Application timer functionality.
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Application timer functionality.
This module enables the application to create multiple timer instances based on the RTC1 peripheral. Checking for time-outs and invocation 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 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.
| #define _APP_TIMER_DEF |
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timer_id | ) |
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| #define APP_TIMER_CLOCK_FREQ 32768 |
Clock frequency of the RTC timer used to implement the app timer module.
| #define APP_TIMER_DEF |
( |
|
timer_id | ) |
_APP_TIMER_DEF(timer_id) |
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. |
| #define APP_TIMER_MAX_CNT_VAL RTC_COUNTER_COUNTER_Msk |
| #define APP_TIMER_MIN_TIMEOUT_TICKS 5 |
| #define APP_TIMER_NODE_SIZE 32 |
Size of app_timer.timer_node_t (used to allocate data).
Size of event data when scheduler is used.
| #define APP_TIMER_TICKS |
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|
MS | ) |
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Value:
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.
- Parameters
-
- Returns
- Number of timer ticks.
Timer modes.
| Enumerator |
|---|
| APP_TIMER_MODE_SINGLE_SHOT |
The timer will expire only once.
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| APP_TIMER_MODE_REPEATED |
The timer will restart each time it expires.
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| uint32_t app_timer_cnt_diff_compute |
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uint32_t |
ticks_to, |
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uint32_t |
ticks_from |
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) |
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Function for computing the difference between two RTC1 counter values.
- Parameters
-
- Returns
- Number of ticks from ticks_from to ticks_to.
| uint32_t app_timer_cnt_get |
( |
void |
| ) |
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Function for returning the current value of the RTC1 counter.
- Returns
- Current value of the RTC1 counter.
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.
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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.
Function for initializing the timer module.
- Return values
-
| NRF_SUCCESS | If the module was initialized successfully. |
| uint8_t app_timer_op_queue_utilization_get |
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void |
| ) |
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Function for getting the maximum observed operation queue utilization.
Function for tuning the module and determining OP_QUEUE_SIZE value and thus module RAM usage.
- Note
- APP_TIMER_WITH_PROFILER must be enabled to use this functionality.
- Returns
- Maximum number of events in queue observed so far.
| void app_timer_pause |
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void |
| ) |
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Function for pausing RTC activity which drives app_timer.
- Note
- This function can be used for debugging purposes to ensure that application is halted when entering a breakpoint.
| void app_timer_resume |
( |
void |
| ) |
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Function for resuming RTC activity which drives app_timer.
- Note
- This function can be used for debugging purposes to resume application activity.
Function for starting a timer.
- Parameters
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| [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
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| 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.
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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.
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When calling this method on a timer that is already running, the second start operation is ignored.
Function for stopping the specified timer.
- Parameters
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| [in] | timer_id | Timer identifier. |
- Return values
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| 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. |
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. |