High Power Consumption on Custom nRF52811 Board (~4mA vs 17µA on DK)

[Purvesh patel]

Hardware Setup

Custom Board:

• nRF52811 chip
• No external LFXO (32.768 kHz crystal)
• No LC filter for DC-DC regulator
• No peripherals connected (no LEDs, buttons, sensors, etc.)
• Minimal design - just the nRF chip with basic power supply

Development Kit (for testing):

• nRF52840 DK (PCA10056)
• Standard configuration with all components

Problem Description

I'm experiencing significantly higher power consumption on my custom nRF52811 board compared to the nRF52840 DK running identical firmware.

Current Consumption:

• nRF52840 DK: ~17 µA average (expected low-power behavior)
• Custom nRF52811 Board: ~3.66-4 mA average (215x higher!)

See attached Power Profiler screenshots showing the same firmware running on both boards.

Firmware Configuration

• Logging: DISABLED
• DC-DC: Disabled (no LC filter or LFXO on custom board)
• LFCLK Source: Configured to use internal RC oscillator (no external LFXO)
• All unused GPIOs: Configured as inputs with pulldown
• No peripherals enabled (UART, SPI, I2C all disabled)
• BLE: Standard connection parameters

The firmware runs perfectly on the nRF52840 DK with excellent power consumption, but shows this massive difference on the custom nRF52811 board.

Note: Testing was done using nRF52840 DK as a reference since I don't have an nRF52811 DK available. The firmware is compiled for nRF52811 and runs correctly on the custom board.

Expected vs Actual

Expected current without DC-DC regulator:

•  Power consumption on dk

• 
• 

Actual current on custom board:

• Baseline: ~3.66-4 mA continuous
• Periodic spikes: ~15-16 mA (BLE activity)
• 
• 

Questions

1. Why is there such a massive difference (17µA vs 4mA) with identical firmware?

2. What hardware factors could cause this 215x power consumption difference?

   • PCB layout issues?
   • Missing/incorrect decoupling capacitors?
   • Pin configuration requirements I'm missing?
   • Reset pin handling?

3. Are there specific hardware design requirements for low power operation beyond DC-DC and LFXO?

   • Required pull-up/pull-down resistors?
   • Specific voltage regulator characteristics?
   • Critical PCB layout considerations?

4. How can I debug this systematically?

   • What intermediate measurements should I take?
   • Any specific register configurations to check?
   • Tools or techniques to isolate the issue?

Additional Information

• No external flash, sensors, or other ICs on the board
  
  

edit:- with this commented out code from ble blinky

int main(void)
{
    // Initialize.
    /*
    log_init();
    leds_init();
    timers_init();
    buttons_init();
    ble_stack_init();
    gap_params_init();
    gatt_init();
    services_init();
    advertising_init();
    conn_params_init();

    // Start execution.
    NRF_LOG_INFO("Blinky example started.");
    advertising_start();
*/
     power_management_init();
    // Enter main loop.
    for (;;)
    {
        idle_state_handle();
    }
}

similar results with this

/**
 * Copyright (c) 2015 - 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
 * OF MERCHANTABILITY, NONINFRINGEMENT, AND FITNESS FOR A PARTICULAR PURPOSE ARE
 * DISCLAIMED. IN NO EVENT SHALL NORDIC SEMICONDUCTOR ASA OR CONTRIBUTORS BE
 * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE
 * 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.
 *
 */
/**
 * @brief Blinky Sample Application main file.
 *
 * This file contains the source code for a sample server application using the LED Button service.
 */

#include <stdint.h>
#include <string.h>
#include "nordic_common.h"
#include "nrf.h"
#include "app_error.h"
#include "ble.h"
#include "ble_err.h"
#include "ble_hci.h"
#include "ble_srv_common.h"
#include "ble_advdata.h"
#include "ble_conn_params.h"
#include "nrf_sdh.h"
#include "nrf_sdh_ble.h"
#include "boards.h"
#include "app_timer.h"
#include "app_button.h"
#include "ble_lbs.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"


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

#define DEVICE_NAME                     "Nordic_Blinky"                         /**< Name of device. Will be included in the advertising data. */

#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 APP_ADV_INTERVAL                64                                      /**< The advertising interval (in units of 0.625 ms; this value corresponds to 40 ms). */
#define APP_ADV_DURATION                BLE_GAP_ADV_TIMEOUT_GENERAL_UNLIMITED   /**< The advertising time-out (in units of seconds). When set to 0, we will never time out. */


#define MIN_CONN_INTERVAL               MSEC_TO_UNITS(100, UNIT_1_25_MS)        /**< Minimum acceptable connection interval (0.5 seconds). */
#define MAX_CONN_INTERVAL               MSEC_TO_UNITS(200, UNIT_1_25_MS)        /**< Maximum acceptable connection interval (1 second). */
#define SLAVE_LATENCY                   0                                       /**< Slave latency. */
#define CONN_SUP_TIMEOUT                MSEC_TO_UNITS(4000, UNIT_10_MS)         /**< Connection supervisory time-out (4 seconds). */

#define FIRST_CONN_PARAMS_UPDATE_DELAY  APP_TIMER_TICKS(20000)                  /**< Time from initiating event (connect or start of notification) to first time sd_ble_gap_conn_param_update is called (15 seconds). */
#define NEXT_CONN_PARAMS_UPDATE_DELAY   APP_TIMER_TICKS(5000)                   /**< Time between each call to sd_ble_gap_conn_param_update after the first call (5 seconds). */
#define MAX_CONN_PARAMS_UPDATE_COUNT    3                                       /**< Number of attempts before giving up the connection parameter negotiation. */

#define BUTTON_DETECTION_DELAY          APP_TIMER_TICKS(50)                     /**< Delay from a GPIOTE event until a button is reported as pushed (in number of timer ticks). */

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


BLE_LBS_DEF(m_lbs);                                                             /**< LED Button Service instance. */
NRF_BLE_GATT_DEF(m_gatt);                                                       /**< GATT module instance. */
NRF_BLE_QWR_DEF(m_qwr);                                                         /**< Context for the Queued Write module.*/

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

static uint8_t m_adv_handle = BLE_GAP_ADV_SET_HANDLE_NOT_SET;                   /**< Advertising handle used to identify an advertising set. */
static uint8_t m_enc_advdata[BLE_GAP_ADV_SET_DATA_SIZE_MAX];                    /**< Buffer for storing an encoded advertising set. */
static uint8_t m_enc_scan_response_data[BLE_GAP_ADV_SET_DATA_SIZE_MAX];         /**< Buffer for storing an encoded scan data. */

/**@brief Struct that contains pointers to the encoded advertising data. */
static ble_gap_adv_data_t m_adv_data =
{
    .adv_data =
    {
        .p_data = m_enc_advdata,
        .len    = BLE_GAP_ADV_SET_DATA_SIZE_MAX
    },
    .scan_rsp_data =
    {
        .p_data = m_enc_scan_response_data,
        .len    = BLE_GAP_ADV_SET_DATA_SIZE_MAX

    }
};

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


/**@brief Function for the Timer initialization.
 *
 * @details Initializes the timer module.
 */
static void timers_init(void)
{
    // Initialize timer module, making it use the scheduler
    ret_code_t err_code = app_timer_init();
    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);

    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 initializing the GATT module.
 */
static void gatt_init(void)
{
    ret_code_t err_code = nrf_ble_gatt_init(&m_gatt, NULL);
    APP_ERROR_CHECK(err_code);
}


/**@brief Function for initializing the Advertising functionality.
 *
 * @details Encodes the required advertising data and passes it to the stack.
 *          Also builds a structure to be passed to the stack when starting advertising.
 */
static void advertising_init(void)
{
    ret_code_t    err_code;
    ble_advdata_t advdata;
    ble_advdata_t srdata;
//    NRF_POWER->DCDCEN = 1;

    ble_uuid_t adv_uuids[] = {{LBS_UUID_SERVICE, m_lbs.uuid_type}};

    // Build and set advertising data.
    memset(&advdata, 0, sizeof(advdata));

    advdata.name_type          = BLE_ADVDATA_FULL_NAME;
    advdata.include_appearance = true;
    advdata.flags              = BLE_GAP_ADV_FLAGS_LE_ONLY_GENERAL_DISC_MODE;


    memset(&srdata, 0, sizeof(srdata));
    srdata.uuids_complete.uuid_cnt = sizeof(adv_uuids) / sizeof(adv_uuids[0]);
    srdata.uuids_complete.p_uuids  = adv_uuids;

    err_code = ble_advdata_encode(&advdata, m_adv_data.adv_data.p_data, &m_adv_data.adv_data.len);
    APP_ERROR_CHECK(err_code);

    err_code = ble_advdata_encode(&srdata, m_adv_data.scan_rsp_data.p_data, &m_adv_data.scan_rsp_data.len);
    APP_ERROR_CHECK(err_code);

    ble_gap_adv_params_t adv_params;

    // Set advertising parameters.
    memset(&adv_params, 0, sizeof(adv_params));

    adv_params.primary_phy     = BLE_GAP_PHY_1MBPS;
    adv_params.duration        = APP_ADV_DURATION;
    adv_params.properties.type = BLE_GAP_ADV_TYPE_CONNECTABLE_SCANNABLE_UNDIRECTED;
    adv_params.p_peer_addr     = NULL;
    adv_params.filter_policy   = BLE_GAP_ADV_FP_ANY;
    adv_params.interval        = APP_ADV_INTERVAL;

    err_code = sd_ble_gap_adv_set_configure(&m_adv_handle, &m_adv_data, &adv_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 write events to the LED characteristic.
 *
 * @param[in] p_lbs     Instance of LED Button Service to which the write applies.
 * @param[in] led_state Written/desired state of the LED.
 */
static void led_write_handler(uint16_t conn_handle, ble_lbs_t * p_lbs, uint8_t led_state)
{
    if (led_state)
    {
        bsp_board_led_on(LEDBUTTON_LED);
        NRF_LOG_INFO("Received LED ON!");
    }
    else
    {
        bsp_board_led_off(LEDBUTTON_LED);
        NRF_LOG_INFO("Received LED OFF!");
    }
}


/**@brief Function for initializing services that will be used by the application.
 */
static void services_init(void)
{
    ret_code_t         err_code;
    ble_lbs_init_t     init     = {0};
    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 LBS.
    init.led_write_handler = led_write_handler;

    err_code = ble_lbs_init(&m_lbs, &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 that
 *          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 advertising.
 */
static void advertising_start(void)
{
    ret_code_t           err_code;

    err_code = sd_ble_gap_adv_start(m_adv_handle, APP_BLE_CONN_CFG_TAG);
    APP_ERROR_CHECK(err_code);

    bsp_board_led_on(ADVERTISING_LED);
}


/**@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;

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

        case BLE_GAP_EVT_DISCONNECTED:
            NRF_LOG_INFO("Disconnected");
            bsp_board_led_off(CONNECTED_LED);
            m_conn_handle = BLE_CONN_HANDLE_INVALID;
            err_code = app_button_disable();
            APP_ERROR_CHECK(err_code);
            advertising_start();
            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_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_GATTS_EVT_SYS_ATTR_MISSING:
            // No system attributes have been stored.
            err_code = sd_ble_gatts_sys_attr_set(m_conn_handle, NULL, 0, 0);
            APP_ERROR_CHECK(err_code);
            break;

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

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

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


/**@brief Function for 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();
    if (err_code == NRF_ERROR_NO_MEM)
{
    // ram_start now contains the minimum required RAM start address
    NRF_LOG_INFO("Required RAM start: 0x%08X\r\n");
    // or use a breakpoint and check ram_start value
}
    NRF_LOG_INFO("error log is %d and %x",err_code,err_code);
    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 button handler module.
 *
 * @param[in] pin_no        The pin that the event applies to.
 * @param[in] button_action The button action (press/release).
 */
static void button_event_handler(uint8_t pin_no, uint8_t button_action)
{
    ret_code_t err_code;

    switch (pin_no)
    {
        case LEDBUTTON_BUTTON:
            NRF_LOG_INFO("Send button state change.");
            err_code = ble_lbs_on_button_change(m_conn_handle, &m_lbs, button_action);
            if (err_code != NRF_SUCCESS &&
                err_code != BLE_ERROR_INVALID_CONN_HANDLE &&
                err_code != NRF_ERROR_INVALID_STATE &&
                err_code != BLE_ERROR_GATTS_SYS_ATTR_MISSING)
            {
                APP_ERROR_CHECK(err_code);
            }
            break;

        default:
            APP_ERROR_HANDLER(pin_no);
            break;
    }
}


/**@brief Function for initializing the button handler module.
 */
static void buttons_init(void)
{
    ret_code_t err_code;

    //The array must be static because a pointer to it will be saved in the button handler module.
    static app_button_cfg_t buttons[] =
    {
        {LEDBUTTON_BUTTON, false, BUTTON_PULL, button_event_handler}
    };

    err_code = app_button_init(buttons, ARRAY_SIZE(buttons),
                               BUTTON_DETECTION_DELAY);
    APP_ERROR_CHECK(err_code);
}


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();
    }

}
void test_minimal_current(void) {
    // Disable DC-DC (since you don't have LFXO)

    
    // Disable all peripherals
    NRF_UART0->ENABLE = 0;
    NRF_GPIOTE->INTENCLR;
    NRF_SPIM0->ENABLE = 0;
    NRF_SPIM1->ENABLE = 0;
  //  NRF_SPIM2->ENABLE = 0;
    NRF_TWIM0->ENABLE = 0;
//    NRF_TWIM1->ENABLE = 0;
    
    // Configure all GPIOs
    for (uint8_t i = 0; i < 32; i++) {
        // Skip debug pins if you want to keep debugging
        if (i == 18 || i == 19) continue;
        
        nrf_gpio_cfg_input(i, NRF_GPIO_PIN_PULLDOWN);
    }
    
    for (uint8_t i = 0; i < 16; i++) {
        nrf_gpio_cfg_input(32 + i, NRF_GPIO_PIN_PULLDOWN);
    }
    
    // Enter System OFF mode (absolute lowest power)

}


/**@brief Function for application main entry.
 */
int main(void)
{
    // Initialize.
    /*
    log_init();
    leds_init();
    timers_init();
    buttons_init();
    power_management_init();
    ble_stack_init();
    gap_params_init();
    gatt_init();
    services_init();
    advertising_init();
    conn_params_init();

    // Start execution.
    NRF_LOG_INFO("Blinky example started.");
    advertising_start();
*/
    // Enter main loop.
    test_minimal_current();
    power_management_init();

    for (;;)
    {
        idle_state_handle();
    }
}


/**
 * @}
 */

[Simonr]

Hi

1. From the current consumption it seems that the floor current is ~3mA, which means that either the nRF52811 doesn't go to sleep correctly, or there is something else on the board that draws this excess current.

2. Most likely a PCB layout issue. Leakage current or some other chip drawing power.

3. No, except removing the inductors and capacitor from the DCC pin there should be no HW changes necessary.

4. I think the first step should be to do a HW review. We can help you with that if you'd like. If you update the schematics as a .pdf and HW layout as gerber files we can review it and see if something obvious seems off here. Are there for example any other chips/MCUs on your board that might be drawing current?

The next thing if we can't find anything in the HW files would be to debug the custom board physically and try to find out where this current disappears to. That would mainly be done with a multimeter of sorts while the device is running in what should be a low power mode and checking from which pin/decoupling cap the current escapes to.

Do you see the same behavior on more than one board or have you only tested on one specific custom board? Making sure it's reproducible on more than one board is a good way to see if this is just not a soldering issue.

Best regards,

Simon

[Purvesh patel]

Hi Simon,

Thank you for the quick response and suggestions!

Testing System OFF Mode

To isolate whether this is a hardware or firmware/configuration issue, is there a way to force the nRF52811 into System OFF mode to achieve absolute minimum current consumption? This would help determine if:

• Hardware issue: Current remains high (~3-4mA) even in deepest sleep → PCB/layout problem
• Configuration issue: Current drops significantly → Something in firmware keeping chip awake

I tried using this code to disable everything and force sleep, but I'm still seeing the same ~3.66mA consumption:

// UART
NRF_UART0->ENABLE = 0;

// SPI/SPIM
NRF_SPI0->ENABLE = 0;
NRF_SPIM0->ENABLE = 0;
NRF_SPIM1->ENABLE = 0;

// TWI/TWIM
NRF_TWI0->ENABLE = 0;
NRF_TWIM0->ENABLE = 0;

// Timers - CRITICAL for removing periodic wakeups
NRF_TIMER0->TASKS_STOP = 1;
NRF_TIMER0->TASKS_SHUTDOWN = 1;
NRF_TIMER1->TASKS_STOP = 1;
NRF_TIMER1->TASKS_SHUTDOWN = 1;
NRF_TIMER2->TASKS_STOP = 1;
NRF_TIMER2->TASKS_SHUTDOWN = 1;

// RTC
NRF_RTC0->TASKS_STOP = 1;
NRF_RTC1->TASKS_STOP = 1;

// GPIOTE
NRF_GPIOTE->INTENCLR = 0xFFFFFFFF;
for (int i = 0; i < 8; i++) {
    NRF_GPIOTE->CONFIG[i] = 0;
}

// Other peripherals
NRF_SAADC->ENABLE = 0;
NRF_PWM0->ENABLE = 0;
NRF_COMP->ENABLE = 0;
NRF_RADIO->POWER = 0;

// Stop clocks
NRF_CLOCK->TASKS_LFCLKSTOP = 1;
NRF_CLOCK->TASKS_HFCLKSTOP = 1;

// Disable DC/DC
NRF_POWER->DCDCEN = 0;
__disable_irq();
NVIC->ICPR[0] = 0xFFFFFFFF;

nrf_delay_ms(100);

// Sleep with WFE
while(1) {
    __WFE();
}

Result: Still seeing ~3.66mA, no change from normal operation.

Questions

1. How can I properly disable all GPIOs? Should I configure them as:
   • Input with pulldown?
   • Disconnected input buffer?
   • Something else for nRF52811 specifically?
2. Is there a recommended test sequence to enter absolute minimum power state (System OFF)?
3. Should I try entering System OFF mode directly using NRF_POWER->SYSTEMOFF = 1; to see the absolute floor current consumption?
   
   

edit:- on trying  this code
int main(void){
  NRF_POWER->SYSTEMOFF = 1;
  for(;;){}
}
in ble_blinky example i got this

[Simonr]

Hi

What SDK version are you working on here? As long as your project is not using a SoftDevice the NRF_POWER->SYSTEMOFF = 1; should power off the nRF52811 correctly if that's the only thing you want to test.

If the same project draws down in the micro amps on a DK but not on the custom board. You likely have the correct GPIO settings, and that points to this being a HW issue.

I think the first step should be to do a HW review. We can help you with that if you'd like. If you upload the schematics as a .pdf and HW layout as gerber files we can review it and see if something obvious seems off here.

Best regards,

Simon