GTIMER

Detailed Description

Module which provides software based timers for user-space applications.

The reason why uGFX has it's own timer abstraction is because virtual timers provided by ChibiOS/RT are interrupt context only. While great for what they are designed for, they make coding of the input drivers much more complex. For non-performance critical drivers like these input drivers, it would also hog an in-ordinate amount of critical (interrupt locked) system time. This contrary to the goals of a real-time operating system. So a user-land (thread based) timer mechanism is also required.

Precondition

GFX_USE_GTIMER must be set to GFXON in your gfxconf.h

Data Structures
struct	GTimer_t
	A GTimer structure. More...

Functions
void	gtimerInit (GTimer *pt)
	Initialise a timer. More...
void	gtimerDeinit (GTimer *pt)
	Deinitialise a timer. More...
void	gtimerStart (GTimer *pt, GTimerFunction fn, void *param, gBool periodic, gDelay millisec)
	Set a timer going or alter its properties if it is already going. More...
void	gtimerStop (GTimer *pt)
	Stop a timer (periodic or otherwise) More...
gBool	gtimerIsActive (GTimer *pt)
	Test if a timer is currently active. More...
void	gtimerJab (GTimer *pt)
	Jab a timer causing the current period to immediate expire. More...
void	gtimerJabI (GTimer *pt)
	Jab a timer causing the current period to immediate expire. More...

GTIMER Optional Sizing Parameters
#define	GTIMER_THREAD_PRIORITY   gThreadpriorityHigh
	Defines the GTIMER thread priority. More...
#define	GTIMER_THREAD_WORKAREA_SIZE   2048
	Defines the size of the timer threads work area (stack+structures). More...

Typedefs
typedef struct GTimer_t	GTimer
	A GTimer structure. More...

Function Documentation

gtimerDeinit()

void gtimerDeinit

(

GTimer *

pt

)

Deinitialise a timer.

Parameters

[in]

pt

Pointer to a GTimer structure

Function Class: Normal API, this function can be invoked by regular system threads.

Definition at line 134 of file gtimer.c.

References gtimerStop().

gtimerInit()

void gtimerInit

(

GTimer *

pt

)

Initialise a timer.

Parameters

[in]

pt

Pointer to a GTimer structure

Function Class: Normal API, this function can be invoked by regular system threads.

Definition at line 129 of file gtimer.c.

gtimerIsActive()

gBool gtimerIsActive

(

GTimer *

pt

)

Test if a timer is currently active.

Parameters

[in]

pt

Pointer to a GTimer structure

Returns

gTrue if active, gFalse otherwise

Function Class: Normal API, this function can be invoked by regular system threads.

Definition at line 208 of file gtimer.c.

Referenced by ginputGetToggle().

gtimerJab()

void gtimerJab

(

GTimer *

pt

)

Jab a timer causing the current period to immediate expire.

The callback function will be called as soon as possible.

Precondition

Use from a normal thread context.

Parameters

[in]

pt

Pointer to a GTimer structure

Note

If the timer is not active this does nothing.

Repeated Jabs before the callback function actually happens are ignored.

Function Class: Normal API, this function can be invoked by regular system threads.

Definition at line 212 of file gtimer.c.

References gfxMutexEnter(), gfxMutexExit(), and gfxSemSignal().

gtimerJabI()

void gtimerJabI

(

GTimer *

pt

)

Jab a timer causing the current period to immediate expire.

The callback function will be called as soon as possible.

Precondition

Use from an interrupt routine context.

Parameters

[in]

pt

Pointer to a GTimer structure

Note

If the timer is not active this does nothing.

Repeated Jabs before the callback function actually happens are ignored.

Function Class: This is an I-Class API, this function can be invoked from within a system lock zone by both threads and interrupt handlers.

Function Class: Normal API, this function can be invoked by regular system threads.

Definition at line 223 of file gtimer.c.

References gfxSemSignalI().

gtimerStart()

void gtimerStart	(	GTimer *	pt,
		GTimerFunction	fn,
		void *	param,
		gBool	periodic,
		gDelay	millisec
	)

Set a timer going or alter its properties if it is already going.

Parameters

[in]	pt	Pointer to a GTimer structure
[in]	fn	The callback function
[in]	param	The parameter to pass to the callback function
[in]	periodic	Is the timer a periodic timer? gFalse is a once-only timer.
[in]	millisec	The timer period. The following special values are allowed: gDelayNone causes the callback function to be called asap. A periodic timer with this value will fire once only. gDelayForever never timeout (unless triggered by gtimerJab or gtimerJabI)

Note

If the timer is already active its properties are updated with the new parameters. The current period will be immediately canceled (without the callback function being called) and the timer will be restart with the new timer properties.

The callback function should be careful not to over-run the thread stack. Define a new value for the macro GTIME_THREAD_STACK_SIZE if you want to change the default size.

The callback function should return as quickly as possible as all timer callbacks are performed by a single thread. If a callback function takes too long it could affect the timer response for other timers.

A timer callback function is not a replacement for a dedicated thread if the function wants to perform computationally expensive stuff.

As the callback function is called on GTIMER's thread, the function must make sure it uses appropriate synchronisation controls such as semaphores or mutexes around any data structures it shares with other threads such as the main application thread.

Function Class: Normal API, this function can be invoked by regular system threads.

Definition at line 139 of file gtimer.c.

gtimerStop()

void gtimerStop

(

GTimer *

pt

)

Stop a timer (periodic or otherwise)

Parameters

[in]

pt

Pointer to a GTimer structure

Note

If the timer is not active this does nothing.

Function Class: Normal API, this function can be invoked by regular system threads.

Definition at line 190 of file gtimer.c.

References gfxMutexEnter(), and gfxMutexExit().

Referenced by gtimerDeinit().

Macro Definition Documentation

GTIMER_THREAD_PRIORITY

#define GTIMER_THREAD_PRIORITY   gThreadpriorityHigh

Defines the GTIMER thread priority.

Defaults to gThreadpriorityHigh

Definition at line 34 of file gtimer_options.h.

GTIMER_THREAD_WORKAREA_SIZE

#define GTIMER_THREAD_WORKAREA_SIZE   2048

Defines the size of the timer threads work area (stack+structures).

Defaults to 2048 bytes

Definition at line 41 of file gtimer_options.h.

Typedef Documentation

GTimer

typedef struct GTimer_t GTimer

A GTimer structure.