Timers

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Detailed Description

In addition to time control over tasks the uSmartX kernel provides another way of time control via software timers. Each system tick software timers are evaluated. If one or more timers expires the tiemr associated call-back function is executed. the uSmartX kernel places timers in a so called relative time queue, where each timer expiration is relative to the preceeding timer. Timers that will expire at the same time have 0 relative ticks. In this way each system tick only one timer is evaluated. This increase performances drasticaly. Please note that the call-back function will be executed from uSMARTX_Tick() function context.

The call back function must be of type:

 STATUS my_callback_func(uint8, void*, void*)

Defines
#define	TMR_CREATE(name)
	Create a software timer.
#define	WAIT_FOREVER   0xFFFF
	Timeout period.
#define	NO_WAIT   0
	Timeout period.
#define	TMR_PERIODIC   1
	Software timer mode.
#define	TMR_ONE_SHOT   2
	Software timer mode.
Functions
void	TMR_Start (HANDLE *ph, uint16 tout, STATUS(*pfxn)(uint8, void *, void *), uint8 evt, void *parg1, void *parg2, uint8 mode)
	Timer start function.
void	TMR_ReStart (HANDLE *ph)
	Timer re-start function.
void	TMR_Stop (HANDLE *ph)
	Timer stop function.
uint32	TMR_GetTicks (void)
	Return system ticks.

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Define Documentation

#define NO_WAIT   0

Timeout period. When a system call timeout parameter has this value the system call won't wait the resource but will return immediately even if the resource isn't avaible.

#define TMR_CREATE (  name   )

Create a software timer. This macro creates a timer Examples: timers.c.

#define TMR_ONE_SHOT   2

Software timer mode. The started SW timer will run in one shot mode. Once the timeout will expire and the call-back function will be executed. The timer won't be restarted automaticaly. Examples: timers.c.

#define TMR_PERIODIC   1

Software timer mode. The started SW timer will run in periodic mode. Once the timeout will expire and the call-back function will be executed the task will be re-started again automaticaly.

#define WAIT_FOREVER   0xFFFF

Timeout period. When a system call's timeout parameter has this value the system call won't return until the resource will be avaible.

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Function Documentation

uint32 TMR_GetTicks (  void   )

Return system ticks. This function returns elapsed system ticks since system startup. Return values: elapsed  system ticks Examples: timers.c.

void TMR_ReStart (  HANDLE *  ph  )

Timer re-start function. This function re-starts a software timer. Be careful to apply this system call only on an already started timer. Its functionality is very similar to TMR_Start() function but it is faster. Parameters: ph  handle to timer

void TMR_Start (  HANDLE *  ph, uint16  tout, STATUS(*)(uint8, void *, void *)  pfxn, uint8  evt, void *  parg1, void *  parg2, uint8  mode )

Timer start function. This function starts a software timer. A valid call back function must be passed to the function. The timer is re-started if it was already started. Timers can be one shot or periodic. Parameters: ph  handle to timer tout  timeout value pfxn  address of the callback function evt  event to be passed to the call-back function parg1  argument 1 to be passed to the call-back function parg2  argument 2 to be passed to the call-back function mode  one-shot or periodic mode Attention: The callback function will be executed from the context where uSMARTX_Tick function was called. Examples: timers.c.

void TMR_Stop (  HANDLE *  ph  )

Timer stop function. This function stops a software timer without executin its call-back function. Parameters: ph  handle to timer

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