Introduction to RTOS Part 8 - Software Timer | Digi-Key Electronics

In embedded systems, timers offer the ability to delay a call to a function, periodically call a function, or control some peripheral without the need for CPU intervention. In FreeRTOS, a software timer is controlled by a timer service task and can be used to execute a function some time in the future based on the RTOS tick timer.

The solution to the challenge in the video can be found here: https://www.digikey.com/en/maker/projects/introduction-to-rtos-solution-to-part-8-software-timers/0f64cf758da440a29476165a5b2e577e

Code for this video series (including demonstrations, challenges, and solutions) can be found here: https://github.com/ShawnHymel/introduction-to-rtos

FreeRTOS gives us a software timer library that we can use to configure several timers. These timers are tied to the tick timer, so we cannot get a resolution greater than the tick timer’s resolution (1 ms by default in the ESP32 Arduino package).

When we include the timer library, it will automatically spawn a timer service (or “daemon”) task that runs at priority 1 (default in ESP32 Arduino package). This service task is in charge of managing all of the software timers that are set.

Timers can count up or down and can be set to “one-shot” or “auto-reload.” Whenever a counter reaches its maximum value (as set in code), it will execute the callback function associated with that timer. A “one-shot” timer will execute the callback function only once, unless the timer is told to start counting again. An “auto-reload” timer will execute the callback function periodically at a rate specified by the timer’s max value.

In the video, we demonstrate the use of software timers and explain how they function within FreeRTOS. We also issue a challenge to create an auto-dimming LED feature whenever an interface is not being used.

Product Links:
https://www.digikey.com/en/products/detail/adafruit-industries-llc/3405/7244967

Related Videos:
Introduction to RTOS Part 1 - What is a Real-Time Operating System (RTOS)? - https://youtu.be/F321087yYy4​

Introduction to RTOS Part 2 - Getting Started with FreeRTOS - https://youtu.be/JIr7Xm_riRs​

Introduction to RTOS Part 3 - Task Scheduling - https://youtu.be/95yUbClyf3E​

Introduction to RTOS Part 4 - Memory Management - https://youtu.be/Qske3yZRW5I​

Introduction to RTOS Part 5 - Queue - https://youtu.be/pHJ3lxOoWeI​

Introduction to RTOS Part 6 - Mutex - https://youtu.be/I55auRpbiTs​

Introduction to RTOS Part 7 - https://youtu.be/5JcMtbA9QEE​

Introduction to RTOS Part 8 - https://youtu.be/b1f1Iex0Tso

Introduction to RTOS Part 9 - https://youtu.be/qsflCf6ahXU

Introduction to RTOS Part 10 - https://youtu.be/hRsWi4HIENc

Introduction to RTOS Part 11 - https://youtu.be/C2xKhxROmhA

Introduction to RTOS Part 12 - https://youtu.be/LPSHUcH5aQc

Related Project Links:
https://www.digikey.com/en/maker/projects/introduction-to-rtos-solution-to-part-8-software-timers/0f64cf758da440a29476165a5b2e577e

Related Articles:
https://www.digikey.com/en/maker/videos/shawn-hymel/getting-started-with-stm32-and-nucleo-part-3-how-to-run-multiple-threads-with-cmsis-rtos-interface

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