app_timer.h

00001 /*
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00032 
00033 /** @file
00034  *
00035  * @defgroup app_timer Application Timer
00036  * @{
00037  * @ingroup app_common
00038  *
00039  * @brief Application timer functionality.
00040  *
00041  * @details This module enables the application to create multiple timer instances based on the RTC1
00042  *          peripheral. Checking for time-outs and invokation of user time-out handlers is performed
00043  *          in the RTC1 interrupt handler. List handling is done using a software interrupt (SWI0).
00044  *          Both interrupt handlers are running in APP_LOW priority level.
00045  *
00046  * @details When calling app_timer_start() or app_timer_stop(), the timer operation is just queued,
00047  *          and the software interrupt is triggered. The actual timer start/stop operation is
00048  *          executed by the SWI0 interrupt handler. Since the SWI0 interrupt is running in APP_LOW,
00049  *          if the application code calling the timer function is running in APP_LOW or APP_HIGH,
00050  *          the timer operation will not be performed until the application handler has returned.
00051  *          This will be the case, for example, when stopping a timer from a time-out handler when not using
00052  *          the scheduler.
00053  *
00054  * @details Use the USE_SCHEDULER parameter of the APP_TIMER_INIT() macro to select if the
00055  *          @ref app_scheduler should be used or not. Even if the scheduler is 
00056  *          not used, app_timer.h will include app_scheduler.h, so when
00057  *          compiling, app_scheduler.h must be available in one of the compiler include paths.
00058  */
00059 
00060 #ifndef APP_TIMER_H__
00061 #define APP_TIMER_H__
00062 
00063 #include <stdint.h>
00064 #include <stdbool.h>
00065 #include <stdio.h>
00066 #include "app_error.h "
00067 #include "app_util.h "
00068 #include "compiler_abstraction.h"
00069 
00070 #define APP_TIMER_CLOCK_FREQ         32768                      /**< Clock frequency of the RTC timer used to implement the app timer module. */
00071 #define APP_TIMER_MIN_TIMEOUT_TICKS  5                          /**< Minimum value of the timeout_ticks parameter of app_timer_start(). */
00072 
00073 #define APP_TIMER_NODE_SIZE          32                         /**< Size of app_timer.timer_node_t (used to allocate data). */
00074 #define APP_TIMER_USER_OP_SIZE       24                         /**< Size of app_timer.timer_user_op_t (only for use inside APP_TIMER_BUF_SIZE()). */
00075 #define APP_TIMER_USER_SIZE          8                          /**< Size of app_timer.timer_user_t (only for use inside APP_TIMER_BUF_SIZE()). */
00076 #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()). */
00077 
00078 /**@brief Compute number of bytes required to hold the application timer data structures.
00079  *
00080  * @param[in]  OP_QUEUE_SIZE   Size of queues holding timer operations that are pending execution.
00081  *                             Note that due to the queue implementation, this size must be one more
00082  *                             than the size that is actually needed.
00083  *
00084  * @return     Required application timer buffer size (in bytes).
00085  */
00086 #define APP_TIMER_BUF_SIZE(OP_QUEUE_SIZE)                                              \
00087     (                                                                                              \
00088         (                                                                                          \
00089             APP_TIMER_INT_LEVELS                                                                   \
00090             *                                                                                      \
00091             (APP_TIMER_USER_SIZE + ((OP_QUEUE_SIZE) + 1) * APP_TIMER_USER_OP_SIZE)                 \
00092         )                                                                                          \
00093     )
00094 
00095 /**@brief Convert milliseconds to timer ticks.
00096  *
00097  * This macro uses 64-bit integer arithmetic, but as long as the macro parameters are
00098  *       constants (i.e. defines), the computation will be done by the preprocessor.
00099  * 
00100  * When using this macro, ensure that the 
00101  *         values provided as input result in an output value that is supported by the
00102  *         @ref app_timer_start function. For example, when the ticks for 1 ms is needed, the
00103  *         maximum possible value of PRESCALER must be 6, when @ref APP_TIMER_CLOCK_FREQ is 32768.
00104  *         This will result in a ticks value as 5. Any higher value for PRESCALER will result in a
00105  *         ticks value that is not supported by this module.
00106  *
00107  * @param[in]  MS          Milliseconds.
00108  * @param[in]  PRESCALER   Value of the RTC1 PRESCALER register (must be the same value that was
00109  *                         passed to APP_TIMER_INIT()). 
00110  *
00111  * @return     Number of timer ticks.
00112  */
00113 #define APP_TIMER_TICKS(MS, PRESCALER)\
00114             ((uint32_t)ROUNDED_DIV((MS) * (uint64_t)APP_TIMER_CLOCK_FREQ, ((PRESCALER) + 1) * 1000))
00115 
00116 typedef struct app_timer_t { uint32_t data[CEIL_DIV(APP_TIMER_NODE_SIZE, sizeof(uint32_t))]; } app_timer_t;
00117 
00118 /**@brief Timer ID type.
00119  * Never declare a variable of this type, but use the macro @ref APP_TIMER_DEF instead.*/
00120 typedef app_timer_t * app_timer_id_t;
00121 
00122 /**
00123  * @brief Create a timer identifier and statically allocate memory for the timer.
00124  *
00125  * @param timer_id Name of the timer identifier variable that will be used to control the timer.
00126  */
00127 #define APP_TIMER_DEF(timer_id)                                  \
00128     static app_timer_t timer_id##_data = { {0} };                  \
00129     static const app_timer_id_t timer_id = &timer_id##_data
00130 
00131 
00132 /**@brief Application time-out handler type. */
00133 typedef void (*app_timer_timeout_handler_t)(void * p_context);
00134 
00135 /**@brief Type of function for passing events from the timer module to the scheduler. */
00136 typedef uint32_t (*app_timer_evt_schedule_func_t) (app_timer_timeout_handler_t timeout_handler,
00137                                                    void *                      p_context);
00138 
00139 /**@brief Timer modes. */
00140 typedef enum
00141 {
00142     APP_TIMER_MODE_SINGLE_SHOT,                 /**< The timer will expire only once. */
00143     APP_TIMER_MODE_REPEATED                     /**< The timer will restart each time it expires. */
00144 } app_timer_mode_t;
00145 
00146 /**@brief Initialize the application timer module.
00147  *
00148  * @details This macro handles dimensioning and allocation of the memory buffer required by the timer,
00149  *          making sure that the buffer is correctly aligned. It will also connect the timer module
00150  *          to the scheduler (if specified).
00151  *
00152  * @note    This module assumes that the LFCLK is already running. If it is not, the module will 
00153  *          be non-functional, since the RTC will not run. If you do not use a SoftDevice, you 
00154  *          must start the LFCLK manually. See the rtc_example's lfclk_config() function 
00155  *          for an example of how to do this. If you use a SoftDevice, the LFCLK is started on 
00156  *          SoftDevice init. 
00157  *
00158  *
00159  * @param[in]  PRESCALER        Value of the RTC1 PRESCALER register. This will decide the
00160  *                              timer tick rate. Set to 0 for no prescaling.
00161  * @param[in]  OP_QUEUES_SIZE   Size of queues holding timer operations that are pending execution.
00162  * @param[in]  SCHEDULER_FUNC   Pointer to scheduler event handler
00163  *
00164  * @note Since this macro allocates a buffer, it must only be called once (it is OK to call it
00165  *       several times as long as it is from the same location, for example, to do a re-initialization).
00166  */
00167 /*lint -emacro(506, APP_TIMER_INIT) */ /* Suppress "Constant value Boolean */
00168 #define APP_TIMER_INIT(PRESCALER, OP_QUEUES_SIZE, SCHEDULER_FUNC)                                  \
00169     do                                                                                             \
00170     {                                                                                              \
00171         static uint32_t APP_TIMER_BUF[CEIL_DIV(APP_TIMER_BUF_SIZE((OP_QUEUES_SIZE) + 1),           \
00172                                                sizeof(uint32_t))];                                 \
00173         uint32_t ERR_CODE = app_timer_init((PRESCALER),                                            \
00174                                            (OP_QUEUES_SIZE) + 1,                                   \
00175                                            APP_TIMER_BUF,                                          \
00176                                            SCHEDULER_FUNC);                                        \
00177         APP_ERROR_CHECK(ERR_CODE);                                                                 \
00178     } while (0)
00179 
00180 
00181 
00182 /**@brief Function for initializing the timer module.
00183  *
00184  * Normally, initialization should be done using the APP_TIMER_INIT() macro, because that macro will both
00185  *       allocate the buffers needed by the timer module (including aligning the buffers correctly)
00186  *       and take care of connecting the timer module to the scheduler (if specified).
00187  *
00188  * @param[in]  prescaler           Value of the RTC1 PRESCALER register. Set to 0 for no prescaling.
00189  * @param[in]  op_queues_size      Size of queues holding timer operations that are pending
00190  *                                 execution. Note that due to the queue implementation, this size must
00191  *                                 be one more than the size that is actually needed.
00192  * @param[in]  p_buffer            Pointer to memory buffer for internal use in the app_timer
00193  *                                 module. The size of the buffer can be computed using the
00194  *                                 APP_TIMER_BUF_SIZE() macro. The buffer must be aligned to a
00195  *                                 4 byte boundary.
00196  * @param[in]  evt_schedule_func   Function for passing time-out events to the scheduler. Point to
00197  *                                 app_timer_evt_schedule() to connect to the scheduler. Set to NULL
00198  *                                 to make the timer module call the time-out handler directly from
00199  *                                 the timer interrupt handler.
00200  *
00201  * @retval     NRF_SUCCESS               If the module was initialized successfully.
00202  * @retval     NRF_ERROR_INVALID_PARAM   If a parameter was invalid (buffer not aligned to a 4 byte
00203  *                                       boundary or NULL).
00204  */
00205 uint32_t app_timer_init(uint32_t                      prescaler, 
00206                         uint8_t                       op_queues_size,
00207                         void *                        p_buffer,
00208                         app_timer_evt_schedule_func_t evt_schedule_func);
00209 
00210 /**@brief Function for creating a timer instance.
00211  *
00212  * @param[in]  p_timer_id        Pointer to timer identifier.
00213  * @param[in]  mode              Timer mode.
00214  * @param[in]  timeout_handler   Function to be executed when the timer expires.
00215  *
00216  * @retval     NRF_SUCCESS               If the timer was successfully created.
00217  * @retval     NRF_ERROR_INVALID_PARAM   If a parameter was invalid.
00218  * @retval     NRF_ERROR_INVALID_STATE   If the application timer module has not been initialized or
00219  *                                       the timer is running.
00220  *
00221  * @note This function does the timer allocation in the caller's context. It is also not protected
00222  *       by a critical region. Therefore care must be taken not to call it from several interrupt
00223  *       levels simultaneously.
00224  * @note The function can be called again on the timer instance and will re-initialize the instance if
00225  *       the timer is not running.
00226  * @attention The FreeRTOS and RTX app_timer implementation does not allow app_timer_create to
00227  *       be called on the previously initialized instance.
00228  */
00229 uint32_t app_timer_create(app_timer_id_t const *      p_timer_id,
00230                           app_timer_mode_t            mode,
00231                           app_timer_timeout_handler_t timeout_handler);
00232 
00233 /**@brief Function for starting a timer.
00234  *
00235  * @param[in]       timer_id      Timer identifier.
00236  * @param[in]       timeout_ticks Number of ticks (of RTC1, including prescaling) to time-out event
00237  *                                (minimum 5 ticks).
00238  * @param[in]       p_context     General purpose pointer. Will be passed to the time-out handler when
00239  *                                the timer expires.
00240  *
00241  * @retval     NRF_SUCCESS               If the timer was successfully started.
00242  * @retval     NRF_ERROR_INVALID_PARAM   If a parameter was invalid.
00243  * @retval     NRF_ERROR_INVALID_STATE   If the application timer module has not been initialized or the timer
00244  *                                       has not been created.
00245  * @retval     NRF_ERROR_NO_MEM          If the timer operations queue was full.
00246  *
00247  * @note The minimum timeout_ticks value is 5.
00248  * @note For multiple active timers, time-outs occurring in close proximity to each other (in the
00249  *       range of 1 to 3 ticks) will have a positive jitter of maximum 3 ticks.
00250  * @note When calling this method on a timer that is already running, the second start operation
00251  *       is ignored.
00252  */
00253 uint32_t app_timer_start(app_timer_id_t timer_id, uint32_t timeout_ticks, void * p_context);
00254 
00255 /**@brief Function for stopping the specified timer.
00256  *
00257  * @param[in]  timer_id                  Timer identifier.
00258  *
00259  * @retval     NRF_SUCCESS               If the timer was successfully stopped.
00260  * @retval     NRF_ERROR_INVALID_PARAM   If a parameter was invalid.
00261  * @retval     NRF_ERROR_INVALID_STATE   If the application timer module has not been initialized or the timer
00262  *                                       has not been created.
00263  * @retval     NRF_ERROR_NO_MEM          If the timer operations queue was full.
00264  */
00265 uint32_t app_timer_stop(app_timer_id_t timer_id);
00266 
00267 /**@brief Function for stopping all running timers.
00268  *
00269  * @retval     NRF_SUCCESS               If all timers were successfully stopped.
00270  * @retval     NRF_ERROR_INVALID_STATE   If the application timer module has not been initialized.
00271  * @retval     NRF_ERROR_NO_MEM          If the timer operations queue was full.
00272  */
00273 uint32_t app_timer_stop_all(void);
00274 
00275 /**@brief Function for returning the current value of the RTC1 counter.
00276  *
00277  * @param[out] p_ticks   Current value of the RTC1 counter.
00278  *
00279  * @retval     NRF_SUCCESS   If the counter was successfully read.
00280  */
00281 uint32_t app_timer_cnt_get(uint32_t * p_ticks);
00282 
00283 /**@brief Function for computing the difference between two RTC1 counter values.
00284  *
00285  * @param[in]  ticks_to       Value returned by app_timer_cnt_get().
00286  * @param[in]  ticks_from     Value returned by app_timer_cnt_get().
00287  * @param[out] p_ticks_diff   Number of ticks from ticks_from to ticks_to.
00288  *
00289  * @retval     NRF_SUCCESS   If the counter difference was successfully computed.
00290  */
00291 uint32_t app_timer_cnt_diff_compute(uint32_t   ticks_to,
00292                                     uint32_t   ticks_from,
00293                                     uint32_t * p_ticks_diff);
00294 
00295 #endif // APP_TIMER_H__
00296 
00297 /** @} */