S5PV210 Timer

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S5PV210 Timer [Copy link]

There are 4 types of timing devices in S5PV210, with different functions and features.

1. PWM timer
(1) This is the most commonly used timer. The timer we usually refer to is this one. The timer in a simple microcontroller (such as the 51 microcontroller) is also of this type.
(2) Why is it called a PWM timer? Because the PWM signal generated in a SoC is usually generated by this timer module.
2. System timer
(1) System (referring to the operating system) timer. The system timer is also used to generate a fixed time interval (TCNT × clock cycle) signal, called a systick. This systick is used to provide a tick signal to the operating system.
(2) Systick is generated as the time slice of the operating system. It is generally used in the scheduling system of the operating system to switch between processes in the scheduling system.
(3) When porting an operating system, we will not do this by ourselves. The basic porting part provided by the original manufacturer is usually included, so there is no need to study it here.
3. Watchdog timer
(1) The watchdog timer is essentially a timer, and there is no essential difference from the above two.
(2) The watchdog timer can be set to generate an interrupt when the time is up, or it can choose to send a reset signal to reset the CPU.
(3) Watchdog timers are widely used in practice, especially in the industrial field (complex environment, many interferences) where machines are prone to problems and the consequences are very serious. In this case, watchdogs are generally used to reset the system.
4. Real-time clock (RTC)
(1) Distinguish between time periods and time points. Time periods are relative. Subtracting two time points will give a time period; while time points are absolute and are unique.
(2) Timers focus on time periods (not time points). Timer timing starts from the moment the timer is turned on and an interrupt is generated when the specified time period ends; RTC uses time points (xx year x month x day x hour x minute x second week x).
(3) The difference between RTC and timers is equivalent to the difference between clocks and alarm clocks.