TIMER¶

Timer

The timer is an integrated function of the microcontroller, which can be flexibly controlled by programming. The timing function of the microcontroller depends on the internal counter. Whenever the microcontroller experiences a machine cycle and generates a pulse, the counter will increase. The main function of the timer is to time. When the set time is reached, it will trigger an interrupt to notify the system that the timing is complete. In the interrupt service function, we can write specific programs to achieve the desired function.

What can a timer do

• Execute scheduled tasks: Timers are often used to periodically execute specific tasks. For example, if a task needs to be executed every 500 milliseconds, the timer can accurately meet this requirement.

• Time measurement: The timer can accurately measure time, whether it is the execution time of a code segment or the interval time of an event, it can be accurately measured by the timer.

• Accurate delay: For delay scenarios that require microsecond accuracy, the timer can provide a reliable solution to ensure the accuracy of the delay.

• PWN signal generation: Through the precise control of the timer, we can generate PWM (pulse width modulation) signals, which is crucial for applications such as driving motors and adjusting LED brightness.

• Event triggering and monitoring: The timer is not only used to trigger interrupts and implement event-driven logic, but also to implement watchdog functions, monitor system status, and perform reset operations when necessary to ensure stable operation of the system.

Types of Timers

Timers can be implemented either in hardware or software, each with its unique characteristics suited for different scenarios:

Hardware Timers rely on the built-in hardware mechanisms of microcontrollers, utilizing dedicated timing/counter circuits to achieve timing functionality. Their key advantages are high precision and reliability because hardware timers operate independently of software tasks and operating system scheduling, remaining unaffected by them. In scenarios demanding extremely high timing accuracy, such as generating PWM signals or performing precise time measurements, hardware timers are undoubtedly the best choice. Their design ensures that even if the main CPU is occupied with other tasks, the timer can still accurately trigger the designated operation at the preset time.

Software Timers, on the other hand, simulate timing functionality through the operating system or software libraries. The performance of these timers is affected by the system's current load and task scheduling strategies, resulting in slightly lower precision compared to hardware timers. However, software timers excel in flexibility, allowing the creation of numerous timers, making them ideal for scenarios where strict timing control is not required. It is important to note that software timers may encounter timing accuracy issues, especially under heavy system loads or when there are many high-priority tasks. Nevertheless, for simple delays where high precision is not critical, software timers are typically sufficient to meet the requirements.