What is the Difference Between Timer and Counter?

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The main difference between a timer and a counter lies in their purpose and functionality:

  • Timer: A timer is a device that measures the passage of time and is typically used to generate a time delay or to measure intervals of time. It counts down from a specified time interval and is triggered by a clock signal. Timers are used to create delays or to measure intervals, such as in the case of an hourglass or a stopwatch.
  • Counter: A counter is a device that stores (and sometimes displays) the number of times a particular event or process has occurred with respect to a clock signal. It is used to count events happening outside the microcontroller, such as external inputs or events.

Some key differences between timers and counters include:

  • Timers are used to generate delays, while counters are used to count external events.
  • Timers typically have a higher maximum count rate than counters. For example, a timer's maximum count rate might be 1/12 of the oscillator frequency, while a counter's maximum count rate might be 1/24 of the oscillator frequency.
  • In some embedded systems, timers and counters share the same hardware but serve different purposes.

In summary, timers are used to measure and generate time intervals, while counters are used to count external events. Although they share some similarities, their primary functions are distinct.

Comparative Table: Timer vs Counter

Here is a table comparing the differences between a timer and a counter:

Feature Timer Counter
Purpose Measures and keeps track of time intervals Counts events from an external signal or an internal clock
Mode Operates in timer mode (incrementing on timer frequency ticks) and counter mode (incrementing on external or internal events) Operates only in counter mode
Capabilities 1. Increment/decrement based on timer frequency or external/internal events.
2. Can be used as a general-purpose timer or counter.
3. Implements capture/compare registers for precise measurements.
1. Increment/decrement based on external/internal events.
2. Useful for counting rapid events or tracking the number of rotations of a high RPM motor.
Interrupts and Events Generates interrupts and events based on timer/counter values. Generates interrupts based on compare channel matches and underflow conditions.

Timers are more versatile than counters, as they can operate in both timer and counter modes. In timer mode, the timer's internal counter register is incremented by one for every tick of the timer frequency. In counter mode, the timer's internal counter register is incremented by one each time the COUNT task is triggered.

Counters, on the other hand, are designed primarily for counting events from an external signal or an internal clock. They can be used for counting rapid events or tracking the number of rotations of a high RPM motor.