In the last post, we successfully got a laser/sensor pair working with the laser tripwire test. This is great, but my design calls for 72 of these tripwires (36 on the X-axis and 36 on the Y-axis). Unfortunately, the Arduino Uno only has 14 digital input/output pins. So we need to find a way to read signals from 72 phototransistors with only 14 IO pins to work with. In this post, we’ll be testing a method of reading many inputs with just a few Digital Input pins.
The first step toward building my tennis ball sensing board was to test the simplest iteration of the sensor concept: A single laser/sensor combo, that is tripped when an object passes between them, blocking the laser beam. Will an object breaking this beam cause enough of a drop in the phototransistor’s reading to create a digital signal that we can feed into a microprocessor?
Simply put, throw is a project that will consist of a wooden board equipped with laser sensors to determine where objects thrown at the board make contact. It will be connected to a micro-controller and computer to read input and create digital imagery.