Back in the day where the microprocessor was our standard building block, we tended to concentrate on computation and processing of data and not so much on I/O. Simply put there were a lot of things we had to get working just so we could then read the state of an I/O port or a counter.
Nowadays the microcontroller has taken care of most of the system level needs with the luxury of built in RAM memory and the ability to upload our code. That leaves us able to concentrate on the major role of a microcontroller: to interpret something about the environment, make decisions, and often output the result to energize a motor, LED, or some other twiddly bits.
Often the usefulness of a small microcontroller project depends on being able to interpret external signals in the form of voltage or less often, current. For example the output of a photocell, or a temperature sensor may use an analog voltage to indicate brightness or the temperature. Enter the Analog to Digital Converter (ADC) with the ability to convert an external signal to a processor readable value.
First, he prototyped a single beam-break detector (shown above) and then expanded his build to two in order to get velocity info. A Propeller microcontroller took care of measuring the timing. Then came the gratuitous statistics. He took six different darts and shot them each 21 times, recording the timings. Dart #3 was the winner, but they all had similar average speeds. You’re not going to win the office NERF war by cherry-picking darts.
