Low power BLE Stack

RE: Low power BLE Stack

haakonsh — Thu, 17 Jan 2019 10:37:21 GMT

"is there any other way to control the power"

Not really, the only way to reduce the radios current consumption during transmission is to lower the output power, but that is usually not helpful as it will probably cause a greater number of packet loss who in turn cause more energy to be used to transmit your information.

"how this advertising works. how much power will constrain?"

It is described by the online power profiler.

"how to save the last paired device mac address"

See Peer Manager documentation.

"And it has to connect to the mobile phone without advertising."

That not possible. One of the devices has to advertise and the other has to listen for advertisements in order to establish a connection.

RE: Low power BLE Stack

Sunil vignesh — Tue, 15 Jan 2019 16:29:50 GMT

HI,

but in my case

my code work in LDO power rate is 8.30mA

and if it in DCDC power rate is 5.02mA

is there any other way to control the power

1. how this advertising works. how much power will constrain?

2. how to save the last paired device mac address. and it has to connect to the mobile phone without advertising.

means Bluetooth headphone connection process

when button is pressed for 7 seconds. it has to entered in advertising mode and advertise the device to near mobile phone.

then after connect with the mobile phone. it will memories the paired device

after disconnect with mobile phone. and restart the device while pressing the button for 2 seconds it has to ON the device and able to connect with last paired phone

is it possible with device

or any other way to connect automatically with mobile phone ..

RE: Low power BLE Stack

haakonsh — Tue, 15 Jan 2019 13:21:22 GMT

"which one i need to consider Green mark or Red mark .."

Both the average value and the actual waveform with sleep and peak currents are of interest.

"How to cut down it into less than 1mA"

The average current is already way below 1mA. There's nothing you can do about the peak currents. They are listed in the Product Specifications.
The SoftDevice are optimized so that the CPU and RADIO are not running at the same time in order to reduce the peak currents.

"but i need it to be in 0.8mA to 1mA for battery life extension ."
No BLE radio on the market can achieve peaks currents that low, even at minimum tx power. As an average current consumption for your use case that should not be a problem at all.

"how to access Tx power RX power control"
Tx power control is described in numerous posts on devzone.

RE: Low power BLE Stack

Sunil vignesh — Sat, 12 Jan 2019 04:59:07 GMT

can you tell me how to use online power profiling

details that i given above..

RE: Low power BLE Stack

haakonsh — Tue, 08 Jan 2019 08:52:36 GMT

Correction: The nRF52810 is the only nRF52 series SoC that does not have a CPU cache (to this date).

RE: Low power BLE Stack

awneil — Mon, 07 Jan 2019 16:41:44 GMT

[quote userid="74103" url="~/f/nordic-q-a/42182/low-power-ble-stack/164339"]how to access Tx power RX power control[/quote]

Review the SDK documentation!

You can't control the "Rx Power" - you receive whatever you receive!

RE: Low power BLE Stack

natersoz — Mon, 07 Jan 2019 16:02:27 GMT

This CPU has no cache. One less thing to worry about.

RE: Low power BLE Stack

Sunil vignesh — Mon, 07 Jan 2019 15:52:36 GMT

Hi,

Thank you.,

bu seen online power profiling..

https://devzone.nordicsemi.com/power/

which one i need to consider Green mark or Red mark ..

How to cut down it into less than 1mA

Is there any document or video tutorial related to power profiling.

why i try to do is the following code continuously read the sensor data for every one second and broadcast to mobile phone .

if it work in LDO power rate is 8.30mA

and if it in DCDC power rate is 5.02mA

but i need it to be in 0.8mA to 1mA for battery life extension . what i want to do

how to access Tx power RX power control, CPU CACHE, every thing

can you guide me

#include <stdio.h>
#include <stdint.h>
#include <string.h>
#include "nordic_common.h"
#include "nrf.h"
#include "ble_hci.h"
#include "ble_advdata.h"
#include "ble_advertising.h"
#include "ble_conn_params.h"
#include "nrf_sdh.h"
#include "nrf_sdh_soc.h"
#include "nrf_sdh_ble.h"
#include "nrf_ble_gatt.h"
#include "nrf_ble_qwr.h"
#include "app_timer.h"
#include "ble_nus.h"
#include "app_uart.h"
#include "app_util_platform.h"
#include "bsp_btn_ble.h"
#include "nrf_pwr_mgmt.h"
#include "nrf_drv_twi.h"
#include "nrf_delay.h"
#include "app_button.h"

#if defined (UART_PRESENT)
#include "nrf_uart.h"
#endif
#if defined (UARTE_PRESENT)
#include "nrf_uarte.h"
#endif

#include "nrf_log.h"
#include "nrf_log_ctrl.h"
#include "nrf_log_default_backends.h"

#include "bmi160.h"

/* TWI instance ID. */
#define TWI_INSTANCE_ID     0

#define G_TO_LSB (16384.0f)
#define PI (3.14159)

#define DPS_TO_LSB (131.072f)

#define ADVERTISING_LED                 BSP_BOARD_LED_0                         /**< Is on when device is advertising. */
#define CONNECTED_LED                   BSP_BOARD_LED_1                         /**< Is on when device has connected. */
#define LEDBUTTON_LED                   BSP_BOARD_LED_2                         /**< LED to be toggled with the help of the LED Button Service. */
#define LEDBUTTON_BUTTON                BSP_BUTTON_0                            /**< Button that will trigger the notification event with the LED Button Service */


#define APP_BLE_CONN_CFG_TAG            1                                           /**< A tag identifying the SoftDevice BLE configuration. */

#define DEVICE_NAME                     "L-SPoT_fw_v1.1"                               /**< Name of device. Will be included in the advertising data. */
#define NUS_SERVICE_UUID_TYPE           BLE_UUID_TYPE_VENDOR_BEGIN                  /**< UUID type for the Nordic UART Service (vendor specific). */

#define APP_BLE_OBSERVER_PRIO           3                                           /**< Application's BLE observer priority. You shouldn't need to modify this value. */

#define APP_ADV_INTERVAL                64                                          /**< The advertising interval (in units of 0.625 ms. This value corresponds to 40 ms). */

#define APP_ADV_DURATION                BLE_GAP_ADV_TIMEOUT_GENERAL_UNLIMITED   /**< The advertising time-out (in units of seconds). When set to 0, we will never time out. */

//#define APP_ADV_DURATION                18000                                       /**< The advertising duration (180 seconds) in units of 10 milliseconds. */

#define MIN_CONN_INTERVAL               MSEC_TO_UNITS(20, UNIT_1_25_MS)             /**< Minimum acceptable connection interval (20 ms), Connection interval uses 1.25 ms units. */
#define MAX_CONN_INTERVAL               MSEC_TO_UNITS(75, UNIT_1_25_MS)             /**< Maximum acceptable connection interval (75 ms), Connection interval uses 1.25 ms units. */
#define SLAVE_LATENCY                   0                                           /**< Slave latency. */
#define CONN_SUP_TIMEOUT                MSEC_TO_UNITS(4000, UNIT_10_MS)             /**< Connection supervisory timeout (4 seconds), Supervision Timeout uses 10 ms units. */
#define FIRST_CONN_PARAMS_UPDATE_DELAY  APP_TIMER_TICKS(5000)                       /**< Time from initiating event (connect or start of notification) to first time sd_ble_gap_conn_param_update is called (5 seconds). */
#define NEXT_CONN_PARAMS_UPDATE_DELAY   APP_TIMER_TICKS(30000)                      /**< Time between each call to sd_ble_gap_conn_param_update after the first call (30 seconds). */
#define MAX_CONN_PARAMS_UPDATE_COUNT    3                                           /**< Number of attempts before giving up the connection parameter negotiation. */

#define DEAD_BEEF                       0xDEADBEEF                                  /**< Value used as error code on stack dump, can be used to identify stack location on stack unwind. */
#define BUTTON_DETECTION_DELAY          APP_TIMER_TICKS(50)                     /**< Delay from a GPIOTE event until a button is reported as pushed (in number of timer ticks). */
#define UART_TX_BUF_SIZE                256                                         /**< UART TX buffer size. */
#define UART_RX_BUF_SIZE                256                                         /**< UART RX buffer size. */

/* Indicates if operation on TWI has ended. */
static volatile bool m_xfer_done = false;

/* TWI instance. */
static const nrf_drv_twi_t m_twi = NRF_DRV_TWI_INSTANCE(TWI_INSTANCE_ID);
/* BMI_160. */
struct bmi160_dev sensor;
struct bmi160_sensor_data accel;
struct bmi160_sensor_data gyro;

APP_TIMER_DEF(sensor_handle); // timer a

int8_t rslt = BMI160_OK;
int8_t rsltr = BMI160_OK;
int8_t rsltw = BMI160_OK;
int8_t rsltb = BMI160_OK;

bool ble_flag = false;
bool cali_flag = false;

float valx, valy, valz;
int accx, accy, accz, calib;
char str[80];
uint16_t length1;
ret_code_t rssi;


BLE_NUS_DEF(m_nus, NRF_SDH_BLE_TOTAL_LINK_COUNT);                                   /**< BLE NUS service instance. */
NRF_BLE_GATT_DEF(m_gatt);                                                           /**< GATT module instance. */
NRF_BLE_QWR_DEF(m_qwr);                                                             /**< Context for the Queued Write module.*/
BLE_ADVERTISING_DEF(m_advertising);                                                 /**< Advertising module instance. */

static uint16_t   m_conn_handle          = BLE_CONN_HANDLE_INVALID;                 /**< Handle of the current connection. */
static uint16_t   m_ble_nus_max_data_len = BLE_GATT_ATT_MTU_DEFAULT - 3;            /**< Maximum length of data (in bytes) that can be transmitted to the peer by the Nordic UART service module. */
static ble_uuid_t m_adv_uuids[]          =                                          /**< Universally unique service identifier. */
{
    {BLE_UUID_NUS_SERVICE, NUS_SERVICE_UUID_TYPE}
};

/**@brief Function for assert macro callback.
 *
 * @details This function will be called in case of an assert in the SoftDevice.
 *
 * @warning This handler is an example only and does not fit a final product. You need to analyse
 *          how your product is supposed to react in case of Assert.
 * @warning On assert from the SoftDevice, the system can only recover on reset.
 *
 * @param[in] line_num    Line number of the failing ASSERT call.
 * @param[in] p_file_name File name of the failing ASSERT call.
 */
void assert_nrf_callback(uint16_t line_num, const uint8_t * p_file_name)
{
    app_error_handler(DEAD_BEEF, line_num, p_file_name);
}


/**@brief Function for handling the data from the Nordic UART Service.
 *
 * @details This function will process the data received from the Nordic UART BLE Service and send
 *          it to the UART module.
 *
 * @param[in] p_evt       Nordic UART Service event.
 */
/**@snippet [Handling the data received over BLE] */
static void nus_data_handler(ble_nus_evt_t * p_evt)
{

    if (p_evt->type == BLE_NUS_EVT_RX_DATA)
    {
        uint32_t err_code;

        NRF_LOG_DEBUG("Received data from BLE NUS. Writing data on UART.");
        NRF_LOG_HEXDUMP_DEBUG(p_evt->params.rx_data.p_data, p_evt->params.rx_data.length);

        for (uint32_t i = 0; i < p_evt->params.rx_data.length; i++)
        {
            do
            {
                err_code = app_uart_put(p_evt->params.rx_data.p_data[i]);
                if ((err_code != NRF_SUCCESS) && (err_code != NRF_ERROR_BUSY))
                {
                    NRF_LOG_ERROR("Failed receiving NUS message. Error 0x%x. ", err_code);
                    APP_ERROR_CHECK(err_code);
                }
            } while (err_code == NRF_ERROR_BUSY);
        }
        if (p_evt->params.rx_data.p_data[p_evt->params.rx_data.length - 1] == '\r')
        {
            while (app_uart_put('\n') == NRF_ERROR_BUSY);
        }
    }

}
/**@snippet [Handling the data received over BLE] */



/**@brief   Function for handling app_uart events.
 *
 * @details This function will receive a single character from the app_uart module and append it to
 *          a string. The string will be be sent over BLE when the last character received was a
 *          'new line' '\n' (hex 0x0A) or if the string has reached the maximum data length.
 */
/**@snippet [Handling the data received over UART] */
void uart_event_handle(app_uart_evt_t * p_event)
{
    static uint8_t data_array[BLE_NUS_MAX_DATA_LEN];
    static uint8_t index = 0;
    uint32_t       err_code;

    switch (p_event->evt_type)
    {
        case APP_UART_DATA_READY:
            UNUSED_VARIABLE(app_uart_get(&data_array[index]));
            index++;

            if ((data_array[index - 1] == '\n') ||
                (data_array[index - 1] == '\r') ||
                (index >= m_ble_nus_max_data_len))
            {
                if (index > 1)
                {
                    NRF_LOG_DEBUG("Ready to send data over BLE NUS");
                    NRF_LOG_HEXDUMP_DEBUG(data_array, index);

                    do
                    {
                        uint16_t length = (uint16_t)index;
                        err_code = ble_nus_data_send(&m_nus, data_array, &length, m_conn_handle);
                        if ((err_code != NRF_ERROR_INVALID_STATE) &&
                            (err_code != NRF_ERROR_RESOURCES) &&
                            (err_code != NRF_ERROR_NOT_FOUND))
                        {
                            APP_ERROR_CHECK(err_code);
                        }
                    } while (err_code == NRF_ERROR_RESOURCES);
                }

                index = 0;
            }
            break;

        case APP_UART_COMMUNICATION_ERROR:
            APP_ERROR_HANDLER(p_event->data.error_communication);
            break;

        case APP_UART_FIFO_ERROR:
            APP_ERROR_HANDLER(p_event->data.error_code);
            break;

        default:
            break;
    }
}
/**@snippet [Handling the data received over UART] */



/**@brief  Function for initializing the UART module.
 */
/**@snippet [UART Initialization] */
static void uart_init(void)
{
    uint32_t                     err_code;
    app_uart_comm_params_t const comm_params =
    {
        .rx_pin_no    = RX_PIN_NUMBER,
        .tx_pin_no    = TX_PIN_NUMBER,
        .rts_pin_no   = RTS_PIN_NUMBER,
        .cts_pin_no   = CTS_PIN_NUMBER,
        .flow_control = APP_UART_FLOW_CONTROL_DISABLED,
        .use_parity   = false,
#if defined (UART_PRESENT)
        .baud_rate    = NRF_UART_BAUDRATE_115200
#else
        .baud_rate    = NRF_UARTE_BAUDRATE_115200
#endif
    };

    APP_UART_FIFO_INIT(&comm_params,
                       UART_RX_BUF_SIZE,
                       UART_TX_BUF_SIZE,
                       uart_event_handle,
                       APP_IRQ_PRIORITY_LOWEST,
                       err_code);
    APP_ERROR_CHECK(err_code);
}
/**@snippet [UART Initialization] */




/**@brief Function for the LEDs initialization.
 *
 * @details Initializes all LEDs used by the application.
 */
static void leds_init(void)
{
    bsp_board_init(BSP_INIT_LEDS);
}



/**@brief Function for initializing the timer module.
 */
static void timers_init(void)
{
    ret_code_t err_code = app_timer_init();
    APP_ERROR_CHECK(err_code);
}

/**@brief Function for the GAP initialization.
 *
 * @details This function will set up all the necessary GAP (Generic Access Profile) parameters of
 *          the device. It also sets the permissions and appearance.
 */
static void gap_params_init(void)
{
    uint32_t                err_code;
    ble_gap_conn_params_t   gap_conn_params;
    ble_gap_conn_sec_mode_t sec_mode;

    BLE_GAP_CONN_SEC_MODE_SET_OPEN(&sec_mode);

    err_code = sd_ble_gap_device_name_set(&sec_mode,
                                          (const uint8_t *) DEVICE_NAME,
                                          strlen(DEVICE_NAME));
    APP_ERROR_CHECK(err_code);

    memset(&gap_conn_params, 0, sizeof(gap_conn_params));

    gap_conn_params.min_conn_interval = MIN_CONN_INTERVAL;
    gap_conn_params.max_conn_interval = MAX_CONN_INTERVAL;
    gap_conn_params.slave_latency     = SLAVE_LATENCY;
    gap_conn_params.conn_sup_timeout  = CONN_SUP_TIMEOUT;

    err_code = sd_ble_gap_ppcp_set(&gap_conn_params);
    APP_ERROR_CHECK(err_code);
}


/**@brief Function for handling Queued Write Module errors.
 *
 * @details A pointer to this function will be passed to each service which may need to inform the
 *          application about an error.
 *
 * @param[in]   nrf_error   Error code containing information about what went wrong.
 */
static void nrf_qwr_error_handler(uint32_t nrf_error)
{
    APP_ERROR_HANDLER(nrf_error);
}


/**@brief Function for initializing services that will be used by the application.
 */
static void services_init(void)
{
    uint32_t           err_code;
    ble_nus_init_t     nus_init;
    nrf_ble_qwr_init_t qwr_init = {0};

    // Initialize Queued Write Module.
    qwr_init.error_handler = nrf_qwr_error_handler;

    err_code = nrf_ble_qwr_init(&m_qwr, &qwr_init);
    APP_ERROR_CHECK(err_code);

    // Initialize NUS.
    memset(&nus_init, 0, sizeof(nus_init));

    nus_init.data_handler = nus_data_handler;

    err_code = ble_nus_init(&m_nus, &nus_init);
    APP_ERROR_CHECK(err_code);
}


/**@brief Function for handling an event from the Connection Parameters Module.
 *
 * @details This function will be called for all events in the Connection Parameters Module
 *          which are passed to the application.
 *
 * @note All this function does is to disconnect. This could have been done by simply setting
 *       the disconnect_on_fail config parameter, but instead we use the event handler
 *       mechanism to demonstrate its use.
 *
 * @param[in] p_evt  Event received from the Connection Parameters Module.
 */
static void on_conn_params_evt(ble_conn_params_evt_t * p_evt)
{
    uint32_t err_code;

    if (p_evt->evt_type == BLE_CONN_PARAMS_EVT_FAILED)
    {
        err_code = sd_ble_gap_disconnect(m_conn_handle, BLE_HCI_CONN_INTERVAL_UNACCEPTABLE);
        APP_ERROR_CHECK(err_code);
    }
}


/**@brief Function for handling errors from the Connection Parameters module.
 *
 * @param[in] nrf_error  Error code containing information about what went wrong.
 */
static void conn_params_error_handler(uint32_t nrf_error)
{
    APP_ERROR_HANDLER(nrf_error);
}


/**@brief Function for initializing the Connection Parameters module.
 */
static void conn_params_init(void)
{
    uint32_t               err_code;
    ble_conn_params_init_t cp_init;

    memset(&cp_init, 0, sizeof(cp_init));

    cp_init.p_conn_params                  = NULL;
    cp_init.first_conn_params_update_delay = FIRST_CONN_PARAMS_UPDATE_DELAY;
    cp_init.next_conn_params_update_delay  = NEXT_CONN_PARAMS_UPDATE_DELAY;
    cp_init.max_conn_params_update_count   = MAX_CONN_PARAMS_UPDATE_COUNT;
    cp_init.start_on_notify_cccd_handle    = BLE_GATT_HANDLE_INVALID;
    cp_init.disconnect_on_fail             = false;
    cp_init.evt_handler                    = on_conn_params_evt;
    cp_init.error_handler                  = conn_params_error_handler;

    err_code = ble_conn_params_init(&cp_init);
    APP_ERROR_CHECK(err_code);
}


/**@brief Function for putting the chip into sleep mode.
 *
 * @note This function will not return.
 */
static void sleep_mode_enter(void)
{
    uint32_t err_code = bsp_indication_set(BSP_INDICATE_IDLE);
    APP_ERROR_CHECK(err_code);

    // Prepare wakeup buttons.
    err_code = bsp_btn_ble_sleep_mode_prepare();
    APP_ERROR_CHECK(err_code);

    // Go to system-off mode (this function will not return; wakeup will cause a reset).
    err_code = sd_power_system_off();
    APP_ERROR_CHECK(err_code);
}


/**@brief Function for handling advertising events.
 *
 * @details This function will be called for advertising events which are passed to the application.
 *
 * @param[in] ble_adv_evt  Advertising event.
 */
static void on_adv_evt(ble_adv_evt_t ble_adv_evt)
{
    uint32_t err_code;

    switch (ble_adv_evt)
    {
        case BLE_ADV_EVT_FAST:
            err_code = bsp_indication_set(BSP_INDICATE_ADVERTISING);
            APP_ERROR_CHECK(err_code);
            break;
        case BLE_ADV_EVT_IDLE:
            sleep_mode_enter();
            break;
        default:
            break;
    }
}


/**@brief Function for handling BLE events.
 *
 * @param[in]   p_ble_evt   Bluetooth stack event.
 * @param[in]   p_context   Unused.
 */
static void ble_evt_handler(ble_evt_t const * p_ble_evt, void * p_context)
{
    uint32_t err_code;

    switch (p_ble_evt->header.evt_id)
    {
        case BLE_GAP_EVT_CONNECTED:
            NRF_LOG_INFO("Connected");
           // bsp_board_led_on(CONNECTED_LED);
            err_code = bsp_indication_set(BSP_INDICATE_CONNECTED);
            APP_ERROR_CHECK(err_code);
            m_conn_handle = p_ble_evt->evt.gap_evt.conn_handle;
            err_code = nrf_ble_qwr_conn_handle_assign(&m_qwr, m_conn_handle);
            APP_ERROR_CHECK(err_code);

            err_code = app_button_enable();
            APP_ERROR_CHECK(err_code);
            err_code = sd_ble_gap_rssi_start(m_conn_handle, 1, 1);
            APP_ERROR_CHECK(err_code);
            ble_flag = true;
            break;

         case BLE_GAP_EVT_RSSI_CHANGED:
           // NRF_LOG_INFO("RSSI: %d dBm", p_ble_evt->evt.gap_evt.params.rssi_changed.rssi);
           // printf("RSSI: %d dBm\r\n", p_ble_evt->evt.gap_evt.params.rssi_changed.rssi);
            rssi = p_ble_evt->evt.gap_evt.params.rssi_changed.rssi;

            break;

        case BLE_GAP_EVT_DISCONNECTED:
            NRF_LOG_INFO("Disconnected");
           // bsp_board_led_off(CONNECTED_LED);
            // LED indication will be changed when advertising starts.
            m_conn_handle = BLE_CONN_HANDLE_INVALID;
            err_code = app_button_disable();
            APP_ERROR_CHECK(err_code);
            ble_flag = false;
            //advertising_start();
            break;

        case BLE_GAP_EVT_PHY_UPDATE_REQUEST:
        {
            NRF_LOG_DEBUG("PHY update request.");
            ble_gap_phys_t const phys =
            {
                .rx_phys = BLE_GAP_PHY_AUTO,
                .tx_phys = BLE_GAP_PHY_AUTO,
            };
            err_code = sd_ble_gap_phy_update(p_ble_evt->evt.gap_evt.conn_handle, &phys);
            APP_ERROR_CHECK(err_code);
        } break;

        case BLE_GAP_EVT_SEC_PARAMS_REQUEST:
            // Pairing not supported
            err_code = sd_ble_gap_sec_params_reply(m_conn_handle, BLE_GAP_SEC_STATUS_PAIRING_NOT_SUPP, NULL, NULL);
            APP_ERROR_CHECK(err_code);
            break;

        case BLE_GATTS_EVT_SYS_ATTR_MISSING:
            // No system attributes have been stored.
            err_code = sd_ble_gatts_sys_attr_set(m_conn_handle, NULL, 0, 0);
            APP_ERROR_CHECK(err_code);
            break;

        case BLE_GATTC_EVT_TIMEOUT:
            // Disconnect on GATT Client timeout event.
            NRF_LOG_DEBUG("GATT Client Timeout.");
            err_code = sd_ble_gap_disconnect(p_ble_evt->evt.gattc_evt.conn_handle,
                                             BLE_HCI_REMOTE_USER_TERMINATED_CONNECTION);
            APP_ERROR_CHECK(err_code);
            break;

        case BLE_GATTS_EVT_TIMEOUT:
            // Disconnect on GATT Server timeout event.
            NRF_LOG_DEBUG("GATT Server Timeout.");
            err_code = sd_ble_gap_disconnect(p_ble_evt->evt.gatts_evt.conn_handle,
                                             BLE_HCI_REMOTE_USER_TERMINATED_CONNECTION);
            APP_ERROR_CHECK(err_code);
            break;

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


/**@brief Function for the SoftDevice initialization.
 *
 * @details This function initializes the SoftDevice and the BLE event interrupt.
 */
static void ble_stack_init(void)
{
    ret_code_t err_code;

    err_code = nrf_sdh_enable_request();
    APP_ERROR_CHECK(err_code);

    // Configure the BLE stack using the default settings.
    // Fetch the start address of the application RAM.
    uint32_t ram_start = 0;
    err_code = nrf_sdh_ble_default_cfg_set(APP_BLE_CONN_CFG_TAG, &ram_start);
    APP_ERROR_CHECK(err_code);

    // Enable BLE stack.
    err_code = nrf_sdh_ble_enable(&ram_start);
    APP_ERROR_CHECK(err_code);

    // Register a handler for BLE events.
    NRF_SDH_BLE_OBSERVER(m_ble_observer, APP_BLE_OBSERVER_PRIO, ble_evt_handler, NULL);
}




/**@brief Function for handling events from the GATT library. */
void gatt_evt_handler(nrf_ble_gatt_t * p_gatt, nrf_ble_gatt_evt_t const * p_evt)
{
    if ((m_conn_handle == p_evt->conn_handle) && (p_evt->evt_id == NRF_BLE_GATT_EVT_ATT_MTU_UPDATED))
    {
        m_ble_nus_max_data_len = p_evt->params.att_mtu_effective - OPCODE_LENGTH - HANDLE_LENGTH;
        NRF_LOG_INFO("Data len is set to 0x%X(%d)", m_ble_nus_max_data_len, m_ble_nus_max_data_len);
    }
    NRF_LOG_DEBUG("ATT MTU exchange completed. central 0x%x peripheral 0x%x",
                  p_gatt->att_mtu_desired_central,
                  p_gatt->att_mtu_desired_periph);
}


/**@brief Function for initializing the GATT library. */
void gatt_init(void)
{
    ret_code_t err_code;

    err_code = nrf_ble_gatt_init(&m_gatt, gatt_evt_handler);
    APP_ERROR_CHECK(err_code);

    err_code = nrf_ble_gatt_att_mtu_periph_set(&m_gatt, NRF_SDH_BLE_GATT_MAX_MTU_SIZE);
    APP_ERROR_CHECK(err_code);
}


/**@brief Function for handling events from the BSP module.
 *
 * @param[in]   event   Event generated by button press.
 */
void bsp_event_handler(bsp_event_t event)
{
    uint32_t err_code;
    switch (event)
    {
        case BSP_EVENT_SLEEP:
            sleep_mode_enter();
            break;

        case BSP_EVENT_DISCONNECT:
            err_code = sd_ble_gap_disconnect(m_conn_handle, BLE_HCI_REMOTE_USER_TERMINATED_CONNECTION);
            if (err_code != NRF_ERROR_INVALID_STATE)
            {
                APP_ERROR_CHECK(err_code);
            }
            break;

        case BSP_EVENT_WHITELIST_OFF:
            if (m_conn_handle == BLE_CONN_HANDLE_INVALID)
            {
                err_code = ble_advertising_restart_without_whitelist(&m_advertising);
                if (err_code != NRF_ERROR_INVALID_STATE)
                {
                    APP_ERROR_CHECK(err_code);
                }
            }
            break;

        default:
            break;
    }
}


/**@brief Function for initializing the Advertising functionality.
 */
static void advertising_init(void)
{
    uint32_t               err_code;
    ble_advertising_init_t init;

    memset(&init, 0, sizeof(init));

    init.advdata.name_type          = BLE_ADVDATA_FULL_NAME;
    init.advdata.include_appearance = false;
    init.advdata.flags              = BLE_GAP_ADV_FLAGS_LE_ONLY_GENERAL_DISC_MODE;
//  init.advdata.flags              = BLE_GAP_ADV_FLAGS_LE_ONLY_LIMITED_DISC_MODE;

    init.srdata.uuids_complete.uuid_cnt = sizeof(m_adv_uuids) / sizeof(m_adv_uuids[0]);
    init.srdata.uuids_complete.p_uuids  = m_adv_uuids;

    init.config.ble_adv_fast_enabled  = true;
    init.config.ble_adv_fast_interval = APP_ADV_INTERVAL;
    init.config.ble_adv_fast_timeout  = APP_ADV_DURATION;
    init.evt_handler = on_adv_evt;

    err_code = ble_advertising_init(&m_advertising, &init);
    APP_ERROR_CHECK(err_code);

    ble_advertising_conn_cfg_tag_set(&m_advertising, APP_BLE_CONN_CFG_TAG);
}


/**@brief Function for initializing buttons and leds.
 *
 * @param[out] p_erase_bonds  Will be true if the clear bonding button was pressed to wake the application up.
 */

 
    


static void buttons_leds_init(bool * p_erase_bonds)
{
    bsp_event_t startup_event;

    uint32_t err_code = bsp_init(BSP_INIT_LEDS | BSP_INIT_BUTTONS, bsp_event_handler);
    APP_ERROR_CHECK(err_code);

    err_code = bsp_btn_ble_init(NULL, &startup_event);
    APP_ERROR_CHECK(err_code);

    *p_erase_bonds = (startup_event == BSP_EVENT_CLEAR_BONDING_DATA);
}


/**@brief Function for initializing the nrf log module.
 */
static void log_init(void)
{
    ret_code_t err_code = NRF_LOG_INIT(NULL);
    APP_ERROR_CHECK(err_code);

    NRF_LOG_DEFAULT_BACKENDS_INIT();
}


/**@brief Function for initializing power management.
 */
static void power_management_init(void)
{
    ret_code_t err_code;
    err_code = nrf_pwr_mgmt_init();
    APP_ERROR_CHECK(err_code);
}


/**@brief Function for handling the idle state (main loop).
 *
 * @details If there is no pending log operation, then sleep until next the next event occurs.
 */
static void idle_state_handle(void)
{
    UNUSED_RETURN_VALUE(NRF_LOG_PROCESS());
    nrf_pwr_mgmt_run();
}


/**@brief Function for starting advertising.
 */
static void advertising_start(void)
{
    uint32_t err_code = ble_advertising_start(&m_advertising, BLE_ADV_MODE_FAST);
    APP_ERROR_CHECK(err_code);
}



/*TWI initialization*/

void twi_init (void)
{
    ret_code_t err_code;

    const nrf_drv_twi_config_t twi_config = {
       .scl                = ARDUINO_SCL_PIN,
       .sda                = ARDUINO_SDA_PIN,
       .frequency          = NRF_DRV_TWI_FREQ_100K,
       .interrupt_priority = APP_IRQ_PRIORITY_HIGH,
       .clear_bus_init     = false
    };

    err_code = nrf_drv_twi_init(&m_twi, &twi_config, NULL, NULL);
    
    APP_ERROR_CHECK(err_code);
    if (NRF_SUCCESS == err_code)
	{
		nrf_drv_twi_enable(&m_twi);
		NRF_LOG_INFO("TWI init success...");	
	}
}

int8_t Acc_i2c_Write(uint8_t dev_id, uint8_t reg_addr, uint8_t *reg_data, uint16_t len)
{

    //  NRF_LOG_INFO("WRITE: dev_id: %x reg_addr: %x reg_data: %x len: %i\n", dev_id, reg_addr, *reg_data, len);
	//int8_t rslt = 0;
	uint8_t data[len + 1];
	data[0] = reg_addr;
	for (uint16_t i = 0; i < len; i++) {
		data[i + 1] = reg_data[i];
	}
	
	rsltw = nrf_drv_twi_tx(&m_twi, dev_id, data, len + 1, false);
	//APP_ERROR_CHECK(rsltw);
        return rsltw;
  
}


int8_t Acc_i2c_Read(uint8_t dev_id, uint8_t reg_addr, uint8_t *reg_data, uint16_t len)
{
	//int8_t rslt = 0;
   //     NRF_LOG_INFO("READ: dev_id: %x reg_addr: %x len: %i\n", dev_id, reg_addr, len);
	rsltr = nrf_drv_twi_tx(&m_twi, dev_id, &reg_addr, 1, true);
       // APP_ERROR_CHECK(rsltr);

	if (rsltr == 0)
	{
		rsltr = nrf_drv_twi_rx(&m_twi, dev_id, reg_data, len);
	}
    //    NRF_LOG_INFO("READ: %x",*reg_data);
	return rsltr;
}

void Acc_delay_ms(uint32_t period)
{ 
	
/*if (period==NULL){
period = 1;
}// delay time*/
	
  nrf_delay_ms( period ) ;
}


void BMI160_init (void)
{
    sensor.id = BMI160_I2C_ADDR;         //0x69
    sensor.interface = BMI160_I2C_INTF;  //0x00
    sensor.read = &Acc_i2c_Read;
    sensor.write = &Acc_i2c_Write;
    sensor.delay_ms = &Acc_delay_ms;

    rslt = bmi160_init(&sensor);
    APP_ERROR_CHECK(rslt);

    if(rslt == BMI160_OK){
    NRF_LOG_INFO("BMI160 Initialized...");
    } else {
    NRF_LOG_INFO("BMI160 not Initialized...");
    }//NRF_LOG_FLUSH();

    sensor.accel_cfg.odr = BMI160_ACCEL_ODR_12_5HZ;
    sensor.accel_cfg.range = BMI160_ACCEL_RANGE_2G;
    sensor.accel_cfg.bw = BMI160_ACCEL_BW_NORMAL_AVG4;
    sensor.accel_cfg.power = BMI160_ACCEL_LOWPOWER_MODE;

    sensor.gyro_cfg.odr = BMI160_GYRO_ODR_25HZ;
    sensor.gyro_cfg.range = BMI160_GYRO_RANGE_2000_DPS;
    sensor.gyro_cfg.bw = BMI160_GYRO_BW_NORMAL_MODE;
    sensor.gyro_cfg.power = BMI160_GYRO_NORMAL_MODE;

    rslt = bmi160_set_sens_conf(&sensor);
    APP_ERROR_CHECK(rslt);

     if(rslt == BMI160_OK){
    NRF_LOG_INFO("sensor Configured...");
    } else {
    NRF_LOG_INFO("sensor not Configured...");
    }//NRF_LOG_FLUSH();
}

 void vib()
{
    nrf_gpio_pin_write(17,1);
    nrf_delay_ms(80);
    nrf_gpio_pin_write(17,0);
    nrf_delay_ms(20);
}

static void read_sensor_data()
{
      m_xfer_done = false;
      int8_t note = 0;
          
      bmi160_get_sensor_data((BMI160_ACCEL_SEL | BMI160_GYRO_SEL | BMI160_TIME_SEL), &accel, &gyro, &sensor);

    /*  NRF_LOG_INFO("DataX:%d", accel.x);
      NRF_LOG_INFO("DataY:%d", accel.y);
      NRF_LOG_INFO("DataZ:%d", accel.z);
      NRF_LOG_INFO("GyroX:%d", gyro.x);
      NRF_LOG_INFO("GyroY:%d", gyro.y);
      NRF_LOG_INFO("GyroZ:%d", gyro.z);
       NRF_LOG_FLUSH();*/

     // float accelX = ((((float)accel.x) / G_TO_LSB) * 9.80655); // in m/s^2
      
       valx = ( (float)(accel.x - 265)*(1.31387)+(-270));
       valy = ( (float)(accel.y- 265)*(1.31387)+(-90));
       valz = ( (float)(accel.z - 265)*(1.31387)+(-90));
        
    // accelX = (atan2(accel.y,accel.z)*57.3);
    //  printf("\r\n m/s^2  : %.2f \r\n",accelX);
     // accelX = (atan2((-accel.x),sqrt((accel.y*accel.y)+(accel.z*accel.z)))*57.3);

       accx= (int)(atan2(-valy, -valz)*(180/PI));//angle of forward backward
       accy= (int)(atan2(-valx, -valz)*(180/PI));
       accz= (int)(atan2(-valy, -valx)*(180/PI));// angle of right left
       accx = abs(accx);

       if(cali_flag == true)
       {
        
          if (((calib - accx) >= 20) || ((accx - calib) >=30))
              {
                  note = 1;
                  vib();
              }

          else
             {
                note = 0;
             }
       }

       if ((ble_flag == true)&&(cali_flag == true))
       {
         
              length1 = sprintf(str, "*%d,%d,%d#\n", accx, note, rssi);
              rsltb = ble_nus_data_send(&m_nus, str, &length1, m_conn_handle);
              
       }
     NRF_LOG_INFO("angle_X:%d", accx);
     NRF_LOG_INFO("angle_Y:%d", accy);
     NRF_LOG_INFO("angle_Z:%d", accz);
      NRF_LOG_FLUSH();
     
}

 void calib_vib()
{
    nrf_gpio_pin_write(17,1);
    nrf_delay_ms(200);
    nrf_gpio_pin_write(17,0);
    nrf_delay_ms(100);
}
 void calibrate_init()
{
    nrf_gpio_pin_write(17,1);
    nrf_delay_ms(250);
    nrf_gpio_pin_write(17,0);
    nrf_delay_ms(150);
    nrf_gpio_pin_write(17,1);
    nrf_delay_ms(250);
    nrf_gpio_pin_write(17,0);
    nrf_delay_ms(50);
}

void calibration()
{
    int x = 1;
    for(x;x<=10;x++)
    {
        read_sensor_data();
        calib = calib + accx;
        calib_vib();
        NRF_LOG_INFO("count : %d ", x);
        NRF_LOG_FLUSH();
        nrf_delay_ms(1000);

    }

    calib = calib/10;
    NRF_LOG_INFO("calib : %d ", calib);
    cali_flag =  true;
    NRF_LOG_FLUSH();

}

/**@brief Application main function.
 */
int main(void)
{
    bool erase_bonds;
    uint8_t sample_data[10];

    // Initialize.
    uart_init();
    log_init();
    timers_init();
    buttons_leds_init(&erase_bonds);
    nrf_gpio_pin_dir_set(17, NRF_GPIO_PIN_DIR_OUTPUT);
    power_management_init();
    ble_stack_init();
    //uint32_t err_code = sd_power_dcdc_mode_set(NRF_POWER_DCDC_ENABLE);
   // APP_ERROR_CHECK(err_code);
    gap_params_init();
    gatt_init();
    services_init();
    advertising_init();
    conn_params_init();

    // Start execution.
    printf("\r\nUART started.\r\n");
    NRF_LOG_INFO("BMI160 get started...");
    advertising_start();
    Acc_delay_ms(100);

    twi_init();
    Acc_delay_ms(50);

    BMI160_init();
     NRF_LOG_FLUSH();
    Acc_delay_ms(100);
    calibrate_init();
    calibration();

    // Enter main loop.
    for (;;)
    {
        //idle_state_handle();
        nrf_delay_ms( 1000 ) ;
        read_sensor_data();
 
    }
}


/**
 * @}
 */

Thanks.,

RE: Low power BLE Stack

natersoz — Mon, 07 Jan 2019 00:10:09 GMT

Nice!

RE: Low power BLE Stack

rontec — Sun, 06 Jan 2019 22:22:18 GMT

Also see devzone.nordicsemi.com/.../

RE: Low power BLE Stack

natersoz — Sun, 06 Jan 2019 18:03:32 GMT

To even being to answer this question a person would need to know the connection interval, what sensors are enabled and when, what the advertising rate would be, what advertising duty cycle is required, etc.

As we used to say back when I was in school: "You're going to have to do you own homework".

A good place to start is the nrf52 Product Specification in their docs lib https://www.nordicsemi.com/DocLib

Chapter 19 is the Electrical Specification.

Literally Everything you need to know is right there.