CHAPTER 6. Working with time
interrupts, counters and timers
Apart from the lucky few, our daily lives are ruled by time. We have alarm clocks to wake us in the morning, stopwatches to measure time duration, timers to start off single events (such as a VCR recording) and timers to maintain periodic events (such as a house heating system coming on at the same time every day). For the young and those who teach, the working day is ruled by a school timetable – a complex series of timed events.
For embedded systems, time is similarly of the essence. At a simple level the system needs to respond in a timely manner to external events. It may also need to measure time between external events and generate time-based activity. These requirements are ...