Nordic stack and drivers for the mbed BLE API

Dependents:   BLE_ANCS_SDAPI BLE_temperature BLE_HeartRate writable_gatt ... more

Files at this revision

API Documentation at this revision

Comitter:
Rohit Grover
Date:
Tue Sep 02 16:42:56 2014 +0100
Parent:
58:de6b64cd7f21
Child:
60:e861f2041469
Commit message:
Release 0.1.1
=============

Minor bugfix release.

Bugfixes
~~~~~~~~

- drop duplicate app_timer.cpp; it's already present in the mbed SDK.
- add missing code for custom_add_in_descriptor() to custom_helper.cpp

Compatibility
~~~~~~~~~~~~~

Compatible with revision 0.1.0 of the BLE_API.

Changed in this revision

btle/custom/custom_helper.cpp Show annotated file Show diff for this revision Revisions of this file
nordic/app_common/app_timer.cpp Show diff for this revision Revisions of this file
--- a/btle/custom/custom_helper.cpp	Tue Sep 02 16:15:26 2014 +0100
+++ b/btle/custom/custom_helper.cpp	Tue Sep 02 16:42:56 2014 +0100
@@ -245,3 +245,53 @@
 
     return ERROR_NONE;
 }
+
+
+
+/**************************************************************************/
+/*!
+    @brief      Adds a new descriptor to the custom service, assigning
+                value, a UUID add-on value, etc.
+
+    @param[in]  char_handle
+    @param[in]  p_uuid            The 16-bit value to add to the base UUID
+                                  for this descriptor (normally >1
+                                  since 1 is typically used by the primary
+                                  service).
+    @param[in]  max_length        The maximum length of this descriptor
+
+    @returns
+    @retval     ERROR_NONE        Everything executed normally
+*/
+/**************************************************************************/
+error_t custom_add_in_descriptor(uint16_t    char_handle,
+                                             ble_uuid_t *p_uuid,
+                                             uint8_t    *p_data,
+                                             uint16_t    min_length,
+                                             uint16_t    max_length,
+                                             uint16_t   *p_desc_handle)
+{
+    /* Descriptor metadata */
+    ble_gatts_attr_md_t   desc_md = {0};
+
+    desc_md.vloc = BLE_GATTS_VLOC_STACK;
+    desc_md.vlen = (min_length == max_length) ? 0 : 1;
+
+    /* Make it readable and writable */
+    BLE_GAP_CONN_SEC_MODE_SET_OPEN(&desc_md.read_perm);
+    BLE_GAP_CONN_SEC_MODE_SET_OPEN(&desc_md.write_perm);
+
+    ble_gatts_attr_t attr_desc = {0};
+
+    attr_desc.p_uuid    = p_uuid;
+    attr_desc.p_attr_md = &desc_md;
+    attr_desc.init_len  = min_length;
+    attr_desc.max_len   = max_length;
+    attr_desc.p_value   = p_data;
+
+    ASSERT_STATUS ( sd_ble_gatts_descriptor_add(char_handle,
+                                                &attr_desc,
+                                                p_desc_handle));
+
+    return ERROR_NONE;
+}
--- a/nordic/app_common/app_timer.cpp	Tue Sep 02 16:15:26 2014 +0100
+++ /dev/null	Thu Jan 01 00:00:00 1970 +0000
@@ -1,1151 +0,0 @@
-/* Copyright (c) 2012 Nordic Semiconductor. All Rights Reserved.
- *
- * The information contained herein is property of Nordic Semiconductor ASA.
- * Terms and conditions of usage are described in detail in NORDIC
- * SEMICONDUCTOR STANDARD SOFTWARE LICENSE AGREEMENT.
- *
- * Licensees are granted free, non-transferable use of the information. NO
- * WARRANTY of ANY KIND is provided. This heading must NOT be removed from
- * the file.
- *
- */
-
-#include "app_timer.h"
-#include <stdlib.h>
-#include "nrf51.h"
-#include "nrf51_bitfields.h"
-#include "nrf_soc.h"
-#include "app_error.h"
-#include "nrf_delay.h"
-#include "app_util.h"
-#include "app_util_platform.h"
-
-
-#define RTC1_IRQ_PRI            APP_IRQ_PRIORITY_LOW                        /**< Priority of the RTC1 interrupt (used for checking for timeouts and executing timeout handlers). */
-#define SWI0_IRQ_PRI            APP_IRQ_PRIORITY_LOW                        /**< Priority of the SWI0 interrupt (used for updating the timer list). */
-
-// The current design assumes that both interrupt handlers run at the same interrupt level.
-// If this is to be changed, protection must be added to prevent them from interrupting each other
-// (e.g. by using guard/trigger flags).
-STATIC_ASSERT(RTC1_IRQ_PRI == SWI0_IRQ_PRI);
-
-#define APP_HIGH_USER_ID        0                                           /**< User Id for the Application High "user". */
-#define APP_LOW_USER_ID         1                                           /**< User Id for the Application Low "user". */
-#define THREAD_MODE_USER_ID     2                                           /**< User Id for the Thread Mode "user". */
-
-#define RTC_COMPARE_OFFSET_MIN  3                                           /**< Minimum offset between the current RTC counter value and the Capture Compare register. Although the nRF51 Series User Specification recommends this value to be 2, we use 3 to be safer.*/
-
-#define MAX_RTC_TASKS_DELAY     47                                          /**< Maximum delay until an RTC task is executed. */
-
-/**@brief Timer allocation state type. */
-typedef enum
-{
-    STATE_FREE,                                                             /**< The timer node is available. */
-    STATE_ALLOCATED                                                         /**< The timer node has been allocated. */
-} timer_alloc_state_t;
-
-/**@brief Timer node type. The nodes will be used form a linked list of running timers. */
-typedef struct
-{
-    timer_alloc_state_t         state;                                      /**< Timer allocation state. */
-    app_timer_mode_t            mode;                                       /**< Timer mode. */
-    uint32_t                    ticks_to_expire;                            /**< Number of ticks from previous timer interrupt to timer expiry. */
-    uint32_t                    ticks_at_start;                             /**< Current RTC counter value when the timer was started. */
-    uint32_t                    ticks_first_interval;                       /**< Number of ticks in the first timer interval. */
-    uint32_t                    ticks_periodic_interval;                    /**< Timer period (for repeating timers). */
-    bool                        is_running;                                 /**< True if timer is running, False otherwise. */
-    app_timer_timeout_handler_t p_timeout_handler;                          /**< Pointer to function to be executed when the timer expires. */
-    void *                      p_context;                                  /**< General purpose pointer. Will be passed to the timeout handler when the timer expires. */
-    app_timer_id_t              next;                                       /**< Id of next timer in list of running timers. */
-} timer_node_t;
-
-STATIC_ASSERT(sizeof(timer_node_t) <= APP_TIMER_NODE_SIZE);
-STATIC_ASSERT(sizeof(timer_node_t) % 4 == 0);
-
-/**@brief Set of available timer operation types. */
-typedef enum
-{
-    TIMER_USER_OP_TYPE_NONE,                                                /**< Invalid timer operation type. */
-    TIMER_USER_OP_TYPE_START,                                               /**< Timer operation type Start. */
-    TIMER_USER_OP_TYPE_STOP,                                                /**< Timer operation type Stop. */
-    TIMER_USER_OP_TYPE_STOP_ALL                                             /**< Timer operation type Stop All. */
-} timer_user_op_type_t;
-
-/**@brief Structure describing a timer start operation. */
-typedef struct
-{
-    uint32_t ticks_at_start;                                                /**< Current RTC counter value when the timer was started. */
-    uint32_t ticks_first_interval;                                          /**< Number of ticks in the first timer interval. */
-    uint32_t ticks_periodic_interval;                                       /**< Timer period (for repeating timers). */
-    void *   p_context;                                                     /**< General purpose pointer. Will be passed to the timeout handler when the timer expires. */
-} timer_user_op_start_t;
-
-/**@brief Structure describing a timer operation. */
-typedef struct
-{
-    timer_user_op_type_t op_type;                                           /**< Timer operation type. */
-    app_timer_id_t       timer_id;                                          /**< Id of timer on which the operation is to be performed. */
-    union
-    {
-        timer_user_op_start_t start;                                        /**< Structure describing a timer start operation. */
-    } params;
-} timer_user_op_t;
-
-STATIC_ASSERT(sizeof(timer_user_op_t) <= APP_TIMER_USER_OP_SIZE);
-STATIC_ASSERT(sizeof(timer_user_op_t) % 4 == 0);
-
-/**@brief Structure describing a timer user.
- *
- * @details For each user of the timer module, there will be a timer operations queue. This queue
- *          will hold timer operations issued by this user until the timer interrupt handler
- *          processes these operations. For the current implementation, there will be one user for
- *          each interrupt level available to the application (APP_HIGH, APP_LOW and THREAD_MODE),
- *          but the module can easily be modified to e.g. have one queue per process when using an
- *          RTOS. The purpose of the queues is to be able to have a completely lockless timer
- *          implementation.
- */
-typedef struct
-{
-    uint8_t           first;                                                    /**< Index of first entry to have been inserted in the queue (i.e. the next entry to be executed). */
-    uint8_t           last;                                                     /**< Index of last entry to have been inserted in the queue. */
-    uint8_t           user_op_queue_size;                                       /**< Queue size. */
-    timer_user_op_t * p_user_op_queue;                                          /**< Queue buffer. */
-} timer_user_t;
-
-STATIC_ASSERT(sizeof(timer_user_t) == APP_TIMER_USER_SIZE);
-STATIC_ASSERT(sizeof(timer_user_t) % 4 == 0);
-
-/**@brief User id type.
- *
- * @details In the current implementation, this will automatically be generated from the current
- *          interrupt level.
- */
-typedef uint32_t timer_user_id_t;
-
-#define CONTEXT_QUEUE_SIZE_MAX      (2)                                         /**< Timer internal elapsed ticks queue size. */
-
-static uint8_t                       m_node_array_size;                         /**< Size of timer node array. */
-static timer_node_t *                mp_nodes = NULL;                           /**< Array of timer nodes. */
-static uint8_t                       m_user_array_size;                         /**< Size of timer user array. */
-static timer_user_t *                mp_users;                                  /**< Array of timer users. */
-static app_timer_id_t                m_timer_id_head;                           /**< First timer in list of running timers. */
-static uint32_t                      m_ticks_latest;                            /**< Last known RTC counter value. */
-static uint32_t                      m_ticks_elapsed[CONTEXT_QUEUE_SIZE_MAX];   /**< Timer internal elapsed ticks queue. */
-static uint8_t                       m_ticks_elapsed_q_read_ind;                /**< Timer internal elapsed ticks queue read index. */
-static uint8_t                       m_ticks_elapsed_q_write_ind;               /**< Timer internal elapsed ticks queue write index. */
-static app_timer_evt_schedule_func_t m_evt_schedule_func;                       /**< Pointer to function for propagating timeout events to the scheduler. */
-static bool                          m_rtc1_running;                            /**< Boolean indicating if RTC1 is running. */
-static volatile uint64_t             overflowBits;                              /**< The upper 40 bits of the 64-bit value returned by cnt_get() */
-
-
-/**@brief Function for initializing the RTC1 counter.
- *
- * @param[in] prescaler   Value of the RTC1 PRESCALER register. Set to 0 for no prescaling.
- */
-static void rtc1_init(uint32_t prescaler)
-{
-    NRF_RTC1->PRESCALER = prescaler;
-    NVIC_SetPriority(RTC1_IRQn, RTC1_IRQ_PRI);
-}
-
-
-/**@brief Function for starting the RTC1 timer.
- */
-static void rtc1_start(void)
-{
-    if (m_rtc1_running) {
-        return;
-    }
-
-    NRF_RTC1->EVTENSET = RTC_EVTEN_COMPARE0_Msk;
-    NRF_RTC1->INTENSET = RTC_INTENSET_COMPARE0_Msk | RTC_INTENSET_OVRFLW_Msk;
-
-    NVIC_ClearPendingIRQ(RTC1_IRQn);
-    NVIC_EnableIRQ(RTC1_IRQn);
-
-    NRF_RTC1->TASKS_START = 1;
-    nrf_delay_us(MAX_RTC_TASKS_DELAY);
-
-    m_rtc1_running = true;
-}
-
-
-/**@brief Function for stopping the RTC1 timer.
- */
-static void rtc1_stop(void)
-{
-    if (!m_rtc1_running) {
-        return;
-    }
-
-    NVIC_DisableIRQ(RTC1_IRQn);
-
-    NRF_RTC1->EVTENCLR = RTC_EVTEN_COMPARE0_Msk;
-    NRF_RTC1->INTENCLR = RTC_INTENSET_COMPARE0_Msk | RTC_INTENSET_OVRFLW_Msk;
-
-    NRF_RTC1->TASKS_STOP = 1;
-    nrf_delay_us(MAX_RTC_TASKS_DELAY);
-
-    NRF_RTC1->TASKS_CLEAR = 1;
-    m_ticks_latest        = 0;
-    nrf_delay_us(MAX_RTC_TASKS_DELAY);
-
-    m_rtc1_running = false;
-}
-
-
-/**@brief Function for returning the current value of the RTC1 counter.
- *
- * @return     Current value of the RTC1 counter.
- */
-static __INLINE uint32_t rtc1_counter_get(void)
-{
-    return NRF_RTC1->COUNTER;
-}
-
-
-/**@brief Function for computing the difference between two RTC1 counter values.
- *
- * @return     Number of ticks elapsed from ticks_old to ticks_now.
- */
-static __INLINE uint32_t ticks_diff_get(uint32_t ticks_now, uint32_t ticks_old)
-{
-    return ((ticks_now - ticks_old) & MAX_RTC_COUNTER_VAL);
-}
-
-
-/**@brief Function for setting the RTC1 Capture Compare register 0, and enabling the corresponding
- *        event.
- *
- * @param[in] value   New value of Capture Compare register 0.
- */
-static __INLINE void rtc1_compare0_set(uint32_t value)
-{
-    NRF_RTC1->CC[0] = value;
-}
-
-
-/**@brief Function for inserting a timer in the timer list.
- *
- * @param[in]  timer_id   Id of timer to insert.
- */
-static void timer_list_insert(app_timer_id_t timer_id)
-{
-    timer_node_t * p_timer = &mp_nodes[timer_id];
-
-    if (m_timer_id_head == TIMER_NULL)
-    {
-        m_timer_id_head = timer_id;
-    }
-    else
-    {
-        if (p_timer->ticks_to_expire <= mp_nodes[m_timer_id_head].ticks_to_expire)
-        {
-            mp_nodes[m_timer_id_head].ticks_to_expire -= p_timer->ticks_to_expire;
-
-            p_timer->next   = m_timer_id_head;
-            m_timer_id_head = timer_id;
-        }
-        else
-        {
-            app_timer_id_t previous;
-            app_timer_id_t current;
-            uint32_t       ticks_to_expire;
-
-            ticks_to_expire = p_timer->ticks_to_expire;
-            previous        = m_timer_id_head;
-            current         = m_timer_id_head;
-
-            while ((current != TIMER_NULL) && (ticks_to_expire > mp_nodes[current].ticks_to_expire))
-            {
-                ticks_to_expire -= mp_nodes[current].ticks_to_expire;
-                previous         = current;
-                current          = mp_nodes[current].next;
-            }
-
-            if (current != TIMER_NULL)
-            {
-                mp_nodes[current].ticks_to_expire -= ticks_to_expire;
-            }
-
-            p_timer->ticks_to_expire = ticks_to_expire;
-            p_timer->next            = current;
-            mp_nodes[previous].next  = timer_id;
-        }
-    }
-}
-
-
-/**@brief Function for removing a timer from the timer queue.
- *
- * @param[in]  timer_id   Id of timer to remove.
- */
-static void timer_list_remove(app_timer_id_t timer_id)
-{
-    app_timer_id_t previous;
-    app_timer_id_t current;
-    uint32_t       timeout;
-
-    // Find the timer's position in timer list
-    previous = m_timer_id_head;
-    current  = previous;
-
-    while (current != TIMER_NULL)
-    {
-        if (current == timer_id)
-        {
-            break;
-        }
-        previous = current;
-        current  = mp_nodes[current].next;
-    }
-
-    // Timer not in active list
-    if (current == TIMER_NULL)
-    {
-        return;
-    }
-
-    // Timer is the first in the list
-    if (previous == current)
-    {
-        m_timer_id_head = mp_nodes[m_timer_id_head].next;
-
-        // No more timers in the list. Disable RTC1.
-        if (m_timer_id_head == TIMER_NULL)
-        {
-            rtc1_stop();
-        }
-    }
-
-    // Remaining timeout between next timeout
-    timeout = mp_nodes[current].ticks_to_expire;
-
-    // Link previous timer with next of this timer, i.e. removing the timer from list
-    mp_nodes[previous].next = mp_nodes[current].next;
-
-    // If this is not the last timer, increment the next timer by this timer timeout
-    current = mp_nodes[previous].next;
-    if (current != TIMER_NULL)
-    {
-        mp_nodes[current].ticks_to_expire += timeout;
-    }
-}
-
-
-/**@brief Function for scheduling a check for timeouts by generating a RTC1 interrupt.
- */
-static void timer_timeouts_check_sched(void)
-{
-    NVIC_SetPendingIRQ(RTC1_IRQn);
-}
-
-
-/**@brief Function for scheduling a timer list update by generating a SWI0 interrupt.
- */
-static void timer_list_handler_sched(void)
-{
-    NVIC_SetPendingIRQ(SWI0_IRQn);
-}
-
-
-/**@brief Function for executing an application timeout handler, either by calling it directly, or
- *        by passing an event to the @ref app_scheduler.
- *
- * @param[in]  p_timer   Pointer to expired timer.
- */
-static void timeout_handler_exec(timer_node_t * p_timer)
-{
-    if (m_evt_schedule_func != NULL)
-    {
-        uint32_t err_code = m_evt_schedule_func(p_timer->p_timeout_handler, p_timer->p_context);
-        APP_ERROR_CHECK(err_code);
-    }
-    else
-    {
-        p_timer->p_timeout_handler(p_timer->p_context);
-    }
-}
-
-
-/**@brief Function for checking for expired timers.
- */
-static void timer_timeouts_check(void)
-{
-    // Handle expired of timer
-    if (m_timer_id_head != TIMER_NULL)
-    {
-        app_timer_id_t  timer_id;
-        uint32_t        ticks_elapsed;
-        uint32_t        ticks_expired;
-
-        // Initialize actual elapsed ticks being consumed to 0
-        ticks_expired = 0;
-
-        // ticks_elapsed is collected here, job will use it
-        ticks_elapsed = ticks_diff_get(rtc1_counter_get(), m_ticks_latest);
-
-        // Auto variable containing the head of timers expiring
-        timer_id = m_timer_id_head;
-
-        // Expire all timers within ticks_elapsed and collect ticks_expired
-        while (timer_id != TIMER_NULL)
-        {
-            timer_node_t * p_timer;
-
-            // Auto variable for current timer node
-            p_timer = &mp_nodes[timer_id];
-
-            // Do nothing if timer did not expire
-            if (ticks_elapsed < p_timer->ticks_to_expire)
-            {
-                break;
-            }
-
-            // Decrement ticks_elapsed and collect expired ticks
-            ticks_elapsed -= p_timer->ticks_to_expire;
-            ticks_expired += p_timer->ticks_to_expire;
-
-            // Move to next timer
-            timer_id = p_timer->next;
-
-            // Execute Task
-            timeout_handler_exec(p_timer);
-        }
-
-        // Prepare to queue the ticks expired in the m_ticks_elapsed queue.
-        if (m_ticks_elapsed_q_read_ind == m_ticks_elapsed_q_write_ind)
-        {
-            // The read index of the queue is equal to the write index. This means the new
-            // value of ticks_expired should be stored at a new location in the m_ticks_elapsed
-            // queue (which is implemented as a double buffer).
-
-            // Check if there will be a queue overflow.
-            if (++m_ticks_elapsed_q_write_ind == CONTEXT_QUEUE_SIZE_MAX)
-            {
-                // There will be a queue overflow. Hence the write index should point to the start
-                // of the queue.
-                m_ticks_elapsed_q_write_ind = 0;
-            }
-        }
-
-        // Queue the ticks expired.
-        m_ticks_elapsed[m_ticks_elapsed_q_write_ind] = ticks_expired;
-
-        timer_list_handler_sched();
-    }
-}
-
-
-/**@brief Function for acquiring the number of ticks elapsed.
- *
- * @param[out] p_ticks_elapsed   Number of ticks elapsed.
- *
- * @return     TRUE if elapsed ticks was read from queue, FALSE otherwise.
- */
-static bool elapsed_ticks_acquire(uint32_t * p_ticks_elapsed)
-{
-    // Pick the elapsed value from queue
-    if (m_ticks_elapsed_q_read_ind != m_ticks_elapsed_q_write_ind)
-    {
-        // Dequeue elapsed value
-        m_ticks_elapsed_q_read_ind++;
-        if (m_ticks_elapsed_q_read_ind == CONTEXT_QUEUE_SIZE_MAX)
-        {
-            m_ticks_elapsed_q_read_ind = 0;
-        }
-
-        *p_ticks_elapsed = m_ticks_elapsed[m_ticks_elapsed_q_read_ind];
-
-        m_ticks_latest += *p_ticks_elapsed;
-        m_ticks_latest &= MAX_RTC_COUNTER_VAL;
-
-        return true;
-    }
-    else
-    {
-        // No elapsed value in queue
-        *p_ticks_elapsed = 0;
-        return false;
-    }
-}
-
-
-/**@brief Function for handling the timer list deletions.
- *
- * @return     TRUE if Capture Compare register must be updated, FALSE otherwise.
- */
-static bool list_deletions_handler(void)
-{
-    app_timer_id_t timer_id_old_head;
-    uint8_t        user_id;
-
-    // Remember the old head, so as to decide if new compare needs to be set
-    timer_id_old_head = m_timer_id_head;
-
-    user_id = m_user_array_size;
-    while (user_id--)
-    {
-        timer_user_t * p_user         = &mp_users[user_id];
-        uint8_t        user_ops_first = p_user->first;
-
-        while (user_ops_first != p_user->last)
-        {
-            timer_node_t *    p_timer;
-            timer_user_op_t * p_user_op = &p_user->p_user_op_queue[user_ops_first];
-
-            // Traverse to next operation in queue
-            user_ops_first++;
-            if (user_ops_first == p_user->user_op_queue_size)
-            {
-                user_ops_first = 0;
-            }
-
-            switch (p_user_op->op_type)
-            {
-                case TIMER_USER_OP_TYPE_STOP:
-                    // Delete node if timer is running
-                    p_timer = &mp_nodes[p_user_op->timer_id];
-                    if (p_timer->is_running)
-                    {
-                        timer_list_remove(p_user_op->timer_id);
-                        p_timer->is_running = false;
-                    }
-                    break;
-
-                case TIMER_USER_OP_TYPE_STOP_ALL:
-                    // Delete list of running timers, and mark all timers as not running
-                    while (m_timer_id_head != TIMER_NULL)
-                    {
-                        timer_node_t * p_head = &mp_nodes[m_timer_id_head];
-
-                        p_head->is_running = false;
-                        m_timer_id_head    = p_head->next;
-                    }
-                    break;
-
-                default:
-                    // No implementation needed.
-                    break;
-            }
-        }
-    }
-
-    // Detect change in head of the list
-    return (m_timer_id_head != timer_id_old_head);
-}
-
-
-/**@brief Function for updating the timer list for expired timers.
- *
- * @param[in]  ticks_elapsed         Number of elapsed ticks.
- * @param[in]  ticks_previous        Previous known value of the RTC counter.
- * @param[out] p_restart_list_head   List of repeating timers to be restarted.
- */
-static void expired_timers_handler(uint32_t         ticks_elapsed,
-                                   uint32_t         ticks_previous,
-                                   app_timer_id_t * p_restart_list_head)
-{
-    uint32_t ticks_expired = 0;
-
-    while (m_timer_id_head != TIMER_NULL)
-    {
-        timer_node_t * p_timer;
-        app_timer_id_t id_expired;
-
-        // Auto variable for current timer node
-        p_timer = &mp_nodes[m_timer_id_head];
-
-        // Do nothing if timer did not expire
-        if (ticks_elapsed < p_timer->ticks_to_expire)
-        {
-            p_timer->ticks_to_expire -= ticks_elapsed;
-            break;
-        }
-
-        // Decrement ticks_elapsed and collect expired ticks
-        ticks_elapsed -= p_timer->ticks_to_expire;
-        ticks_expired += p_timer->ticks_to_expire;
-
-        // Timer expired, set ticks_to_expire zero
-        p_timer->ticks_to_expire = 0;
-        p_timer->is_running      = false;
-
-        // Remove the expired timer from head
-        id_expired      = m_timer_id_head;
-        m_timer_id_head = p_timer->next;
-
-        // Timer will be restarted if periodic
-        if (p_timer->ticks_periodic_interval != 0)
-        {
-            p_timer->ticks_at_start       = (ticks_previous + ticks_expired) & MAX_RTC_COUNTER_VAL;
-            p_timer->ticks_first_interval = p_timer->ticks_periodic_interval;
-            p_timer->next                 = *p_restart_list_head;
-            *p_restart_list_head          = id_expired;
-        }
-    }
-}
-
-
-/**@brief Function for handling timer list insertions.
- *
- * @param[in]  p_restart_list_head   List of repeating timers to be restarted.
- *
- * @return     TRUE if Capture Compare register must be updated, FALSE otherwise.
- */
-static bool list_insertions_handler(app_timer_id_t restart_list_head)
-{
-    app_timer_id_t timer_id_old_head;
-    uint8_t        user_id;
-
-    // Remember the old head, so as to decide if new compare needs to be set
-    timer_id_old_head = m_timer_id_head;
-
-    user_id = m_user_array_size;
-    while (user_id--)
-    {
-        timer_user_t * p_user = &mp_users[user_id];
-
-        // Handle insertions of timers
-        while ((restart_list_head != TIMER_NULL) || (p_user->first != p_user->last))
-        {
-            app_timer_id_t id_start;
-            timer_node_t * p_timer;
-
-            if (restart_list_head != TIMER_NULL)
-            {
-                id_start          = restart_list_head;
-                p_timer           = &mp_nodes[id_start];
-                restart_list_head = p_timer->next;
-            }
-            else
-            {
-                timer_user_op_t * p_user_op = &p_user->p_user_op_queue[p_user->first];
-
-                p_user->first++;
-                if (p_user->first == p_user->user_op_queue_size)
-                {
-                    p_user->first = 0;
-                }
-
-                id_start = p_user_op->timer_id;
-                p_timer  = &mp_nodes[id_start];
-
-                if ((p_user_op->op_type != TIMER_USER_OP_TYPE_START) || p_timer->is_running)
-                {
-                    continue;
-                }
-
-                p_timer->ticks_at_start          = p_user_op->params.start.ticks_at_start;
-                p_timer->ticks_first_interval    = p_user_op->params.start.ticks_first_interval;
-                p_timer->ticks_periodic_interval = p_user_op->params.start.ticks_periodic_interval;
-                p_timer->p_context               = p_user_op->params.start.p_context;
-            }
-
-            // Prepare the node to be inserted
-            if (
-                 ((p_timer->ticks_at_start - m_ticks_latest) & MAX_RTC_COUNTER_VAL)
-                 <
-                 (MAX_RTC_COUNTER_VAL / 2)
-                )
-            {
-                p_timer->ticks_to_expire = ticks_diff_get(p_timer->ticks_at_start, m_ticks_latest) +
-                                           p_timer->ticks_first_interval;
-            }
-            else
-            {
-                uint32_t delta_current_start;
-
-                delta_current_start = ticks_diff_get(m_ticks_latest, p_timer->ticks_at_start);
-                if (p_timer->ticks_first_interval > delta_current_start)
-                {
-                    p_timer->ticks_to_expire = p_timer->ticks_first_interval - delta_current_start;
-                }
-                else
-                {
-                    p_timer->ticks_to_expire = 0;
-                }
-            }
-
-            p_timer->ticks_at_start       = 0;
-            p_timer->ticks_first_interval = 0;
-            p_timer->is_running           = true;
-            p_timer->next                 = TIMER_NULL;
-
-            // Insert into list
-            timer_list_insert(id_start);
-        }
-    }
-
-    return (m_timer_id_head != timer_id_old_head);
-}
-
-
-/**@brief Function for updating the Capture Compare register.
- */
-static void compare_reg_update(app_timer_id_t timer_id_head_old)
-{
-    // Setup the timeout for timers on the head of the list
-    if (m_timer_id_head != TIMER_NULL)
-    {
-        uint32_t ticks_to_expire = mp_nodes[m_timer_id_head].ticks_to_expire;
-        uint32_t pre_counter_val = rtc1_counter_get();
-        uint32_t cc              = m_ticks_latest;
-        uint32_t ticks_elapsed   = ticks_diff_get(pre_counter_val, cc) + RTC_COMPARE_OFFSET_MIN;
-
-        if (!m_rtc1_running)
-        {
-            // No timers were already running, start RTC
-            rtc1_start();
-        }
-
-        cc += (ticks_elapsed < ticks_to_expire) ? ticks_to_expire : ticks_elapsed;
-        cc &= MAX_RTC_COUNTER_VAL;
-
-        rtc1_compare0_set(cc);
-
-        uint32_t post_counter_val = rtc1_counter_get();
-
-        if ((ticks_diff_get(post_counter_val, pre_counter_val) + RTC_COMPARE_OFFSET_MIN) > ticks_diff_get(cc, pre_counter_val))
-        {
-            // When this happens the COMPARE event may not be triggered by the RTC.
-            // The nRF51 Series User Specification states that if the COUNTER value is N
-            // (i.e post_counter_val = N), writing N or N+1 to a CC register may not trigger a
-            // COMPARE event. Hence the RTC interrupt is forcefully pended by calling the following
-            // function.
-            timer_timeouts_check_sched();
-        }
-    }
-    else
-    {
-        // No timers are running, stop RTC
-        rtc1_stop();
-    }
-}
-
-
-/**@brief Function for handling changes to the timer list.
- */
-static void timer_list_handler(void)
-{
-    app_timer_id_t restart_list_head = TIMER_NULL;
-    uint32_t       ticks_elapsed;
-    uint32_t       ticks_previous;
-    bool           ticks_have_elapsed;
-    bool           compare_update;
-    app_timer_id_t timer_id_head_old;
-
-    // Back up the previous known tick and previous list head
-    ticks_previous    = m_ticks_latest;
-    timer_id_head_old = m_timer_id_head;
-
-    // Get number of elapsed ticks
-    ticks_have_elapsed = elapsed_ticks_acquire(&ticks_elapsed);
-
-    // Handle list deletions
-    compare_update = list_deletions_handler();
-
-    // Handle expired timers
-    if (ticks_have_elapsed)
-    {
-        expired_timers_handler(ticks_elapsed, ticks_previous, &restart_list_head);
-        compare_update = true;
-    }
-
-    // Handle list insertions
-    if (list_insertions_handler(restart_list_head))
-    {
-        compare_update = true;
-    }
-
-    // Update compare register if necessary
-    if (compare_update)
-    {
-        compare_reg_update(timer_id_head_old);
-    }
-}
-
-
-/**@brief Function for enqueueing a new operations queue entry.
- *
- * @param[in]  p_user     User that the entry is to be enqueued for.
- * @param[in]  last_index Index of the next last index to be enqueued.
- */
-static void user_op_enque(timer_user_t * p_user, app_timer_id_t last_index)
-{
-    p_user->last = last_index;
-}
-
-
-/**@brief Function for allocating a new operations queue entry.
- *
- * @param[in]  p_user       User that the entry is to be allocated for.
- * @param[out] p_last_index Index of the next last index to be enqueued.
- *
- * @return     Pointer to allocated queue entry, or NULL if queue is full.
- */
-static timer_user_op_t * user_op_alloc(timer_user_t * p_user, app_timer_id_t * p_last_index)
-{
-    app_timer_id_t    last;
-    timer_user_op_t * p_user_op;
-
-    last = p_user->last + 1;
-    if (last == p_user->user_op_queue_size)
-    {
-        // Overflow case.
-        last = 0;
-    }
-    if (last == p_user->first)
-    {
-        // Queue is full.
-        return NULL;
-    }
-
-    *p_last_index = last;
-    p_user_op     = &p_user->p_user_op_queue[p_user->last];
-
-    return p_user_op;
-}
-
-
-/**@brief Function for scheduling a Timer Start operation.
- *
- * @param[in]  user_id           Id of user calling this function.
- * @param[in]  timer_id          Id of timer to start.
- * @param[in]  timeout_initial   Time (in ticks) to first timer expiry.
- * @param[in]  timeout_periodic  Time (in ticks) between periodic expiries.
- * @param[in]  p_context         General purpose pointer. Will be passed to the timeout handler when
- *                               the timer expires.
- * @return     NRF_SUCCESS on success, otherwise an error code.
- */
-static uint32_t timer_start_op_schedule(timer_user_id_t user_id,
-                                        app_timer_id_t  timer_id,
-                                        uint32_t        timeout_initial,
-                                        uint32_t        timeout_periodic,
-                                        void *          p_context)
-{
-    app_timer_id_t last_index;
-
-    timer_user_op_t * p_user_op = user_op_alloc(&mp_users[user_id], &last_index);
-    if (p_user_op == NULL)
-    {
-        return NRF_ERROR_NO_MEM;
-    }
-
-    p_user_op->op_type                              = TIMER_USER_OP_TYPE_START;
-    p_user_op->timer_id                             = timer_id;
-    p_user_op->params.start.ticks_at_start          = rtc1_counter_get();
-    p_user_op->params.start.ticks_first_interval    = timeout_initial;
-    p_user_op->params.start.ticks_periodic_interval = timeout_periodic;
-    p_user_op->params.start.p_context               = p_context;
-
-    user_op_enque(&mp_users[user_id], last_index);
-
-    timer_list_handler_sched();
-
-    return NRF_SUCCESS;
-}
-
-
-/**@brief Function for scheduling a Timer Stop operation.
- *
- * @param[in]  user_id    Id of user calling this function.
- * @param[in]  timer_id   Id of timer to stop.
- *
- * @return NRF_SUCCESS on successful scheduling a timer stop operation. NRF_ERROR_NO_MEM when there
- *         is no memory left to schedule the timer stop operation.
- */
-static uint32_t timer_stop_op_schedule(timer_user_id_t user_id, app_timer_id_t timer_id)
-{
-    app_timer_id_t last_index;
-
-    timer_user_op_t * p_user_op = user_op_alloc(&mp_users[user_id], &last_index);
-    if (p_user_op == NULL)
-    {
-        return NRF_ERROR_NO_MEM;
-    }
-
-    p_user_op->op_type  = TIMER_USER_OP_TYPE_STOP;
-    p_user_op->timer_id = timer_id;
-
-    user_op_enque(&mp_users[user_id], last_index);
-
-    timer_list_handler_sched();
-
-    return NRF_SUCCESS;
-}
-
-
-/**@brief Function for scheduling a Timer Stop All operation.
- *
- * @param[in]  user_id    Id of user calling this function.
- */
-static uint32_t timer_stop_all_op_schedule(timer_user_id_t user_id)
-{
-    app_timer_id_t last_index;
-
-    timer_user_op_t * p_user_op = user_op_alloc(&mp_users[user_id], &last_index);
-    if (p_user_op == NULL)
-    {
-        return NRF_ERROR_NO_MEM;
-    }
-
-    p_user_op->op_type  = TIMER_USER_OP_TYPE_STOP_ALL;
-    p_user_op->timer_id = TIMER_NULL;
-
-    user_op_enque(&mp_users[user_id], last_index);
-
-    timer_list_handler_sched();
-
-    return NRF_SUCCESS;
-}
-
-
-/**@brief Function for handling the RTC1 interrupt.
- *
- * @details Checks for timeouts, and executes timeout handlers for expired timers.
- */
-extern "C" void RTC1_IRQHandler(void)
-{
-    // Clear all events (also unexpected ones)
-    NRF_RTC1->EVENTS_COMPARE[0] = 0;
-    NRF_RTC1->EVENTS_COMPARE[1] = 0;
-    NRF_RTC1->EVENTS_COMPARE[2] = 0;
-    NRF_RTC1->EVENTS_COMPARE[3] = 0;
-    NRF_RTC1->EVENTS_TICK       = 0;
-    if (NRF_RTC1->EVENTS_OVRFLW) {
-        overflowBits += (1 << 24);
-    }
-    NRF_RTC1->EVENTS_OVRFLW     = 0;
-
-    // Check for expired timers
-    timer_timeouts_check();
-}
-
-/**@brief Function for handling the SWI0 interrupt.
- *
- * @details Performs all updates to the timer list.
- */
-extern "C" void SWI0_IRQHandler(void)
-{
-    timer_list_handler();
-}
-
-uint32_t app_timer_init(uint32_t                      prescaler,
-                        uint8_t                       max_timers,
-                        uint8_t                       op_queues_size,
-                        void *                        p_buffer,
-                        app_timer_evt_schedule_func_t evt_schedule_func)
-{
-    int i;
-
-    // Check that buffer is correctly aligned
-    if (!is_word_aligned(p_buffer))
-    {
-        return NRF_ERROR_INVALID_PARAM;
-    }
-    // Check for NULL buffer
-    if (p_buffer == NULL)
-    {
-        return NRF_ERROR_INVALID_PARAM;
-    }
-
-    // Stop RTC to prevent any running timers from expiring (in case of reinitialization)
-    rtc1_stop();
-
-    m_evt_schedule_func = evt_schedule_func;
-
-    // Initialize timer node array
-    m_node_array_size = max_timers;
-    mp_nodes          = (timer_node_t *) p_buffer;
-
-    for (i = 0; i < max_timers; i++)
-    {
-        mp_nodes[i].state      = STATE_FREE;
-        mp_nodes[i].is_running = false;
-    }
-
-    // Skip timer node array
-    p_buffer = &((uint8_t *)p_buffer)[max_timers * sizeof(timer_node_t)];
-
-    // Initialize users array
-    m_user_array_size = APP_TIMER_INT_LEVELS;
-    mp_users          = (timer_user_t *) p_buffer;
-
-    // Skip user array
-    p_buffer = &((uint8_t *)p_buffer)[APP_TIMER_INT_LEVELS * sizeof(timer_user_t)];
-
-    // Initialize operation queues
-    for (i = 0; i < APP_TIMER_INT_LEVELS; i++)
-    {
-        timer_user_t * p_user = &mp_users[i];
-
-        p_user->first              = 0;
-        p_user->last               = 0;
-        p_user->user_op_queue_size = op_queues_size;
-        p_user->p_user_op_queue    = (timer_user_op_t *) p_buffer;
-
-        // Skip operation queue
-        p_buffer = &((uint8_t *)p_buffer)[op_queues_size * sizeof(timer_user_op_t)];
-    }
-
-    m_timer_id_head             = TIMER_NULL;
-    m_ticks_elapsed_q_read_ind  = 0;
-    m_ticks_elapsed_q_write_ind = 0;
-
-    NVIC_ClearPendingIRQ(SWI0_IRQn);
-    NVIC_SetPriority(SWI0_IRQn, SWI0_IRQ_PRI);
-    NVIC_EnableIRQ(SWI0_IRQn);
-
-    rtc1_init(prescaler);
-    rtc1_start();
-
-    m_ticks_latest = rtc1_counter_get();
-
-    return NRF_SUCCESS;
-}
-
-
-uint32_t app_timer_create(app_timer_id_t *            p_timer_id,
-                          app_timer_mode_t            mode,
-                          app_timer_timeout_handler_t timeout_handler)
-{
-    int i;
-
-    // Check state and parameters
-    if (mp_nodes == NULL)
-    {
-        return NRF_ERROR_INVALID_STATE;
-    }
-    if (timeout_handler == NULL)
-    {
-        return NRF_ERROR_INVALID_PARAM;
-    }
-    if (p_timer_id == NULL)
-    {
-        return NRF_ERROR_INVALID_PARAM;
-    }
-
-    // Find free timer
-    for (i = 0; i < m_node_array_size; i++)
-    {
-        if (mp_nodes[i].state == STATE_FREE)
-        {
-            mp_nodes[i].state             = STATE_ALLOCATED;
-            mp_nodes[i].mode              = mode;
-            mp_nodes[i].p_timeout_handler = timeout_handler;
-
-            *p_timer_id = i;
-            return NRF_SUCCESS;
-        }
-    }
-
-    return NRF_ERROR_NO_MEM;
-}
-
-
-/**@brief Function for creating a timer user id from the current interrupt level.
- *
- * @return     Timer user id.
-*/
-static timer_user_id_t user_id_get(void)
-{
-    timer_user_id_t ret;
-
-    STATIC_ASSERT(APP_TIMER_INT_LEVELS == 3);
-
-    switch (current_int_priority_get())
-    {
-        case APP_IRQ_PRIORITY_HIGH:
-            ret = APP_HIGH_USER_ID;
-            break;
-
-        case APP_IRQ_PRIORITY_LOW:
-            ret = APP_LOW_USER_ID;
-            break;
-
-        default:
-            ret = THREAD_MODE_USER_ID;
-            break;
-    }
-
-    return ret;
-}
-
-
-uint32_t app_timer_start(app_timer_id_t timer_id, uint32_t timeout_ticks, void * p_context)
-{
-    uint32_t timeout_periodic;
-
-    // Check state and parameters
-    if (mp_nodes == NULL)
-    {
-        return NRF_ERROR_INVALID_STATE;
-    }
-    if ((timer_id >= m_node_array_size) || (timeout_ticks < APP_TIMER_MIN_TIMEOUT_TICKS))
-    {
-        return NRF_ERROR_INVALID_PARAM;
-    }
-    if (mp_nodes[timer_id].state != STATE_ALLOCATED)
-    {
-        return NRF_ERROR_INVALID_STATE;
-    }
-
-    // Schedule timer start operation
-    timeout_periodic = (mp_nodes[timer_id].mode == APP_TIMER_MODE_REPEATED) ? timeout_ticks : 0;
-
-    return timer_start_op_schedule(user_id_get(),
-                                   timer_id,
-                                   timeout_ticks,
-                                   timeout_periodic,
-                                   p_context);
-}
-
-
-uint32_t app_timer_stop(app_timer_id_t timer_id)
-{
-    // Check state and parameters
-    if (mp_nodes == NULL)
-    {
-        return NRF_ERROR_INVALID_STATE;
-    }
-    if (timer_id >= m_node_array_size)
-    {
-        return NRF_ERROR_INVALID_PARAM;
-    }
-    if (mp_nodes[timer_id].state != STATE_ALLOCATED)
-    {
-        return NRF_ERROR_INVALID_STATE;
-    }
-
-    // Schedule timer stop operation
-    return timer_stop_op_schedule(user_id_get(), timer_id);
-}
-
-
-uint32_t app_timer_stop_all(void)
-{
-    // Check state
-    if (mp_nodes == NULL)
-    {
-        return NRF_ERROR_INVALID_STATE;
-    }
-
-    return timer_stop_all_op_schedule(user_id_get());
-}
-
-
-uint32_t app_timer_cnt_get(uint64_t * p_ticks)
-{
-    *p_ticks = overflowBits | rtc1_counter_get();
-    return NRF_SUCCESS;
-}
-
-
-uint32_t app_timer_cnt_diff_compute(uint32_t   ticks_to,
-                                    uint32_t   ticks_from,
-                                    uint32_t * p_ticks_diff)
-{
-    *p_ticks_diff = ticks_diff_get(ticks_to, ticks_from);
-    return NRF_SUCCESS;
-}