CP316: Microprocessor Systems and Interfacing

Counting and Timing

Timing

• used for
  • measuring time
  • event logging
  • task synchronization
  • controlled delays
• implementation
  • software loop
  • polled timer
  • interrupt timer
• how accurate do you need the time?

Counting

• uses
  • measure speed by counting revolutions of a rotating shaft per unit time
  • interface to a flow meter that generates pulses at a rate dependent on flow
  • measure power output from an electricity meter
  • count objects entering/leaving a system
  • calibrate the position of printing on packaging by counting print head pulses
• what do you 'count'
  • event count
  • elapsed time
  • period count
  • frequency count