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Intermediate Topic 23 of 50 Mobile, Embedded & IoT

Timers and Counters

Hardware blocks measuring time and events.

How it works

Hardware timers and counters are peripherals that count clock pulses independently of the CPU. A timer divides the system clock with a prescaler and counts up or down to a compare value, generating interrupts or toggling pins at precise intervals; modes include periodic, one-shot, PWM generation, input capture, which timestamps external events and output compare. A counter counts external edges, such as pulses from an encoder or flow sensor. Watchdog and real-time clock timers provide system supervision and calendar time.

Where it is used

Scheduling tasks, measuring pulse widths and frequencies, generating PWM and waveforms, debouncing, motor control, timeouts and system ticks for RTOS use timers.

Common pitfall

Counter overflow wraps around, so compute intervals with unsigned arithmetic and handle rollover. Choosing prescaler and reload values by hand can cause rounding errors in frequency. Reading multi-byte counters while they change can give torn values. Interrupt latency adds jitter. Use hardware features rather than software delays for accuracy, and verify with an oscilloscope.

Where it fits in the course

Timers and Counters is topic 23 of 50 in Mobile, Embedded & IoT, rated Intermediate. It follows Interrupts in Embedded Systems. The next topic is Embedded C.

Practice and explore

How to study this topic

  1. Read the explanation above and restate the definition in your own words.
  2. Open the interactive lesson and answer its mini quiz.
  3. Read the common pitfall, then write a short example that avoids it.
  4. Check your understanding in the Mobile, Embedded & IoT quiz, and revisit the topic if you miss a question.

Frequently asked questions

What is Timers and Counters?
Hardware blocks measuring time and events. It belongs to Mobile, Embedded & IoT and is an intermediate-level topic.
Where do people use Timers and Counters?
Scheduling tasks, measuring pulse widths and frequencies, generating PWM and waveforms, debouncing, motor control, timeouts and system ticks for RTOS use timers.
What is the most common mistake with Timers and Counters?
Counter overflow wraps around, so compute intervals with unsigned arithmetic and handle rollover.
What should I learn before this topic?
Start with Interrupts in Embedded Systems, the topic just before it in Mobile, Embedded & IoT.
How can I practice it?
Answer the mini quiz in the interactive lesson, then take the Mobile, Embedded & IoT quiz.
Is Timers and Counters hard to learn?
It is an Intermediate topic. Be comfortable with the Beginner topics in this area first, then read the common pitfall carefully, since it is where most mistakes happen.
How long does it take to learn Timers and Counters?
Most learners can read the explanation and finish the interactive lesson in under an hour. Fluency comes from applying the idea, so plan a few short practice sessions with the quiz.
Which topics are related to Timers and Counters?
Interrupts in Embedded Systems, Embedded C, Serial Communication are closely connected. The full list is in the related topics section of this page.
What should I study after Timers and Counters?
Continue with Embedded C, the next topic in Mobile, Embedded & IoT.

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