ble_conn_params.c

/**
 * Copyright (c) 2012 - 2017, Nordic Semiconductor ASA
 * 
 * All rights reserved.
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#include "ble_conn_params.h"
#include <stdlib.h>
#include "nordic_common.h"
#include "ble_hci.h"
#include "app_timer.h"
#include "ble_srv_common.h"
#include "app_util.h"


static ble_conn_params_init_t m_conn_params_config;     /**< Configuration as specified by the application. */
static ble_gap_conn_params_t  m_preferred_conn_params;  /**< Connection parameters preferred by the application. */
static uint8_t                m_update_count;           /**< Number of Connection Parameter Update messages that has currently been sent. */
static uint16_t               m_conn_handle;            /**< Current connection handle. */
static ble_gap_conn_params_t  m_current_conn_params;    /**< Connection parameters received in the most recent Connect event. */
APP_TIMER_DEF(m_conn_params_timer_id);                  /**< Connection parameters timer. */

static bool m_change_param = false;

static bool is_conn_params_ok(ble_gap_conn_params_t * p_conn_params)
{
    // Check if interval is within the acceptable range.
    // NOTE: Using max_conn_interval in the received event data because this contains
    //       the client's connection interval.
    if (
        (p_conn_params->max_conn_interval >= m_preferred_conn_params.min_conn_interval)
        &&
        (p_conn_params->max_conn_interval <= m_preferred_conn_params.max_conn_interval)
       )
    {
        return true;
    }
    else
    {
        return false;
    }
}


static void update_timeout_handler(void * p_context)
{
    UNUSED_PARAMETER(p_context);

    if (m_conn_handle != BLE_CONN_HANDLE_INVALID)
    {
        // Check if we have reached the maximum number of attempts
        m_update_count++;
        if (m_update_count <= m_conn_params_config.max_conn_params_update_count)
        {
            uint32_t err_code;

            // Parameters are not ok, send connection parameters update request.
            err_code = sd_ble_gap_conn_param_update(m_conn_handle, &m_preferred_conn_params);
            if ((err_code != NRF_SUCCESS) && (m_conn_params_config.error_handler != NULL))
            {
                m_conn_params_config.error_handler(err_code);
            }
        }
        else
        {
            m_update_count = 0;

            // Negotiation failed, disconnect automatically if this has been configured
            if (m_conn_params_config.disconnect_on_fail)
            {
                uint32_t err_code;

                err_code = sd_ble_gap_disconnect(m_conn_handle, BLE_HCI_CONN_INTERVAL_UNACCEPTABLE);
                if ((err_code != NRF_SUCCESS) && (m_conn_params_config.error_handler != NULL))
                {
                    m_conn_params_config.error_handler(err_code);
                }
            }

            // Notify the application that the procedure has failed
            if (m_conn_params_config.evt_handler != NULL)
            {
                ble_conn_params_evt_t evt;

                evt.evt_type = BLE_CONN_PARAMS_EVT_FAILED;
                m_conn_params_config.evt_handler(&evt);
            }
        }
    }
}


uint32_t ble_conn_params_init(const ble_conn_params_init_t * p_init)
{
    uint32_t err_code;

    m_conn_params_config = *p_init;
    m_change_param = false;
    if (p_init->p_conn_params != NULL)
    {
        m_preferred_conn_params = *p_init->p_conn_params;

        // Set the connection params in stack
        err_code = sd_ble_gap_ppcp_set(&m_preferred_conn_params);
        if (err_code != NRF_SUCCESS)
        {
            return err_code;
        }
    }
    else
    {
        // Fetch the connection params from stack
        err_code = sd_ble_gap_ppcp_get(&m_preferred_conn_params);
        if (err_code != NRF_SUCCESS)
        {
            return err_code;
        }
    }

    m_conn_handle  = BLE_CONN_HANDLE_INVALID;
    m_update_count = 0;

    return app_timer_create(&m_conn_params_timer_id,
                            APP_TIMER_MODE_SINGLE_SHOT,
                            update_timeout_handler);
}


uint32_t ble_conn_params_stop(void)
{
    return app_timer_stop(m_conn_params_timer_id);
}


static void conn_params_negotiation(void)
{
    // Start negotiation if the received connection parameters are not acceptable
    if (!is_conn_params_ok(&m_current_conn_params))
    {
        uint32_t err_code;
        uint32_t timeout_ticks;

        if (m_change_param)
        {
            // Notify the application that the procedure has failed
            if (m_conn_params_config.evt_handler != NULL)
            {
                ble_conn_params_evt_t evt;

                evt.evt_type = BLE_CONN_PARAMS_EVT_FAILED;
                m_conn_params_config.evt_handler(&evt);
            }
        }
        else
        {
            if (m_update_count == 0)
            {
                // First connection parameter update
                timeout_ticks = m_conn_params_config.first_conn_params_update_delay;
            }
            else
            {
                timeout_ticks = m_conn_params_config.next_conn_params_update_delay;
            }

            err_code = app_timer_start(m_conn_params_timer_id, timeout_ticks, NULL);
            if ((err_code != NRF_SUCCESS) && (m_conn_params_config.error_handler != NULL))
            {
                m_conn_params_config.error_handler(err_code);
            }
        }
    }
    else
    {
        // Notify the application that the procedure has succeeded
        if (m_conn_params_config.evt_handler != NULL)
        {
            ble_conn_params_evt_t evt;

            evt.evt_type = BLE_CONN_PARAMS_EVT_SUCCEEDED;
            m_conn_params_config.evt_handler(&evt);
        }
    }
    m_change_param = false;
}


static void on_connect(ble_evt_t * p_ble_evt)
{
    // Save connection parameters
    m_conn_handle         = p_ble_evt->evt.gap_evt.conn_handle;
    m_current_conn_params = p_ble_evt->evt.gap_evt.params.connected.conn_params;
    m_update_count        = 0;  // Connection parameter negotiation should re-start every connection

    // Check if we shall handle negotiation on connect
    if (m_conn_params_config.start_on_notify_cccd_handle == BLE_GATT_HANDLE_INVALID)
    {
        conn_params_negotiation();
    }
}


static void on_disconnect(ble_evt_t * p_ble_evt)
{
    uint32_t err_code;

    m_conn_handle = BLE_CONN_HANDLE_INVALID;

    // Stop timer if running
    m_update_count = 0; // Connection parameters updates should happen during every connection

    err_code = app_timer_stop(m_conn_params_timer_id);
    if ((err_code != NRF_SUCCESS) && (m_conn_params_config.error_handler != NULL))
    {
        m_conn_params_config.error_handler(err_code);
    }
}


static void on_write(ble_evt_t * p_ble_evt)
{
    ble_gatts_evt_write_t * p_evt_write = &p_ble_evt->evt.gatts_evt.params.write;

    // Check if this the correct CCCD
    if (
        (p_evt_write->handle == m_conn_params_config.start_on_notify_cccd_handle)
        &&
        (p_evt_write->len == 2)
       )
    {
        // Check if this is a 'start notification'
        if (ble_srv_is_notification_enabled(p_evt_write->data))
        {
            // Do connection parameter negotiation if necessary
            conn_params_negotiation();
        }
        else
        {
            uint32_t err_code;

            // Stop timer if running
            err_code = app_timer_stop(m_conn_params_timer_id);
            if ((err_code != NRF_SUCCESS) && (m_conn_params_config.error_handler != NULL))
            {
                m_conn_params_config.error_handler(err_code);
            }
        }
    }
}


static void on_conn_params_update(ble_evt_t * p_ble_evt)
{
    // Copy the parameters
    m_current_conn_params = p_ble_evt->evt.gap_evt.params.conn_param_update.conn_params;

    conn_params_negotiation();
}


void ble_conn_params_on_ble_evt(ble_evt_t * p_ble_evt)
{
    switch (p_ble_evt->header.evt_id)
    {
        case BLE_GAP_EVT_CONNECTED:
            on_connect(p_ble_evt);
            break;

        case BLE_GAP_EVT_DISCONNECTED:
            on_disconnect(p_ble_evt);
            break;

        case BLE_GATTS_EVT_WRITE:
            on_write(p_ble_evt);
            break;

        case BLE_GAP_EVT_CONN_PARAM_UPDATE:
            on_conn_params_update(p_ble_evt);
            break;

        default:
            // No implementation needed.
            break;
    }
}


uint32_t ble_conn_params_change_conn_params(ble_gap_conn_params_t * new_params)
{
    uint32_t err_code;

    m_preferred_conn_params = *new_params;
    // Set the connection params in stack
    err_code = sd_ble_gap_ppcp_set(&m_preferred_conn_params);
    if (err_code == NRF_SUCCESS)
    {
        if (!is_conn_params_ok(&m_current_conn_params))
        {
            m_change_param = true;
            err_code = sd_ble_gap_conn_param_update(m_conn_handle, &m_preferred_conn_params);
            m_update_count = 1;
        }
        else
        {
            // Notify the application that the procedure has succeded
            if (m_conn_params_config.evt_handler != NULL)
            {
                ble_conn_params_evt_t evt;

                evt.evt_type = BLE_CONN_PARAMS_EVT_SUCCEEDED;
                m_conn_params_config.evt_handler(&evt);
            }
            err_code = NRF_SUCCESS;
        }
    }
    return err_code;
}