect more ambient light, and the darker background of the field surface. To enhance the reliability of this detection, it is important that the LEDs on the line sensor PCBs are ultra-bright, as this increases the intensity of light reflected from the field lines and improves the contrast that the phototransistors can detect. To minimize the number of pins used on our main controller, two of our line-sensing PCBs incorporated a 74HC051 multiplexer, which allowed us to read multiple phototransistor signals efficiently using fewer microcontroller inputs. When sourcing or ordering components, future teams should take great care not to confuse the 74HC051 multiplexer with similarly named components such as the 74HC52 shift register. A multiplexer selects between multiple input channels, while a shift register outputs serial-to-parallel data; these devices serve entirely different functions and are not interchangeable.