nRF52840 output the 32.768kHz clock on any GPIO in SPI Communication.

[rohit]

Dear Nordic Developer Zone,

I am working on MAX30003 ECG (https://datasheets.maximintegrated.com/en/ds/MAX30003.pdf)  with Nrf52840-DK. My sensor is work on the 32.768kHz external clock. 

but in Nrf I don't know which GPIO_PIN is assigned for that.

I visited below link but I unable to find solutions: 

https://devzone.nordicsemi.com/f/nordic-q-a/23474/nrf52832-fclk-pin/92210#92210

https://devzone.nordicsemi.com/f/nordic-q-a/15996/can-the-nrf52-output-the-32-768khz-clock-on-a-gpio

I am referring (SDK15.2 -PCA10056-spi code)

I have some questions about that:

1) Can I do the merging of timer and gpiote example code into SPI?

2) please give me detail about how to generate 32.768kHz clock ?

I have stuck  on below issue, 

https://maximsupport.microsoftcrmportals.com/en-us/knowledgebase/article/000096610

Thanks,

Rohit Patil

[haakonsh]

1) Yes of course.

2) You can't output the 32.768 clock on a GPIO. What you can do is share an external 32.768kHz clock with both the MAX30003 and the nRF52840 by setting the BYPASS and EXTERNAL bits in the LFCLKSRC register. 

[rohit]

Hi,

Thanks for the suggestion,

I am stuck in max30003 and nrf52840 because of I unable to read ECG_FIFO register value. it's showing zero.

(I try to  read INFO Register and other read register then  I got  default result as per max30003 datasheet ,surely my driver is working properly)

I discussed this issue  on MAXIM Forum.

maximsupport.microsoftcrmportals.com/.../000096610

As per his suggestion,  if I  check crystal oscillator of max30003 working or not ?, But it's working.

I got 32.768khz frequency on fclk pin of max30003.

Let me know,

1) is it any configuration required from nrf52840 side?

I am generating 16khz frequency on gpio pin using RTC example,

2) is it possible to generate 32.768khz using RTC? How to generate?

Kindly help me,

Thanks,

Rohit

[haakonsh]

Answer in the other post you made.

[rohit]

@haakonsh

I got 32KHZ frequency on GPIO pin using GPIOTE example. But if I merge this code into my Ble_app_uart I am not getting the frequency. 

I refer to this link 

https://devzone.nordicsemi.com/f/nordic-q-a/26207/gpio-interrupt-not-work-in-ble_app_uart/103217#103217

but I am not getting a clear solution, 

[haakonsh]

" But if I merge this code into my Ble_app_uart I am not getting the frequency. "

I need more information on this issue.

[rohit]

haakonsh said:

I need more information on this issue.

OK;

I am working on one sensor which is required 32KHz clock frequency. so I generated 32KHz frequency on one of NRF GPIO Pin using GPIOTE example. 

But I have to merge this code into Ble_app_uart, because of my plan to take sensor data using Bluetooth, so if I merge GPIOTE code (Which is already generated 32.0KHz Frequency) into BLE_APP_UART (SDK15.2.0- PCA10056-S140).

 But when I merge it with my working ble_app_uart code then GPIOTE stop working. it can't show 32.0KHz frequency, so please help me with these issues.

please check my below code.

Ble_App_Uart + GPIOTE

/*Working ECG And RR Interval Code with Bluetooth and Pushing data on Server and Generating Interrupt (Timer) */

#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 "nrfx_spi.h"
#include "nrf_drv_spi.h"

#include "nrfx_spim.h"
#include "nrf_delay.h"
#include "boards.h"
#include "app_error.h"
#include <string.h>
#include "nrf_log.h"
#include "nrf_log_ctrl.h"
#include "nrf_log_default_backends.h"
#include "stdio.h"
//#include "app_uart.h"
//#include "nrf_uart.h"
#include <nrfx_ppi.h>


#include <stdbool.h>
#include <stdint.h>
#include "nrf.h"
#include "nrf_drv_timer.h"
#include "bsp.h"
#include "app_error.h"



#include "nrf_gpiote.h"
#include "nrf_gpio.h"
#include "boards.h"
#include "nrf_drv_ppi.h"
#include "nrf_drv_gpiote.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"




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

#define DEVICE_NAME                     "ECG_BLE_Timer_RR"                               /**< 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                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 UART_TX_BUF_SIZE                256                                         /**< UART TX buffer size. */
#define UART_RX_BUF_SIZE                256                                         /**< UART RX buffer size. */

/**/
#define SPI_SCK_PIN 3
#define SPI_MISO_PIN 28
#define SPI_MOSI_PIN 4
#define SPI_SS_PIN 29

#define   STATUS          0x01
#define   EN_INT          0x02
#define   EN_INT2         0x03
#define   MNGR_INT        0x04
#define   MNGR_DYN        0x05
#define   SW_RST          0x08
#define   SYNCH           0x09
#define   FIFO_RST        0x0A
#define   INFO            0x0F
#define   CNFG_GEN        0x10
#define   CNFG_CAL        0x12
#define   CNFG_EMUX       0x14
#define   CNFG_ECG        0x15
#define   CNFG_RTOR1      0x1D
#define   CNFG_RTOR2      0x1E
#define   ECG_FIFO_BURST  0x20
#define   ECG_FIFO        0x21
#define   RTOR            0x25
#define   NO_OP           0x7F
#define SPI_INSTANCE  0 /**< SPI instance index. */
 const nrf_drv_spi_t spi = NRF_DRV_SPI_INSTANCE(SPI_INSTANCE);  /**< SPI instance. */
 volatile bool spi_xfer_done;  /**< Flag used to indicate that SPI instance completed the transfer. */
 uint8_t       m_tx_buf[4] = {0x00, 0x00, 0x00, 0x00};           /**< TX buffer. */
 uint8_t       m_rx_buf[4];    /**< RX buffer. */
static const uint8_t m_length = sizeof(m_tx_buf);        /**< Transfer length. */
 uint32_t datareturn1 = 0x00;
 uint32_t datareturn2 = 0x00;
 uint32_t RR_Interval = 0x00;
 uint32_t HR_Read = 0x00;
 
 const nrf_drv_timer_t TIMER_LED = NRF_DRV_TIMER_INSTANCE(2);
 uint32_t i=0;
 
    uint32_t err_code;
	  uint8_t ARRAY[10];
    uint16_t size = 9;
 
    uint32_t err_code1;
    uint8_t ARRAY1[3];
    uint16_t size1 = 2;
 
    uint32_t HR;
    uint8_t ARRAY2[3];
    uint16_t size2 = 3;
	
#ifdef ARDUINO_1_PIN
    #define GPIO_OUTPUT_PIN_NUMBER ARDUINO_1_PIN  /**< Pin number for output. */
#endif
#ifndef GPIO_OUTPUT_PIN_NUMBER
    #error "Please indicate output pin"
#endif

static nrf_drv_timer_t timer = NRF_DRV_TIMER_INSTANCE(0);

void timer_dummy_handler(nrf_timer_event_t event_type, void * p_context){}

	

 void spi_event_handler(nrf_drv_spi_evt_t const * p_event,
                       void *                    p_context)
{
    spi_xfer_done = true;
//    NRF_LOG_INFO("Transfer completed.");
    if (m_rx_buf[0] != 0)
    {
//        NRF_LOG_INFO(" Received:");
        NRF_LOG_HEXDUMP_INFO(m_rx_buf, strlen((const char *)m_rx_buf));
    }
}
/**/
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);
}



 void led_blinking_setup()
{
    uint32_t compare_evt_addr;
    uint32_t gpiote_task_addr;
    nrf_ppi_channel_t ppi_channel;
    ret_code_t err_code;
    nrf_drv_gpiote_out_config_t config = GPIOTE_CONFIG_OUT_TASK_TOGGLE(false);

    err_code = nrf_drv_gpiote_out_init(GPIO_OUTPUT_PIN_NUMBER, &config);
    APP_ERROR_CHECK(err_code);


    nrf_drv_timer_extended_compare(&timer, (nrf_timer_cc_channel_t)0, 251, NRF_TIMER_SHORT_COMPARE0_CLEAR_MASK, false);

    err_code = nrf_drv_ppi_channel_alloc(&ppi_channel);
    APP_ERROR_CHECK(err_code);

    compare_evt_addr = nrf_drv_timer_event_address_get(&timer, NRF_TIMER_EVENT_COMPARE0);
    gpiote_task_addr = nrf_drv_gpiote_out_task_addr_get(GPIO_OUTPUT_PIN_NUMBER);

    err_code = nrf_drv_ppi_channel_assign(ppi_channel, compare_evt_addr, gpiote_task_addr);
    APP_ERROR_CHECK(err_code);

    err_code = nrf_drv_ppi_channel_enable(ppi_channel);
    APP_ERROR_CHECK(err_code);

    nrf_drv_gpiote_out_task_enable(GPIO_OUTPUT_PIN_NUMBER);
}
void Frequency_init()
{
	 ret_code_t err_code;

    err_code = nrf_drv_ppi_init();
    APP_ERROR_CHECK(err_code);

//    err_code = nrf_drv_gpiote_init();
//    APP_ERROR_CHECK(err_code);

    nrf_drv_timer_config_t timer_cfg = NRF_DRV_TIMER_DEFAULT_CONFIG;
    err_code = nrf_drv_timer_init(&timer, &timer_cfg, timer_dummy_handler);
    APP_ERROR_CHECK(err_code);
#ifdef NRF51
    //Workaround for PAN-73.
    *(uint32_t *)0x40008C0C = 1;
#endif

    // Setup PPI channel with event from TIMER compare and task GPIOTE pin toggle.
    led_blinking_setup();

    // Enable timer
    nrf_drv_timer_enable(&timer);

}
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 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 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;
 uint32_t led_to_invert = 1; //((i++) % LED_1);
    switch (p_ble_evt->header.evt_id)
    {
        case BLE_GAP_EVT_CONNECTED:
//					   bsp_board_led_invert(led_to_invert);
            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);
            break;

        case BLE_GAP_EVT_DISCONNECTED:
//            NRF_LOG_INFO("Disconnected");
            // LED indication will be changed when advertising starts.
            m_conn_handle = BLE_CONN_HANDLE_INVALID;
            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.
            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.
            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 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 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_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);
}


/**@brief Application main function.
 */




 

int main(void)
{
    bool erase_bonds;
    uart_init();
    log_init();
	  timers_init();
//  buttons_leds_init(&erase_bonds);
    power_management_init();
    ble_stack_init();
    gap_params_init();
    gatt_init();
    services_init();
    advertising_init();
    conn_params_init();
    advertising_start();
	  
    nrf_drv_spi_config_t spi_config = NRF_DRV_SPI_DEFAULT_CONFIG;
    spi_config.ss_pin   = SPI_SS_PIN;       
    spi_config.miso_pin = SPI_MISO_PIN;
    spi_config.mosi_pin = SPI_MOSI_PIN;
    spi_config.sck_pin  = SPI_SCK_PIN;
    spi_config.frequency = NRF_SPI_FREQ_125K;
    spi_config.mode = NRF_SPI_MODE_0;
    APP_ERROR_CHECK(nrf_drv_spi_init(&spi, &spi_config, spi_event_handler, NULL));
    Frequency_init();
    for (;;)
    {
						
	      idle_state_handle();
    }
}

GPIOTE- 32.0KHz

#include <stdbool.h>
#include <stdint.h>
#include "nrf.h"
#include "nrf_gpiote.h"
#include "nrf_gpio.h"
#include "boards.h"
#include "nrf_drv_ppi.h"
#include "nrf_drv_timer.h"
#include "nrf_drv_gpiote.h"
#include "app_error.h"

#ifdef BSP_LED_0
    #define GPIO_OUTPUT_PIN_NUMBER BSP_LED_0  /**< Pin number for output. */
#endif
#ifndef GPIO_OUTPUT_PIN_NUMBER
    #error "Please indicate output pin"
#endif

static nrf_drv_timer_t timer = NRF_DRV_TIMER_INSTANCE(0);

void timer_dummy_handler(nrf_timer_event_t event_type, void * p_context){}

static void led_blinking_setup()
{
    uint32_t compare_evt_addr;
    uint32_t gpiote_task_addr;
    nrf_ppi_channel_t ppi_channel;
    ret_code_t err_code;
    nrf_drv_gpiote_out_config_t config = GPIOTE_CONFIG_OUT_TASK_TOGGLE(false);

    err_code = nrf_drv_gpiote_out_init(GPIO_OUTPUT_PIN_NUMBER, &config);
    APP_ERROR_CHECK(err_code);


    nrf_drv_timer_extended_compare(&timer, (nrf_timer_cc_channel_t)0, 251, NRF_TIMER_SHORT_COMPARE0_CLEAR_MASK, false);

    err_code = nrf_drv_ppi_channel_alloc(&ppi_channel);
    APP_ERROR_CHECK(err_code);

    compare_evt_addr = nrf_drv_timer_event_address_get(&timer, NRF_TIMER_EVENT_COMPARE0);
    gpiote_task_addr = nrf_drv_gpiote_out_task_addr_get(GPIO_OUTPUT_PIN_NUMBER);

    err_code = nrf_drv_ppi_channel_assign(ppi_channel, compare_evt_addr, gpiote_task_addr);
    APP_ERROR_CHECK(err_code);

    err_code = nrf_drv_ppi_channel_enable(ppi_channel);
    APP_ERROR_CHECK(err_code);

    nrf_drv_gpiote_out_task_enable(GPIO_OUTPUT_PIN_NUMBER);
}

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

    err_code = nrf_drv_ppi_init();
    APP_ERROR_CHECK(err_code);

    err_code = nrf_drv_gpiote_init();
    APP_ERROR_CHECK(err_code);

    nrf_drv_timer_config_t timer_cfg = NRF_DRV_TIMER_DEFAULT_CONFIG;
    err_code = nrf_drv_timer_init(&timer, &timer_cfg, timer_dummy_handler);
    APP_ERROR_CHECK(err_code);
#ifdef NRF51
    //Workaround for PAN-73.
    *(uint32_t *)0x40008C0C = 1;
#endif

    // Setup PPI channel with event from TIMER compare and task GPIOTE pin toggle.
    led_blinking_setup();

    // Enable timer
    nrf_drv_timer_enable(&timer);

    while (true)
    {
        // Do Nothing - GPIO can be toggled without software intervention.
    }
}

[haakonsh]

static nrf_drv_timer_t timer = NRF_DRV_TIMER_INSTANCE(0); 

TIMER0 is used by the SoftDevice, you need to use TIMER1 or above.

See System On Chip Requirements: Hardware peripherals, from S132 spec.