Application timer functionality. More...

Collaboration diagram for Application Timer:

Macros
#define	APP_TIMER_CLOCK_FREQ CLOCK_SECOND

#define	APP_TIMER_MIN_TIMEOUT_TICKS 1

#define	APP_TIMER_TICKS(MS, PRESCALER) MS_TO_TICKS(MS)
	Convert milliseconds to timer ticks. More...

#define	APP_TIMER_DEF(timer_id)
	Create a timer identifier and statically allocate memory for the timer. More...

#define	APP_TIMER_INIT(PRESCALER, OP_QUEUES_SIZE, SCHEDULER_FUNC)
	Initialize the application timer module. More...

Typedefs
typedef struct app_timer_t *	app_timer_id_t
	Timer ID type. Never declare a variable of this type, but use the macro APP_TIMER_DEF instead.

typedef void(*	app_timer_timeout_handler_t) (void *p_context)
	Application time-out handler type.

typedef uint32_t(*	app_timer_evt_schedule_func_t) (app_timer_timeout_handler_t timeout_handler, void *p_context)
	Type of function for passing events from the timer module to the scheduler.

Enumerations

Functions
uint32_t	app_timer_init (app_timer_evt_schedule_func_t evt_schedule_func)
	Function for initializing the timer module. More...

uint32_t	app_timer_create (app_timer_id_t const *p_timer_id, app_timer_mode_t mode, app_timer_timeout_handler_t timeout_handler)
	Function for creating a timer instance. More...

uint32_t	app_timer_start (app_timer_id_t timer_id, uint32_t timeout_ticks, void *p_context)
	Function for starting a timer. More...

uint32_t	app_timer_stop (app_timer_id_t timer_id)
	Function for stopping the specified timer. More...

uint32_t	app_timer_stop_all (void)
	Function for stopping all running timers. More...

uint32_t	app_timer_cnt_get (uint32_t *p_ticks)
	Function for returning the current value of the RTC1 counter. More...

uint32_t	app_timer_cnt_diff_compute (uint32_t ticks_to, uint32_t ticks_from, uint32_t *p_ticks_diff)
	Function for computing the difference between two RTC1 counter values. More...

Detailed Description

Application timer functionality.

This module enables the application to create multiple timer instances based on the RTC1 peripheral. Checking for time-outs and invokation of user time-out handlers is performed in the RTC1 interrupt handler. List handling is done using a software interrupt (SWI0). Both interrupt handlers are running in APP_LOW priority level.

When calling app_timer_start() or app_timer_stop(), the timer operation is just queued, and the software interrupt is triggered. The actual timer start/stop operation is executed by the SWI0 interrupt handler. Since the SWI0 interrupt is running in APP_LOW, if the application code calling the timer function is running in APP_LOW or APP_HIGH, the timer operation will not be performed until the application handler has returned. This will be the case, for example, when stopping a timer from a time-out handler when not using the scheduler.

Use the USE_SCHEDULER parameter of the APP_TIMER_INIT() macro to select if the app_scheduler should be used or not. Even if the scheduler is not used, app_timer.h will include app_scheduler.h, so when compiling, app_scheduler.h must be available in one of the compiler include paths.

Macro Definition Documentation

#define APP_TIMER_CLOCK_FREQ CLOCK_SECOND

Clock frequency of the RTC timer used to implement the app timer module.

Definition at line 52 of file app_timer.h.

#define APP_TIMER_MIN_TIMEOUT_TICKS 1

Minimum value of the timeout_ticks parameter of app_timer_start().

Definition at line 53 of file app_timer.h.

#define APP_TIMER_TICKS	(	MS,
		PRESCALER
	)	MS_TO_TICKS(MS)

Convert milliseconds to timer ticks.

This macro uses 64-bit integer arithmetic, but as long as the macro parameters are constants (i.e. defines), the computation will be done by the preprocessor.

When using this macro, ensure that the values provided as input result in an output value that is supported by the app_timer_start function. For example, when the ticks for 1 ms is needed, the maximum possible value of PRESCALER must be 6, when APP_TIMER_CLOCK_FREQ is 32768. This will result in a ticks value as 5. Any higher value for PRESCALER will result in a ticks value that is not supported by this module.

Parameters

[in]	MS	Milliseconds.
[in]	PRESCALER	Value of the RTC1 PRESCALER register (must be the same value that was passed to APP_TIMER_INIT()).

Returns: Number of timer ticks.

Definition at line 73 of file app_timer.h.

#define APP_TIMER_DEF ( timer_id )

Value:

static app_timer_t timer_id##_data = {                       \
      .work = MWORK_INIT(timer_id##_data.work, app_timer_work_cb),    \
      .mode = (app_timer_mode_t) -1,                             \
    };                                                           \
    static const app_timer_id_t timer_id = &timer_id##_data

Create a timer identifier and statically allocate memory for the timer.

Parameters

timer_id Name of the timer identifier variable that will be used to control the timer.

Definition at line 87 of file app_timer.h.

#define APP_TIMER_INIT	(	PRESCALER,
		OP_QUEUES_SIZE,
		SCHEDULER_FUNC
	)

Value:

do                                                                                             \
    {                                                                                              \
        uint32_t ERR_CODE = app_timer_init(SCHEDULER_FUNC);                                        \
        APP_ERROR_CHECK(ERR_CODE);                                                                 \
    } while (0)

Initialize the application timer module.

This macro handles dimensioning and allocation of the memory buffer required by the timer, making sure that the buffer is correctly aligned. It will also connect the timer module to the scheduler (if specified).

Note: This module assumes that the LFCLK is already running. If it is not, the module will be non-functional, since the RTC will not run. If you do not use a SoftDevice, you must start the LFCLK manually. See the rtc_example's lfclk_config() function for an example of how to do this. If you use a SoftDevice, the LFCLK is started on SoftDevice init.

Parameters

[in]	PRESCALER	Value of the RTC1 PRESCALER register. This will decide the timer tick rate. Set to 0 for no prescaling.
[in]	OP_QUEUES_SIZE	Size of queues holding timer operations that are pending execution.
[in]	SCHEDULER_FUNC	Pointer to scheduler event handler

Note: Since this macro allocates a buffer, it must only be called once (it is OK to call it several times as long as it is from the same location, for example, to do a re-initialization).

Definition at line 141 of file app_timer.h.

Enumeration Type Documentation

enum app_timer_mode_t

Timer modes.

Enumerator
APP_TIMER_MODE_SINGLE_SHOT	The timer will expire only once.
APP_TIMER_MODE_REPEATED	The timer will restart each time it expires.

Definition at line 103 of file app_timer.h.

Function Documentation

uint32_t app_timer_init ( app_timer_evt_schedule_func_t evt_schedule_func )

Function for initializing the timer module.

Normally, initialization should be done using the APP_TIMER_INIT() macro, because that macro will both allocate the buffers needed by the timer module (including aligning the buffers correctly) and take care of connecting the timer module to the scheduler (if specified).

Parameters

[in] evt_schedule_func Function for passing time-out events to the scheduler. Point to app_timer_evt_schedule() to connect to the scheduler. Set to NULL to make the timer module call the time-out handler directly from the timer interrupt handler.

Return values

NRF_SUCCESS	If the module was initialized successfully.
NRF_ERROR_INVALID_PARAM	If a parameter was invalid (buffer not aligned to a 4 byte boundary or NULL).

Definition at line 24 of file app_timer.c.

uint32_t app_timer_create	(	app_timer_id_t const *	p_timer_id,
		app_timer_mode_t	mode,
		app_timer_timeout_handler_t	timeout_handler
	)

Function for creating a timer instance.

Parameters

[in]	p_timer_id	Pointer to timer identifier.
[in]	mode	Timer mode.
[in]	timeout_handler	Function to be executed when the timer expires.

Return values

NRF_SUCCESS	If the timer was successfully created.
NRF_ERROR_INVALID_PARAM	If a parameter was invalid.
NRF_ERROR_INVALID_STATE	If the application timer module has not been initialized or the timer is running.

Note: This function does the timer allocation in the caller's context. It is also not protected by a critical region. Therefore care must be taken not to call it from several interrupt levels simultaneously.; The function can be called again on the timer instance and will re-initialize the instance if the timer is not running.

Attention: The FreeRTOS and RTX app_timer implementation does not allow app_timer_create to be called on the previously initialized instance.

Definition at line 30 of file app_timer.c.

uint32_t app_timer_start	(	app_timer_id_t	timer_id,
		uint32_t	timeout_ticks,
		void *	p_context
	)

Function for starting a timer.

Parameters

[in]	timer_id	Timer identifier.
[in]	timeout_ticks	Number of ticks (of RTC1, including prescaling) to time-out event (minimum 5 ticks).
[in]	p_context	General purpose pointer. Will be passed to the time-out handler when the timer expires.

Return values

NRF_SUCCESS	If the timer was successfully started.
NRF_ERROR_INVALID_PARAM	If a parameter was invalid.
NRF_ERROR_INVALID_STATE	If the application timer module has not been initialized or the timer has not been created.
NRF_ERROR_NO_MEM	If the timer operations queue was full.

Note: The minimum timeout_ticks value is 5.; For multiple active timers, time-outs occurring in close proximity to each other (in the range of 1 to 3 ticks) will have a positive jitter of maximum 3 ticks.; When calling this method on a timer that is already running, the second start operation is ignored.

Definition at line 43 of file app_timer.c.

References mwork_now(), mwork_schedule(), swint_disable(), and swint_enable().

uint32_t app_timer_stop ( app_timer_id_t timer_id )

Function for stopping the specified timer.

Parameters

[in] timer_id Timer identifier.

Return values

NRF_SUCCESS	If the timer was successfully stopped.
NRF_ERROR_INVALID_PARAM	If a parameter was invalid.
NRF_ERROR_INVALID_STATE	If the application timer module has not been initialized or the timer has not been created.
NRF_ERROR_NO_MEM	If the timer operations queue was full.

Definition at line 56 of file app_timer.c.

References mwork_cancel().

uint32_t app_timer_stop_all ( void )

Function for stopping all running timers.

Return values

NRF_SUCCESS	If all timers were successfully stopped.
NRF_ERROR_INVALID_STATE	If the application timer module has not been initialized.
NRF_ERROR_NO_MEM	If the timer operations queue was full.

uint32_t app_timer_cnt_get ( uint32_t * p_ticks )

Function for returning the current value of the RTC1 counter.

Parameters

[out] p_ticks Current value of the RTC1 counter.

Return values

NRF_SUCCESS If the counter was successfully read.

uint32_t app_timer_cnt_diff_compute	(	uint32_t	ticks_to,
		uint32_t	ticks_from,
		uint32_t *	p_ticks_diff
	)

Function for computing the difference between two RTC1 counter values.

Parameters

[in]	ticks_to	Value returned by app_timer_cnt_get().
[in]	ticks_from	Value returned by app_timer_cnt_get().
[out]	p_ticks_diff	Number of ticks from ticks_from to ticks_to.

Return values

NRF_SUCCESS If the counter difference was successfully computed.

Macros

Typedefs

Enumerations

Functions

Detailed Description

Macro Definition Documentation

Enumeration Type Documentation

Function Documentation