TIMER_A: Introduction
Time is an important concept in the real world. Many of the technologies used today utilize measuring time for various applications, such as digital timepieces (like clocks or stopwatches), metronomes, and even navigation. In fact, measuring time is crucial for the operation of Global Positioning System (GPS).
GPS uses the concept of trilateration in order to pinpoint your location, as shown here. If you knew you were (for example) 100 miles away from a point A, then you could be 100 miles away from A in any direction. If you plotted every possible location you could be from A, a circle with a radius of 100 miles would be formed around A. Suppose you knew your distance from two other points B and C. Applying the same procedure would create circles around B and C. The point at which all three circles intersected would be your location.
For the application of GPS, these three points would instead be satellites. There are a multitude of satellites orbiting the Earth, each transmitting data about its current location. This data is transmitted at the speed of light. In order to know how far you are from each satellite, your GPS receiver calculates how much time it took to receive the data. Since the speed of light is known, your GPS receiver can then determine how far you are from a given satellite. Then, trilateration is applied to determine your exact location.
(Source: http://www.physics.org/article-questions.asp?id=55)In this section, we learn about a new timer, Timer_A, that is equipped with extra hardware to measure time even more accurately than we are able using Timer32. This timer can also help with controlling systems using Pulse Width Modulation. In the next subsection, we learn about PWM.Â