Data Length Extension Issue

[willdavies]

I am writing an application on a BLE chip that will transmit high volumes of data to an Android phone (520,000 bytes / second signal).

According to some tests I've seen, I'm not going to get any where near 520,000 even with all optimizations on, but I'm getting really, really bad throughput right now, only about 600 bytes / second. I should be able to get this up to like 120,000 bytes per second right?

Okay, so I have a custom characteristic on my embedded chip, when the phone would like to take a reading, it writes to this characteristic. The chip will then respond with the 520,000 bytes / second signal by spamming sd_ble_gatts_hvx(p_cus->conn_handle, &hvx_params) 

#include <stdbool.h>
#include <stdint.h>
#include <string.h>

#include "nordic_common.h"
#include "nrf.h"
#include "app_error.h"
#include "ble.h"
#include "ble_hci.h"
#include "ble_srv_common.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 "app_timer.h"
#include "fds.h"
#include "peer_manager.h"
#include "peer_manager_handler.h"
#include "bsp_btn_ble.h"
#include "sensorsim.h"
#include "ble_conn_state.h"
#include "nrf_ble_gatt.h"
#include "nrf_ble_qwr.h"
#include "nrf_pwr_mgmt.h"

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

#define DEVICE_NAME "MagiCoil" /**< Name of device. Will be included in the advertising data. */
#define MANUFACTURER_NAME "NordicSemiconductor" /**< Manufacturer. Will be passed to Device Information Service. */
#define APP_ADV_INTERVAL 300 /**< The advertising interval (in units of 0.625 ms. This value corresponds to 187.5 ms). */

#define APP_ADV_DURATION 18000 /**< The advertising duration (180 seconds) in units of 10 milliseconds. */
#define APP_BLE_OBSERVER_PRIO 3 /**< Application's BLE observer priority. You shouldn't need to modify this value. */
#define APP_BLE_CONN_CFG_TAG 1 /**< A tag identifying the SoftDevice BLE configuration. */

#define CONN_INTERVAL_DEFAULT (uint16_t)(MSEC_TO_UNITS(7.5, UNIT_1_25_MS))
#define MIN_CONN_INTERVAL (uint16_t)(MSEC_TO_UNITS(7.5, UNIT_1_25_MS)) /**< Minimum acceptable connection interval, in units of 1.25 ms. */
#define MAX_CONN_INTERVAL (uint16_t)(MSEC_TO_UNITS(500, UNIT_1_25_MS)) /**< Maximum acceptable connection interval, in units of 1.25 ms. */
#define CONN_SUP_TIMEOUT (uint16_t)(MSEC_TO_UNITS(4000, UNIT_10_MS)) /**< Connection supervisory timeout (4 seconds). */
#define SLAVE_LATENCY 0

#define DATA_LENGTH_DEFAULT 27
#define DATA_LENGTH_MAX 251

#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 SEC_PARAM_BOND 1 /**< Perform bonding. */
#define SEC_PARAM_MITM 0 /**< Man In The Middle protection not required. */
#define SEC_PARAM_LESC 0 /**< LE Secure Connections not enabled. */
#define SEC_PARAM_KEYPRESS 0 /**< Keypress notifications not enabled. */
#define SEC_PARAM_IO_CAPABILITIES BLE_GAP_IO_CAPS_NONE /**< No I/O capabilities. */
#define SEC_PARAM_OOB 0 /**< Out Of Band data not available. */
#define SEC_PARAM_MIN_KEY_SIZE 7 /**< Minimum encryption key size. */
#define SEC_PARAM_MAX_KEY_SIZE 16 /**< Maximum encryption key size. */

#define DEAD_BEEF 0xDEADBEEF /**< Value used as error code on stack dump, can be used to identify stack location on stack unwind. */

NRF_BLE_GATT_DEF(m_gatt); /**< GATT module instance. */
NRF_BLE_QWR_DEF(m_qwr); /**< Context for the Queued Write module.*/
BLE_CUS_DEF(m_cus);
BLE_ADVERTISING_DEF(m_advertising); /**< Advertising module instance. */

static uint16_t m_conn_handle = BLE_CONN_HANDLE_INVALID; /**< Handle of the current connection. */

/* YOUR_JOB: Declare all services structure your application is using
* BLE_XYZ_DEF(m_xyz);
*/

// YOUR_JOB: Use UUIDs for service(s) used in your application.
static ble_uuid_t m_adv_uuids[] = /**< Universally unique service identifiers. */
{
{BLE_UUID_DEVICE_INFORMATION_SERVICE, BLE_UUID_TYPE_BLE}
};

static void advertising_start(bool erase_bonds);

/**@brief Callback function for asserts in the SoftDevice.
*
* @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 analyze
* 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] 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 Peer Manager events.
*
* @param[in] p_evt Peer Manager event.
*/
static void pm_evt_handler(pm_evt_t const * p_evt)
{
pm_handler_on_pm_evt(p_evt);
pm_handler_flash_clean(p_evt);

switch (p_evt->evt_id)
{
case PM_EVT_PEERS_DELETE_SUCCEEDED:
advertising_start(false);
break;

default:
break;
}
}

/**@brief Function for the Timer initialization.
*
* @details Initializes the timer module. This creates and starts application timers.
*/
static void timers_init(void)
{
// Initialize timer module.
ret_code_t err_code = app_timer_init();
APP_ERROR_CHECK(err_code);

// Create timers.

/* YOUR_JOB: Create any timers to be used by the application.
Below is an example of how to create a timer.
For every new timer needed, increase the value of the macro APP_TIMER_MAX_TIMERS by
one.
ret_code_t err_code;
err_code = app_timer_create(&m_app_timer_id, APP_TIMER_MODE_REPEATED, timer_timeout_handler);
APP_ERROR_CHECK(err_code); */
}

/**@brief Function for the GAP initialization.
*
* @details This function sets up all the necessary GAP (Generic Access Profile) parameters of the
* device including the device name, appearance, and the preferred connection parameters.
*/
static void gap_params_init(void)
{
ret_code_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);

/* YOUR_JOB: Use an appearance value matching the application's use case.
err_code = sd_ble_gap_appearance_set(BLE_APPEARANCE_);
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);
}

void gatt_evt_handler(nrf_ble_gatt_t * p_gatt, nrf_ble_gatt_evt_t const * p_evt)
{
if ((p_evt->evt_id == NRF_BLE_GATT_EVT_ATT_MTU_UPDATED))
{
printf("MTU size is set to %d", p_evt->params.att_mtu_effective);
}

if ( (p_evt->evt_id == NRF_BLE_GATT_EVT_DATA_LENGTH_UPDATED))
{
printf("LL packet size is set to %d", p_gatt->data_length);
}
}

/**@brief Function for initializing the GATT module.
*/
static void gatt_init(void)
{
ret_code_t err_code = nrf_ble_gatt_init(&m_gatt, gatt_evt_handler);
printf("GATT SUCCESS: %d\n",err_code);
APP_ERROR_CHECK(err_code);

//nrf_ble_gatt_data_length_set(&m_gatt, BLE_CONN_HANDLE_INVALID, 251);
nrf_ble_gatt_att_mtu_periph_set(&m_gatt, 247);
//nrf_ble_gatt_att_mtu_central_set(&m_gatt, 247);

}

/**@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 handling the YYY Service events.
* YOUR_JOB implement a service handler function depending on the event the service you are using can generate
*
* @details This function will be called for all YY Service events which are passed to
* the application.
*
* @param[in] p_yy_service YY Service structure.
* @param[in] p_evt Event received from the YY Service.
*
*
static void on_yys_evt(ble_yy_service_t * p_yy_service,
ble_yy_service_evt_t * p_evt)
{
switch (p_evt->evt_type)
{
case BLE_YY_NAME_EVT_WRITE:
APPL_LOG("[APPL]: charact written with value %s. ", p_evt->params.char_xx.value.p_str);
break;

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

static void on_cus_evt(ble_cus_t * p_cus_service,
ble_cus_evt_t * p_evt)
{

}

/**@brief Function for initializing services that will be used by the application.
*/
static void services_init(void)
{
ret_code_t err_code;
nrf_ble_qwr_init_t qwr_init = {0};
ble_cus_init_t cus_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 CUS Service init structure to zero.
cus_init.evt_handler = on_cus_evt;

BLE_GAP_CONN_SEC_MODE_SET_OPEN(&cus_init.custom_value_char_attr_md.cccd_write_perm);
BLE_GAP_CONN_SEC_MODE_SET_OPEN(&cus_init.custom_value_char_attr_md.read_perm);
BLE_GAP_CONN_SEC_MODE_SET_OPEN(&cus_init.custom_value_char_attr_md.write_perm);

err_code = ble_cus_init(&m_cus, &cus_init);
APP_ERROR_CHECK(err_code);

/* YOUR_JOB: Add code to initialize the services used by the application.
ble_xxs_init_t xxs_init;
ble_yys_init_t yys_init;

// Initialize XXX Service.
memset(&xxs_init, 0, sizeof(xxs_init));

xxs_init.evt_handler = NULL;
xxs_init.is_xxx_notify_supported = true;
xxs_init.ble_xx_initial_value.level = 100;

err_code = ble_bas_init(&m_xxs, &xxs_init);
APP_ERROR_CHECK(err_code);

// Initialize YYY Service.
memset(&yys_init, 0, sizeof(yys_init));
yys_init.evt_handler = on_yys_evt;
yys_init.ble_yy_initial_value.counter = 0;

err_code = ble_yy_service_init(&yys_init, &yy_init);
APP_ERROR_CHECK(err_code);
*/
}

/**@brief Function for handling 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)
{
ret_code_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 a Connection Parameters error.
*
* @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)
{
ret_code_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 starting timers.
*/
static void application_timers_start(void)
{
/* YOUR_JOB: Start your timers. below is an example of how to start a timer.
ret_code_t err_code;
err_code = app_timer_start(m_app_timer_id, TIMER_INTERVAL, NULL);
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)
{
ret_code_t err_code;

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)
{
ret_code_t err_code;

switch (ble_adv_evt)
{
case BLE_ADV_EVT_FAST:
NRF_LOG_INFO("Fast advertising.");
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)
{
ret_code_t err_code = NRF_SUCCESS;

switch (p_ble_evt->header.evt_id)
{
case BLE_GAP_EVT_DISCONNECTED:
NRF_LOG_INFO("Disconnected.");
// LED indication will be changed when advertising starts.
break;

case BLE_GAP_EVT_CONNECTED:
NRF_LOG_INFO("Connected.");

ble_gap_evt_t const * p_gap_evt = &p_ble_evt->evt.gap_evt;
m_conn_handle = p_ble_evt->evt.gap_evt.conn_handle;

sd_ble_gap_phy_update(p_gap_evt->conn_handle, BLE_GAP_PHY_2MBPS | BLE_GAP_PHY_1MBPS);

/*err_code = bsp_indication_set(BSP_INDICATE_CONNECTED);
APP_ERROR_CHECK(err_code);

err_code = nrf_ble_qwr_conn_handle_assign(&m_qwr, m_conn_handle);
APP_ERROR_CHECK(err_code);

//err_code = nrf_ble_gatt_data_length_set(&m_gatt, BLE_CONN_HANDLE_INVALID, 244);
//printf("data_length update code: %d",err_code);*/

break;
case BLE_GATTS_EVT_EXCHANGE_MTU_REQUEST:
printf("mtu request\n");
sd_ble_gatts_exchange_mtu_reply(p_ble_evt->evt.gap_evt.conn_handle, 247);
break;
case BLE_GAP_EVT_CONN_PARAM_UPDATE_REQUEST:
{
ble_gap_conn_params_t params;
params = p_gap_evt->params.conn_param_update_request.conn_params;
err_code = sd_ble_gap_conn_param_update(p_gap_evt->conn_handle, &params);
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;
case BLE_GAP_EVT_PHY_UPDATE_REQUEST:
err_code = sd_ble_gap_phy_update(p_gap_evt->conn_handle, BLE_GAP_PHY_2MBPS | BLE_GAP_PHY_1MBPS);
break;
default:
// No implementation needed.
break;
}
}
void data_len_set(uint8_t value)
{
ret_code_t err_code;
err_code = nrf_ble_gatt_data_length_set(&m_gatt, BLE_CONN_HANDLE_INVALID, value);
printf("Updating length: %d",err_code);
APP_ERROR_CHECK(err_code);
}

/**@brief Function for initializing the BLE stack.
*
* @details 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);
printf("defaults: %d\n",err_code);
//APP_ERROR_CHECK(err_code);

// Update perhiperal

// 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);

}

void gatt_mtu_set(uint16_t att_mtu)
{
ret_code_t err_code;

//m_test_params.att_mtu = att_mtu;

err_code = nrf_ble_gatt_att_mtu_periph_set(&m_gatt, att_mtu);
APP_ERROR_CHECK(err_code);

//err_code = nrf_ble_gatt_att_mtu_central_set(&m_gatt, att_mtu);
//APP_ERROR_CHECK(err_code);
}

/**@brief Function for the Peer Manager initialization.
*/
static void peer_manager_init(void)
{
ble_gap_sec_params_t sec_param;
ret_code_t err_code;

err_code = pm_init();
APP_ERROR_CHECK(err_code);

memset(&sec_param, 0, sizeof(ble_gap_sec_params_t));

// Security parameters to be used for all security procedures.
sec_param.bond = SEC_PARAM_BOND;
sec_param.mitm = SEC_PARAM_MITM;
sec_param.lesc = SEC_PARAM_LESC;
sec_param.keypress = SEC_PARAM_KEYPRESS;
sec_param.io_caps = SEC_PARAM_IO_CAPABILITIES;
sec_param.oob = SEC_PARAM_OOB;
sec_param.min_key_size = SEC_PARAM_MIN_KEY_SIZE;
sec_param.max_key_size = SEC_PARAM_MAX_KEY_SIZE;
sec_param.kdist_own.enc = 1;
sec_param.kdist_own.id = 1;
sec_param.kdist_peer.enc = 1;
sec_param.kdist_peer.id = 1;

err_code = pm_sec_params_set(&sec_param);
APP_ERROR_CHECK(err_code);

err_code = pm_register(pm_evt_handler);
APP_ERROR_CHECK(err_code);
}

/**@brief Clear bond information from persistent storage.
*/
static void delete_bonds(void)
{
ret_code_t err_code;

NRF_LOG_INFO("Erase bonds!");

err_code = pm_peers_delete();
APP_ERROR_CHECK(err_code);
}

/**@brief Function for handling events from the BSP module.
*
* @param[in] event Event generated when button is pressed.
*/
static void bsp_event_handler(bsp_event_t event)
{
ret_code_t err_code;

switch (event)
{
case BSP_EVENT_SLEEP:
sleep_mode_enter();
break; // BSP_EVENT_SLEEP

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; // BSP_EVENT_DISCONNECT

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; // BSP_EVENT_KEY_0

default:
break;
}
}

/**@brief Function for initializing the Advertising functionality.
*/
static void advertising_init(void)
{
ret_code_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 = true;
init.advdata.flags = BLE_GAP_ADV_FLAGS_LE_ONLY_GENERAL_DISC_MODE;
init.advdata.uuids_complete.uuid_cnt = sizeof(m_adv_uuids) / sizeof(m_adv_uuids[0]);
init.advdata.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)
{
ret_code_t err_code;
bsp_event_t startup_event;

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)
{
if (NRF_LOG_PROCESS() == false)
{
nrf_pwr_mgmt_run();
}
}

/**@brief Function for starting advertising.
*/
static void advertising_start(bool erase_bonds)
{
if (erase_bonds == true)
{
delete_bonds();
// Advertising is started by PM_EVT_PEERS_DELETED_SUCEEDED event
}
else
{
ret_code_t err_code = ble_advertising_start(&m_advertising, BLE_ADV_MODE_FAST);

APP_ERROR_CHECK(err_code);
}
}

/**@brief Function for application main entry.
*/
int main(void)
{
bool erase_bonds;

// Initialize.
log_init();
timers_init();
buttons_leds_init(&erase_bonds);
power_management_init();
ble_stack_init();
gap_params_init();
gatt_init();
advertising_init();
services_init();
conn_params_init();
peer_manager_init();

// Start execution.
NRF_LOG_INFO("Template example started.");
application_timers_start();

data_len_set(251);

ble_opt_t opt;
memset(&opt, 0x00, sizeof(opt));
opt.common_opt.conn_evt_ext.enable = 1;
sd_ble_opt_set(BLE_COMMON_OPT_CONN_EVT_EXT, &opt);

advertising_start(erase_bonds);

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

/**
* @}
*/

[willdavies]

I've resolved this problem. No help needed.

[David Meiklejohn]

If you don't mind explaining - what was the problem? I'm also trying to optimise throughput, dumping data from my nRF52 device to a phone, so all clues on what works is helpful!