app_timer.h

00001 /* Copyright (c) 2012 Nordic Semiconductor. All Rights Reserved.
00002  *
00003  * The information contained herein is property of Nordic Semiconductor ASA.
00004  * Terms and conditions of usage are described in detail in NORDIC
00005  * SEMICONDUCTOR STANDARD SOFTWARE LICENSE AGREEMENT.
00006  *
00007  * Licensees are granted free, non-transferable use of the information. NO
00008  * WARRANTY of ANY KIND is provided. This heading must NOT be removed from
00009  * the file.
00010  *
00011  */
00012 
00013 /** @file
00014  *
00015  * @defgroup app_timer Application Timer
00016  * @{
00017  * @ingroup app_common
00018  *
00019  * @brief Application timer functionality.
00020  *
00021  * @details It enables the application to create multiple timer instances based on the RTC1
00022  *          peripheral. Checking for timeouts and invokation of user timeout handlers is performed
00023  *          in the RTC1 interrupt handler. List handling is done using a software interrupt (SWI0).
00024  *          Both interrupt handlers are running in APP_LOW priority level.
00025  *
00026  * @note    When calling app_timer_start() or app_timer_stop(), the timer operation is just queued,
00027  *          and the software interrupt is triggered. The actual timer start/stop operation is
00028  *          executed by the SWI0 interrupt handler. Since the SWI0 interrupt is running in APP_LOW,
00029  *          if the application code calling the timer function is running in APP_LOW or APP_HIGH,
00030  *          the timer operation will not be performed until the application handler has returned.
00031  *          This will be the case e.g. when stopping a timer from a timeout handler when not using
00032  *          the scheduler.
00033  *
00034  * @details Use the USE_SCHEDULER parameter of the APP_TIMER_INIT() macro to select if the
00035  *          @ref app_scheduler is to be used or not.
00036  *
00037  * @note    Even if the scheduler is not used, app_timer.h will include app_scheduler.h, so when
00038  *          compiling, app_scheduler.h must be available in one of the compiler include paths.
00039  */
00040 
00041 #ifndef APP_TIMER_H__
00042 #define APP_TIMER_H__
00043 
00044 #include <stdint.h>
00045 #include <stdbool.h>
00046 #include <stdio.h>
00047 #include "nordic_global.h"
00048 #include "app_error.h "
00049 #include "app_util.h "
00050 #include "app_scheduler.h "
00051 #include "compiler_abstraction.h"
00052 
00053 #define APP_TIMER_SCHED_EVT_SIZE     sizeof(app_timer_event_t)  /**< Size of button events being passed through the scheduler (is to be used for computing the maximum size of scheduler events). */
00054 #define APP_TIMER_CLOCK_FREQ         32768                      /**< Clock frequency of the RTC timer used to implement the app timer module. */
00055 #define APP_TIMER_MIN_TIMEOUT_TICKS  5                          /**< Minimum value of the timeout_ticks parameter of app_timer_start(). */
00056 
00057 #define APP_TIMER_NODE_SIZE          40                         /**< Size of app_timer.timer_node_t (only for use inside APP_TIMER_BUF_SIZE()). */
00058 #define APP_TIMER_USER_OP_SIZE       24                         /**< Size of app_timer.timer_user_op_t (only for use inside APP_TIMER_BUF_SIZE()). */
00059 #define APP_TIMER_USER_SIZE          8                          /**< Size of app_timer.timer_user_t (only for use inside APP_TIMER_BUF_SIZE()). */
00060 #define APP_TIMER_INT_LEVELS         3                          /**< Number of interrupt levels from where timer operations may be initiated (only for use inside APP_TIMER_BUF_SIZE()). */
00061 
00062 /**@brief Compute number of bytes required to hold the application timer data structures.
00063  *
00064  * @param[in]  MAX_TIMERS      Maximum number of timers that can be created at any given time.
00065  * @param[in]  OP_QUEUE_SIZE   Size of queues holding timer operations that are pending execution.
00066  *                             NOTE: Due to the queue implementation, this size must be one more
00067  *                             than the size that is actually needed.
00068  *
00069  * @return     Required application timer buffer size (in bytes).
00070  */
00071 #define APP_TIMER_BUF_SIZE(MAX_TIMERS, OP_QUEUE_SIZE)                                              \
00072     (                                                                                              \
00073         ((MAX_TIMERS) * APP_TIMER_NODE_SIZE)                                                       \
00074         +                                                                                          \
00075         (                                                                                          \
00076             APP_TIMER_INT_LEVELS                                                                   \
00077             *                                                                                      \
00078             (APP_TIMER_USER_SIZE + ((OP_QUEUE_SIZE) + 1) * APP_TIMER_USER_OP_SIZE)                 \
00079         )                                                                                          \
00080     )
00081 
00082 /**@brief Convert milliseconds to timer ticks.
00083  *
00084  * @note This macro uses 64 bit integer arithmetic, but as long as the macro parameters are
00085  *       constants (i.e. defines), the computation will be done by the preprocessor.
00086  *
00087  * @param[in]  MS          Milliseconds.
00088  * @param[in]  PRESCALER   Value of the RTC1 PRESCALER register (must be the same value that was
00089  *                         passed to APP_TIMER_INIT()). 
00090  * 
00091  * @note   When using this macro, it is the responsibility of the developer to ensure that the 
00092  *         values provided as input result in an output value that is supported by the
00093  *         @ref app_timer_start function. For example, when the ticks for 1 ms is needed, the
00094  *         maximum possible value of PRESCALER must be 6, when @ref APP_TIMER_CLOCK_FREQ is 32768.
00095  *         This will result in a ticks value as 5. Any higher value for PRESCALER will result in a
00096  *         ticks value that is not supported by this module.
00097  *
00098  * @return     Number of timer ticks.
00099  */
00100 #define APP_TIMER_TICKS(MS, PRESCALER)\
00101             ((uint32_t)ROUNDED_DIV((MS) * (uint64_t)APP_TIMER_CLOCK_FREQ, ((PRESCALER) + 1) * 1000))
00102 
00103 /**@brief Timer id type. */
00104 typedef uint32_t app_timer_id_t;
00105 
00106 /**@brief Application timeout handler type. */
00107 typedef void (*app_timer_timeout_handler_t)(void * p_context);
00108 
00109 /**@brief Type of function for passing events from the timer module to the scheduler. */
00110 typedef uint32_t (*app_timer_evt_schedule_func_t) (app_timer_timeout_handler_t timeout_handler,
00111                                                    void *                      p_context);
00112 
00113 /**@brief Timer modes. */
00114 typedef enum
00115 {
00116     APP_TIMER_MODE_SINGLE_SHOT,                 /**< The timer will expire only once. */
00117     APP_TIMER_MODE_REPEATED                     /**< The timer will restart each time it expires. */
00118 } app_timer_mode_t;
00119 
00120 /**@brief Macro for initializing the application timer module.
00121  *
00122  * @details It will handle dimensioning and allocation of the memory buffer required by the timer,
00123  *          making sure that the buffer is correctly aligned. It will also connect the timer module
00124  *          to the scheduler (if specified).
00125  *
00126  * @param[in]  PRESCALER        Value of the RTC1 PRESCALER register. This will decide the
00127  *                              timer tick rate. Set to 0 for no prescaling.
00128  * @param[in]  MAX_TIMERS       Maximum number of timers that can be created at any given time.
00129  * @param[in]  OP_QUEUES_SIZE   Size of queues holding timer operations that are pending execution.
00130  * @param[in]  USE_SCHEDULER    TRUE if the application is using the event scheduler,
00131  *                              FALSE otherwise.
00132  *
00133  * @note Since this macro allocates a buffer, it must only be called once (it is OK to call it
00134  *       several times as long as it is from the same location, e.g. to do a reinitialization).
00135  */
00136 /*lint -emacro(506, APP_TIMER_INIT) */ /* Suppress "Constant value Boolean */
00137 #define APP_TIMER_INIT(PRESCALER, MAX_TIMERS, OP_QUEUES_SIZE, USE_SCHEDULER)                       \
00138     do                                                                                             \
00139     {                                                                                              \
00140         static uint32_t APP_TIMER_BUF[CEIL_DIV(APP_TIMER_BUF_SIZE((MAX_TIMERS),                    \
00141                                                                   (OP_QUEUES_SIZE) + 1),           \
00142                                                sizeof(uint32_t))];                                 \
00143         uint32_t ERR_CODE = app_timer_init((PRESCALER),                                            \
00144                                            (MAX_TIMERS),                                           \
00145                                            (OP_QUEUES_SIZE) + 1,                                   \
00146                                            APP_TIMER_BUF,                                          \
00147                                            (USE_SCHEDULER) ? app_timer_evt_schedule : NULL);       \
00148         APP_ERROR_CHECK(ERR_CODE);                                                                 \
00149     } while (0)
00150 
00151 /**@brief Function for initializing the timer module.
00152  *
00153  * @note Normally initialization should be done using the APP_TIMER_INIT() macro, as that will both
00154  *       allocate the buffers needed by the timer module (including aligning the buffers correctly,
00155  *       and also take care of connecting the timer module to the scheduler (if specified).
00156  *
00157  * @param[in]  prescaler           Value of the RTC1 PRESCALER register. Set to 0 for no prescaling.
00158  * @param[in]  max_timers          Maximum number of timers that can be created at any given time.
00159  * @param[in]  op_queues_size      Size of queues holding timer operations that are pending
00160  *                                 execution. NOTE: Due to the queue implementation, this size must
00161  *                                 be one more than the size that is actually needed.
00162  * @param[in]  p_buffer            Pointer to memory buffer for internal use in the app_timer
00163  *                                 module. The size of the buffer can be computed using the
00164  *                                 APP_TIMER_BUF_SIZE() macro. The buffer must be aligned to a
00165  *                                 4 byte boundary.
00166  * @param[in]  evt_schedule_func   Function for passing timeout events to the scheduler. Point to
00167  *                                 app_timer_evt_schedule() to connect to the scheduler. Set to NULL
00168  *                                 to make the timer module call the timeout handler directly from
00169  *                                 the timer interrupt handler.
00170  *
00171  * @retval     NRF_SUCCESS               Successful initialization.
00172  * @retval     NRF_ERROR_INVALID_PARAM   Invalid parameter (buffer not aligned to a 4 byte
00173  *                                       boundary or NULL).
00174  */
00175 uint32_t app_timer_init(uint32_t                      prescaler, 
00176                         uint8_t                       max_timers,
00177                         uint8_t                       op_queues_size,
00178                         void *                        p_buffer,
00179                         app_timer_evt_schedule_func_t evt_schedule_func);
00180 
00181 /**@brief Function for creating a timer instance.
00182  *
00183  * @param[out] p_timer_id        Id of the newly created timer.
00184  * @param[in]  mode              Timer mode.
00185  * @param[in]  timeout_handler   Function to be executed when the timer expires.
00186  *
00187  * @retval     NRF_SUCCESS               Timer was successfully created.
00188  * @retval     NRF_ERROR_INVALID_PARAM   Invalid parameter.
00189  * @retval     NRF_ERROR_INVALID_STATE   Application timer module has not been initialized.
00190  * @retval     NRF_ERROR_NO_MEM          Maximum number of timers has already been reached.
00191  *
00192  * @note This function does the timer allocation in the caller's context. It is also not protected
00193  *       by a critical region. Therefore care must be taken not to call it from several interrupt
00194  *       levels simultaneously.
00195  */
00196 uint32_t app_timer_create(app_timer_id_t *            p_timer_id,
00197                           app_timer_mode_t            mode,
00198                           app_timer_timeout_handler_t timeout_handler);
00199 
00200 /**@brief Function for starting a timer.
00201  *
00202  * @param[in]  timer_id        Id of timer to start.
00203  * @param[in]  timeout_ticks   Number of ticks (of RTC1, including prescaling) to timeout event
00204  *                             (minimum 5 ticks).
00205  * @param[in]  p_context       General purpose pointer. Will be passed to the timeout handler when
00206  *                             the timer expires.
00207  *
00208  * @retval     NRF_SUCCESS               Timer was successfully started.
00209  * @retval     NRF_ERROR_INVALID_PARAM   Invalid parameter.
00210  * @retval     NRF_ERROR_INVALID_STATE   Application timer module has not been initialized, or timer
00211  *                                       has not been created.
00212  * @retval     NRF_ERROR_NO_MEM          Timer operations queue was full.
00213  *
00214  * @note The minimum timeout_ticks value is 5.
00215  * @note For multiple active timers, timeouts occurring in close proximity to each other (in the
00216  *       range of 1 to 3 ticks) will have a positive jitter of maximum 3 ticks.
00217  * @note When calling this method on a timer which is already running, the second start operation
00218  *       will be ignored.
00219  */
00220 uint32_t app_timer_start(app_timer_id_t timer_id, uint32_t timeout_ticks, void * p_context);
00221 
00222 /**@brief Function for stopping the specified timer.
00223  *
00224  * @param[in]  timer_id   Id of timer to stop.
00225  *
00226  * @retval     NRF_SUCCESS               Timer was successfully stopped.
00227  * @retval     NRF_ERROR_INVALID_PARAM   Invalid parameter.
00228  * @retval     NRF_ERROR_INVALID_STATE   Application timer module has not been initialized, or timer
00229  *                                       has not been created.
00230  * @retval     NRF_ERROR_NO_MEM          Timer operations queue was full.
00231  */
00232 uint32_t app_timer_stop(app_timer_id_t timer_id);
00233 
00234 /**@brief Function for stopping all running timers.
00235  *
00236  * @retval     NRF_SUCCESS               All timers were successfully stopped.
00237  * @retval     NRF_ERROR_INVALID_STATE   Application timer module has not been initialized.
00238  * @retval     NRF_ERROR_NO_MEM          Timer operations queue was full.
00239  */
00240 uint32_t app_timer_stop_all(void);
00241 
00242 /**@brief Function for returning the current value of the RTC1 counter.
00243  *
00244  * @param[out] p_ticks   Current value of the RTC1 counter.
00245  *
00246  * @retval     NRF_SUCCESS   Counter was successfully read.
00247  */
00248 uint32_t app_timer_cnt_get(uint32_t * p_ticks);
00249 
00250 /**@brief Function for computing the difference between two RTC1 counter values.
00251  *
00252  * @param[in]  ticks_to       Value returned by app_timer_cnt_get().
00253  * @param[in]  ticks_from     Value returned by app_timer_cnt_get().
00254  * @param[out] p_ticks_diff   Number of ticks from ticks_from to ticks_to.
00255  *
00256  * @retval     NRF_SUCCESS   Counter difference was successfully computed.
00257  */
00258 uint32_t app_timer_cnt_diff_compute(uint32_t   ticks_to,
00259                                     uint32_t   ticks_from,
00260                                     uint32_t * p_ticks_diff);
00261 
00262 
00263 // Type and functions for connecting the timer to the scheduler:
00264 
00265 /**@cond NO_DOXYGEN */
00266 typedef struct
00267 {
00268     app_timer_timeout_handler_t timeout_handler;
00269     void *                      p_context;
00270 } app_timer_event_t;
00271 
00272 static __INLINE void app_timer_evt_get(void * p_event_data, uint16_t event_size)
00273 {
00274     app_timer_event_t * p_timer_event = (app_timer_event_t *)p_event_data;
00275     
00276     APP_ERROR_CHECK_BOOL(event_size == sizeof(app_timer_event_t));
00277     p_timer_event->timeout_handler(p_timer_event->p_context);
00278 }
00279 
00280 static __INLINE uint32_t app_timer_evt_schedule(app_timer_timeout_handler_t timeout_handler,
00281                                                 void *                      p_context)
00282 {
00283     app_timer_event_t timer_event;
00284 
00285     timer_event.timeout_handler = timeout_handler;
00286     timer_event.p_context       = p_context;
00287     
00288     return app_sched_event_put(&timer_event, sizeof(timer_event), app_timer_evt_get);
00289 }
00290 /**@endcond */
00291 
00292 #endif // APP_TIMER_H__
00293 
00294 /** @} */