System on and keep RTC running in ultra-low power

[Ben]

Hi Sir/Miss,

I'm using nrf52832, softdevice s132 and SDK 17.0.2.

In specification, I saw nrf52832 has a ultra low power mode. 

It's in system on with full retention RAM or without retention RAM. 

I enable a RTC2 to tick and count the calendar, I want to let nrf52832 in ultra low power mode and running RTC.

Then, it can be wake up by using GPIOs.

Is it possible to run RTC in ultra low power mode?

Another question, I remove peripheral circuit in our board. It's just keeping components which nrf52832 needs.

I try it with sd_power_system_off(); The sleep current nears specification value (1uA).

But, when I use sd_app_evt_wait() or __WFE. That current is 2.X mA.

And, it can't be waked up in sd_app_evt_wait() and __WFE.

Here is my entering sleep mode code.

void shutdown_configuration(void)
{
  uint32_t err_code;
    
  nrf_gpio_cfg_input(BTN_START_PIN, NRF_GPIO_PIN_NOPULL);
  
  while(1)
  {
    if(nrf_gpio_pin_read(BTN_START_PIN) == 1)
    {
      nrf_gpio_pin_sense_t sense =  NRF_GPIO_PIN_SENSE_LOW;
      nrf_gpio_cfg_sense_set(BTN_START_PIN, sense);
      
      break;
    }
  }
  
  
  //err_code = sd_power_system_off();   // 1uA
  //err_code = sd_app_evt_wait();       // mA
  //APP_ERROR_CHECK(err_code);
  
  // mA
  __SEV();
  __WFE();
  __WFE();
}

Please help.

Thank you.

[Jørgen Holmefjord]

Hi,

It is possible to run the RTC in System ON mode, but not in System OFF. The expected current consumption is given by I_{ON_RAMOFF_RTC} in Current consumption: Ultra-low power, but note that any additional running peripheral will increase the current consumption, as entering System ON mode will not automatically power down peripherals.

If you are measuring 2.x mA current, some additional peripherals must be running. The usual suspects at this current-level is for instance UARTE in receive mode, or the SAADC peripheral.

Best regards,
Jørgen

[Ben]

Hi Jørgen,

I try to disable peripheral function. Power saving is under 1mA. But, it's still too high. I try to separate some code to check sleep current. Therefore, I still have few questions.

1. I comment BLE initial function code as below:

Before this, I don't run timer2_init() function (means comment timer2_init()), sleep current can be near 1uA. When I remove comment on timer2_init() (means run timer2_init()), and I disable and run un-initial timer2 before sleep. It's measured about 45uA. How do I close it?

//uart_init();
  log_init();

  timers_init();

  drv_gpio_configuration();
  
  pwm_init();
  
  saadc_sampling_event_init();
  saadc_init();
  timer2_init();      // Question 1
  
  /* Question 3
  sync_rtc(22, 6, 8, 20, 02, 55);
  lfclk_config();
  rtc_config();*/
  
  power_management_init();
  /* Question 4 comment for checking peripheral sleep current
  ble_stack_init();
  gap_params_init();
  gatt_init();
  services_init();
  advertising_init();
  conn_params_init();*/

2. Base on above code, I can't wake up SoC after entering system on mode. In previous wake up code, it works in system off. Instead of sd_power_system_off() to using WFE and WFI, it is ARM low-power standby mode.  It should be triggered by events for waking up. But, it looks like not working in my GPIO wake up pin.

3. Enable comments at Question 3 block (RTC) and comment timer2_init() in above code.  The current measured 11uA. It is not near 1.9 uA. 

4. Reserve RTC function (Question 3) and enable Question 4, and I don't enable advertising in this part. It has 820uA. Which function should be disabled?

Please assistance me to solve it.

Thank you.

[Jørgen Holmefjord]

Ben said:

Before this, I don't run timer2_init() function (means comment timer2_init()), sleep current can be near 1uA. When I remove comment on timer2_init() (means run timer2_init()), and I disable and run un-initial timer2 before sleep. It's measured about 45uA. How do I close it?

I do not know what is inside your timer2_init function. Is this using the TIMER peripheral, or is it an RTC timer? 

Ben said:

2. Base on above code, I can't wake up SoC after entering system on mode. In previous wake up code, it works in system off. Instead of sd_power_system_off() to using WFE and WFI, it is ARM low-power standby mode.  It should be triggered by events for waking up. But, it looks like not working in my GPIO wake up pin.

How did you configure the pin for wakeup? Enabling sense on the pin may not generate any events unless GPIOTE PORT event is also cleared. You may have a look at this example.

Ben said:

3. Enable comments at Question 3 block (RTC) and comment timer2_init() in above code.  The current measured 11uA. It is not near 1.9 uA. 

Other parts of the application, like logger, PWM, etc may also contribute to the current. If you should get lowest current, you need to disable all peripherals in your application.

Ben said:

4. Reserve RTC function (Question 3) and enable Question 4, and I don't enable advertising in this part. It has 820uA. Which function should be disabled?

If you start the softdevice and advertising, the current will depend on the advertising interval and/or connection interval if any connections are established. What are you using to measure the current consumption? If your equipment does not have high enough sample rate, the current may not be correctly measured. If you do not have it already, I would highly recommend you to get a PPK 2 for current measurements.

[Ben]

Jørgen Holmefjord said:

I do not know what is inside your timer2_init function. Is this using the TIMER peripheral, or is it an RTC timer? 

Yes, timer2_init is using TIMER 2 peripheral. The code of timer2_init is as below:

void timer2_init(void)
{
  ret_code_t err_code;
  
  nrf_drv_timer_config_t timer2_cfg;
  timer2_cfg.bit_width = NRF_TIMER_BIT_WIDTH_16;
  timer2_cfg.frequency = NRF_TIMER_FREQ_31250Hz;
  timer2_cfg.interrupt_priority = APP_IRQ_PRIORITY_LOW; // Do not set high, that will impact setting up sleep mode
  timer2_cfg.mode = NRF_TIMER_MODE_TIMER;
  
  err_code = nrf_drv_timer_init(&m_timer2, &timer2_cfg, timer2_handler);
  APP_ERROR_CHECK(err_code);
  
  nrf_drv_timer_extended_compare(
         &m_timer2, NRF_TIMER_CC_CHANNEL0, nrf_drv_timer_ms_to_ticks(&m_timer2 ,TIMER2_TICKS), 
         NRF_TIMER_SHORT_COMPARE0_CLEAR_MASK, true);
  
  nrf_drv_timer_enable(&m_timer2);
}

In current code, I disable timer 2 and change function to app_timer_create (like ble_app_hrs example) in our agent FAE's suggestion.

Jørgen Holmefjord said:

How did you configure the pin for wakeup? Enabling sense on the pin may not generate any events unless GPIOTE PORT event is also cleared. You may have a look at this example.

I change wakeup method with your tips and use sd_power_mode_set(NRF_POWER_MODE_LOWPWR).

It still has some problem with RTC. When I remove RTC function, it can wake up quickly.

Fullscreen drv_calendar.c Download

#include "nrf_drv_rtc.h"
#include "nrf_drv_clock.h"
#include "nrf_gpio.h"
#include "drv_calendar.h"

typedef struct{
  uint8_t msec_tick_cnt;
  uint8_t sec_tick_cnt;
  uint8_t min_tick_cnt;
  uint8_t hour_tick_cnt;
  uint8_t day_tick_cnt;
  uint8_t month_tick_cnt;
  uint8_t year_tick_cnt;
}rtc_timer_t;

#define COMPARE_COUNTERTIME  (3UL)                  //< Get Compare event COMPARE_TIME seconds after the counter starts from 0.

const nrf_drv_rtc_t rtc2 = NRF_DRV_RTC_INSTANCE(2); /**< Declaring an instance of nrf_drv_rtc for RTC2. */

rtc_timer_t rtc_timer;

uint8_t day_of_month[12] = {31, 28, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31};
//uint8_t leap_year[] = {24, 28, 32, 36, 40, 44, 48, 52, 56, 60, 64, 68, 72, 76, 80};

void sync_rtc(uint8_t yrs, uint8_t mon, uint8_t days, uint8_t hrs, uint8_t mins, uint8_t secs)
{
  rtc_timer.year_tick_cnt       = yrs;
  rtc_timer.month_tick_cnt      = mon;
  rtc_timer.day_tick_cnt        = days;
  rtc_timer.hour_tick_cnt       = hrs;
  rtc_timer.min_tick_cnt        = mins;
  rtc_timer.sec_tick_cnt        = secs;
}

#pragma optimize=none
static void rtc_handler(nrf_drv_rtc_int_type_t int_type)
{
  switch(int_type)
  {
    //case NRF_DRV_RTC_INT_COMPARE0:
    //  break;
    case NRF_DRV_RTC_INT_TICK:
      rtc_timer.msec_tick_cnt++;
      
      if(rtc_timer.msec_tick_cnt >= 8)
      {
        rtc_timer.msec_tick_cnt = 0;
        rtc_timer.sec_tick_cnt++;
        //nrf_gpio_pin_toggle(14);
        if(rtc_timer.sec_tick_cnt >= 60)
        {
          rtc_timer.sec_tick_cnt = 0;
          rtc_timer.min_tick_cnt++;
          
          if(rtc_timer.min_tick_cnt >= 60)
          {
            rtc_timer.min_tick_cnt = 0;
            rtc_timer.hour_tick_cnt++;
            
            if(rtc_timer.hour_tick_cnt >= 24)
            {
              rtc_timer.hour_tick_cnt = 0;
              rtc_timer.day_tick_cnt++;
              
              if(rtc_timer.year_tick_cnt%4 == 0 && rtc_timer.month_tick_cnt == 2)
                day_of_month[1] = 29;
              else
                day_of_month[1] = 28;
                  
              if(rtc_timer.day_tick_cnt > day_of_month[rtc_timer.month_tick_cnt - 1])
              {
                if(rtc_timer.month_tick_cnt == 12)
                {
                  rtc_timer.month_tick_cnt = 0;
                  rtc_timer.year_tick_cnt++;
                }
                rtc_timer.day_tick_cnt = 1;
                rtc_timer.month_tick_cnt++;
              }
            }
          }
        }
      }
      break;
  }
}
#pragma optimize=high
void lfclk_config(void)
{
    ret_code_t err_code = nrf_drv_clock_init();
    APP_ERROR_CHECK(err_code);

    nrf_drv_clock_lfclk_request(NULL);
}

void rtc_config(void)
{
  uint32_t err_code;
  
  //Initialize RTC instance
  nrf_drv_rtc_config_t config = NRF_DRV_RTC_DEFAULT_CONFIG;
  config.prescaler = 4095;
  err_code = nrf_drv_rtc_init(&rtc2, &config, rtc_handler);
  APP_ERROR_CHECK(err_code);
  
  //Enable tick event & interrupt
  nrf_drv_rtc_tick_enable(&rtc2,true);
  
  //Set compare channel to trigger interrupt after COMPARE_COUNTERTIME seconds
  //err_code = nrf_drv_rtc_cc_set(&rtc2,0,COMPARE_COUNTERTIME * 8,true);
  //APP_ERROR_CHECK(err_code);
  
  //Power on RTC instance
  nrf_drv_rtc_enable(&rtc2);
}

Fullscreen 08685.main.c Download

/**
 * Copyright (c) 2014 - 2021, Nordic Semiconductor ASA
 *
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without modification,
 * are permitted provided that the following conditions are met:
 *
 * 1. Redistributions of source code must retain the above copyright notice, this
 *    list of conditions and the following disclaimer.
 *
 * 2. Redistributions in binary form, except as embedded into a Nordic
 *    Semiconductor ASA integrated circuit in a product or a software update for
 *    such product, must reproduce the above copyright notice, this list of
 *    conditions and the following disclaimer in the documentation and/or other
 *    materials provided with the distribution.
 *
 * 3. Neither the name of Nordic Semiconductor ASA nor the names of its
 *    contributors may be used to endorse or promote products derived from this
 *    software without specific prior written permission.
 *
 * 4. This software, with or without modification, must only be used with a
 *    Nordic Semiconductor ASA integrated circuit.
 *
 * 5. Any software provided in binary form under this license must not be reverse
 *    engineered, decompiled, modified and/or disassembled.
 *
 * THIS SOFTWARE IS PROVIDED BY NORDIC SEMICONDUCTOR ASA "AS IS" AND ANY EXPRESS
 * OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
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 * DISCLAIMED. IN NO EVENT SHALL NORDIC SEMICONDUCTOR ASA OR CONTRIBUTORS BE
 * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
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 * GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
 * OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 *
 */
/** @file
 *
 * @defgroup ble_sdk_uart_over_ble_main main.c
 * @{
 * @ingroup  ble_sdk_app_nus_eval
 * @brief    UART over BLE application main file.
 *
 * This file contains the source code for a sample application that uses the Nordic UART service.
 * This application uses the @ref srvlib_conn_params module.
 */

/*
Date            Version         Description
Apr 15, 2022    001             1. Add WDT 
                                2. Remove advertising after disconnection
                                3. Add disconnection with click BLE button
                                4. Change BLE_GATT_ATT_MTU_DEFAULT is from 23 to 9
Jun 02, 2022                    5. Change button interrupt to polling
*/   
/*
For saadc               sdk_config.h    PPI_ENABLED
                                        TIMER3_ENABLED
//For button timer        sdk_config.h    TIMER2_ENABLED -> DISABLE
For RTC                 sdk_config.h    RTC2_ENABLED, NRFX_RTC_ENABLED, RTC_ENABLED
*/

#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"

#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"

// user add libraries
#include "main.h"
#include "user_boards.h"
#include "user_application.h"
#include "user_parameters.h"
#include "drv_gpio.h"
#include "drv_timer.h"
#include "drv_pwm.h"
#include "drv_saadc.h"
#include "drv_pwr_mgmt.h"
#include "drv_calendar.h"
#include "nrf_gpio.h"
   
#define APP_BLE_CONN_CFG_TAG            1                                           /**< A tag identifying the SoftDevice BLE configuration. */

#define DEVICE_NAME                     "Smart_Nebulizer"                               /**< 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. */



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_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}
};

extern dev_status_t dev_status;
extern app_ui_t app_ui;
extern app_user_status_t app_user_status;
extern io_status_t io_status;
extern uint8_t PWM_FREQ;

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

uint8_t wakeup_test = 0;

/**@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 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 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.
 */
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:
            dev_status.ble_conn = true;
            
            NRF_LOG_INFO("Connected");
            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:
            dev_status.ble_conn = false;
            app_ui.ble_blink_cnt = 0;
            
            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);
}

//#ifdef ORIGIN_EXAMPLE 
///**@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);
//}
//#endif

/**@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.
 */
void advertising_start(void)
{
    uint32_t err_code = ble_advertising_start(&m_advertising, BLE_ADV_MODE_FAST);
    APP_ERROR_CHECK(err_code);
}

/*void ble_advertising_stop(void)
{
    ret_code_t = err_code;
    (void) sd_ble_gap_adv_stop(m_advertising.adv_handle);
}*/

ret_code_t ble_advertising_stop(void)
{
    return sd_ble_gap_adv_stop(m_advertising.adv_handle);
}

void transfer_data_via_nus(uint8_t *data, uint16_t len)
{
    ret_code_t err_code;
  
    do
    {
        uint16_t length = len;
        err_code = ble_nus_data_send(&m_nus, data, &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);
}

/*void GPIOTE_IRQHandler(void)
{
    // This handler will be run after wakeup from system ON (GPIO wakeup)
    if(NRF_GPIOTE->EVENTS_PORT)
    {
        NRF_GPIOTE->EVENTS_PORT = 0;
        
        //nrf_gpio_pin_clear(LED_1);
    }
}*/

/**@brief Application main function.
 */
int main(void)
{
  // Initialize.

  //uart_init();
  log_init();

  timers_init();

  drv_gpio_configuration();
  
  PWM_FREQ = PIEZO_TOP_VALUE;
  pwm_init();
  
  saadc_sampling_event_init();
  saadc_init();
  create_button_timers();
  button_timer_start();
  //timer2_init();      // for checking button gpio
  sync_rtc(22, 6, 8, 20, 02, 55);
  lfclk_config();
  rtc_config();
  
  
  power_management_init();
  ble_stack_init();
  gap_params_init();
  gatt_init();
  services_init();
  advertising_init();
  conn_params_init();
  
  // Enter main loop.
  for (;;)
  {
    idle_state_handle();    
  }
}


/**
 * @}
 */

Yellow (Channel 1) is button pin. Press one times (Low) to enter some process, and press again to enter idle mode.

In first wake up, it should be pressed twice. But in second wake up, it should pressed few times to wake up. Please see below video.

 

Jørgen Holmefjord said:

Other parts of the application, like logger, PWM, etc may also contribute to the current. If you should get lowest current, you need to disable all peripherals in your application.

In current code, it costs near 3uA. It looks like to spend some time reaching 3uA.

Jørgen Holmefjord said:

If you start the softdevice and advertising, the current will depend on the advertising interval and/or connection interval if any connections are established. What are you using to measure the current consumption? If your equipment does not have high enough sample rate, the current may not be correctly measured. If you do not have it already, I would highly recommend you to get a PPK 2 for current measurements.

I've ordered the PPK2 in one month ago. But, the lead time is too long which needs 3 month. In current, I'm using  keysight 34470A to measure it. The sample rate is 50kHz. If it's not enough, I should find another one before PPK2 arrival.

Thank you.

[Jørgen Holmefjord]

Ben said:

In current code, I disable timer 2 and change function to app_timer_create (like ble_app_hrs example) in our agent FAE's suggestion.

Good, TIMER will have high current consumption. RTC/app_timer is low power.

Ben said:

In current code, it costs near 3uA. It looks like to spend some time reaching 3uA.

Yes, 3uA should be good, but I see in your video that it takes some time to reach this current. Could there be some averaging configuration of the Keysight unit that makes it take this long? I do not have any experience with this instrument myself. You should check the manual.

Ben said:

I've ordered the PPK2 in one month ago. But, the lead time is too long which needs 3 month. In current, I'm using  keysight 34470A to measure it. The sample rate is 50kHz. If it's not enough, I should find another one before PPK2 arrival.

That is unfortunate. I believe 50 kHz should be enough, the PPK2 have maximum 100kHz sampling. Please check the manual of your instrument to make sure it is not configured in some averaging mode.