Minimizing the power draw using System OFF and RAM retention

[lhochstetter]

Hi everyone,

I'm having an issue with the power draw of my application (SDK 15.0.0, SD 132 v6, Sparkfun nRF52832 Breakout). The application does roughly the following: it sleeps until it receives an GPIO interrupt (there are two different GPIOs which can wake up the application), does some (non connectable) advertising and resumes sleeping.

According to the data sheet of the nRF52832 0.7 µA are possible with full RAM retention and in system state System OFF. The power draw of my application exceeds this number (around ten times higher), however I'm not utilising the System OFF mode yet (currently using only the nrf_pwr_mgmt_run() function).

I did some research and discovered the sd_power_off() function. When I add the sd_power_off() function to my code, the system "freezes" / 'hangs" and draws about 10mA.

I did take a look at the example "ble_app_pwr_profiling" but it is rather complex - has anyone created / found a simpler solution (do some advertising, go to System OFF with RAM retention, wake up to an GPIO interrupt, repeat) yet?

How can I differentiate the two different GPIO interrupt sources when using them to wake up? (I want to count the times my application has woken up to sources 1 and 2)


Best,

lhochstetter

[Håkon Alseth]

Hi,

 

If you are using the nrf_pwr_mgmt library, you should call the appropriate API for entering system off mode:

nrf_pwr_mgmt_shutdown(NRF_PWR_MGMT_SHUTDOWN_GOTO_SYSOFF);

Are you debugging while trying to enter system off mode? Emulated systemoff (entering system off in debug mode) will not work as intended, as it will return immediately due to the debugger being attached.

Kind regards,

Håkon

[lhochstetter]

Hi,

sorry for the belated reply. I tried your suggestion (the board did go to some sort of power saving mode, drawing ~1mA but was unresponsive afterwards).

I spent some time studying the ble_app_pwr_profiling example. In the example two functions are used to go to the System OFF mode:

nrf_pwr_mgmt_shutdown(NRF_PWR_MGMT_SHUTDOWN_GOTO_SYSOFF)

and

sd_power_system_off()

Since sd_power_system_off() is used in the ble_evt_handler() I assume that this function is used when the Softdevice is / was active. nrf_pwr_mgmt_shutdown(NRF_PWR_MGMT_SHUTDOWN_GOTO_SYSOFF) is used otherwise.

Right now I'm trying to gut the ble_app_pwr_profiling example to get a simple non-connectable beacon which reacts to button presses, advertising the button pressed and the count of button presses, and returning to System OFF afterwards.

EDIT

I'm not debugging / There is no debugger attached

/EDIT

Best,

lhochstetter

[Håkon Alseth]

Hi,

 

Systemoff will generate a reset when you wake up, so the simplest logic is to check your GPIOs upon init, or reading the NRF_GPIO->LATCH register:

gpio_init();
// Check the GPIO states to see which one is still active
if (nrf_gpio_pin_read(my_pin) == ACTIVE_LEVEL) {
    do_something();
}

// Alternative is to read NRF_GPIO->LATCH register.
// See http://infocenter.nordicsemi.com/topic/com.nordic.infocenter.nrf52832.ps.v1.1/gpio.html#register.LATCH
// Write '1' to bitfields in register to clear it.

 

lhochstetter said:

When I use this snippet the system freezes up again and the voltage rises to a couple hundred mV (without I measure <20 mV when idling). Judging by the existance of the sd_power_ram_power_*() functions I assume that you have to use those to configure RAM retention but my attempts so far failed.

 When the softdevice is enabled, you shall not write directly to the NRF_POWER register, as this will create a fault-condition. You should rather use the sd_ prefixed function call. You can write the exact same bit pattern into the sd_power_ram_power_* function as you would to the NRF_POWER->RAMON register.

  

Kind regards,

Håkon

[lhochstetter]

Hi,

waking up from Sytem OFF using following snippets works just fine, thanks alot!

static void gpio_init(void)
{
	ret_code_t err_code;

	err_code = nrf_drv_gpiote_init();
	APP_ERROR_CHECK(err_code);

	nrf_drv_gpiote_out_config_t out_config = GPIOTE_CONFIG_OUT_SIMPLE(true);
	err_code = nrf_drv_gpiote_out_init(BSP_LED_0, &out_config);

	APP_ERROR_CHECK(err_code);
	err_code = nrf_drv_gpiote_out_init(BSP_LED_2, &out_config);

	nrf_gpio_cfg_sense_input(BSP_BUTTON_0, NRF_GPIO_PIN_PULLUP, NRF_GPIO_PIN_SENSE_LOW);
}

void main()
{
	uint32_t j = ((uint32_t *) (0x2000F000))[0];

	// Initialize.
	gpio_init();
	ble_stack_init();
    for (int i = 0; i < 8; i++) {
    	sd_power_ram_power_set(i,
    		                  (POWER_RAM_POWER_S0POWER_On << POWER_RAM_POWER_S0POWER_Pos)
    		                | (POWER_RAM_POWER_S1POWER_On << POWER_RAM_POWER_S1POWER_Pos)
    		                | (POWER_RAM_POWER_S0RETENTION_On << POWER_RAM_POWER_S0RETENTION_Pos)
    		                | (POWER_RAM_POWER_S1RETENTION_On << POWER_RAM_POWER_S1RETENTION_Pos));
    }
	if (0 == nrf_gpio_pin_read(BSP_BUTTON_0)) {
		nrf_drv_gpiote_out_clear(BSP_LED_0);
	}

	if (3 == j) {
		nrf_drv_gpiote_out_clear(BSP_LED_2);
		j = 0;
	}

	j++;
	((uint32_t *) (0x2000F000))[0] = j;

	nrf_delay_ms(1000);

	nrf_drv_gpiote_out_set(BSP_LED_0);
	nrf_drv_gpiote_out_set(BSP_LED_2);

	sd_power_system_off();


	for(;;) {
		sd_app_evt_wait();
	}
}

However, RAM retention doesn't (again using above shown snippets). I'm trying to retain the entire RAM of the nRF52832, but it seems that my for loop doesn't do it's job. I tried to only set the 7th RAM tile (both sections) but to no avail.

What am I missing?

Another question in the very same project popped up: I'm seeing 15-20mV spikes in intervals of around 45ms when advertising / when sd_app_evt_wait() is running.

Could it be that some scanning related code is running in the background / softdevice in between advertisements? (I've largely adapted the ble_peripheral / ble_app_beacon example, but I'd argue that the scanning functionality isn't configured / started).

Kind regards,

lhochstetter

[Håkon Alseth]

Hello,

 

lhochstetter said:

Another question in the very same project popped up: I'm seeing 15-20mV spikes in intervals of around 45ms when advertising / when sd_app_evt_wait() is running.

These are due to the regulator refresh mode: https://devzone.nordicsemi.com/f/nordic-q-a/20121/periodic-current-during-waiting-event

I assume you're using a 10 ohm resistor (1.5 to 2 mA) to monitor the current.

lhochstetter said:

However, RAM retention doesn't (again using above shown snippets). I'm trying to retain the entire RAM of the nRF52832, but it seems that my for loop doesn't do it's job. I tried to only set the 7th RAM tile (both sections) but to no avail.

What am I missing?

 

Pointing to a specific address is not a recommended approach, as you do not know if there's anything there already, like the .stack or .heap section. See this thread and the linked threads for more information on ram retention after system off:

https://devzone.nordicsemi.com/f/nordic-q-a/36848/nrf52840-ram-retention-example-fails-with-max_test_iterations-1

Kind regards,

Håkon

[lhochstetter]

Hi,

thanks for the link, I tried to merge your example (the gcc one) with mine, but sadly it didn't work out i.e. the value was not retained. Again I'm trying to only save the second slave of the 7th RAM tile.

Code snippets:

uint32_t j __attribute__((section(".no_init"))) __attribute__((used));

int main(void)
{
	// Initialize.
	gpio_init();
	ble_stack_init();

	sd_power_ram_power_set(7, (POWER_RAM_POWER_S1POWER_On << POWER_RAM_POWER_S1POWER_Pos)
		                | (POWER_RAM_POWER_S1RETENTION_On << POWER_RAM_POWER_S1RETENTION_Pos));

	if (0 == nrf_gpio_pin_read(BSP_BUTTON_0)) {
		nrf_drv_gpiote_out_clear(BSP_LED_0);
	}

	if (3 == j) {
		nrf_drv_gpiote_out_clear(BSP_LED_2);
		j = 0;
	}

	j++;
	nrf_delay_ms(1000);
	nrf_drv_gpiote_out_set(BSP_LED_0);
	nrf_drv_gpiote_out_set(BSP_LED_2);
	sd_power_system_off();

	for(;;) {
		idle_state_handle();
	}

}

My linker file (based on the original ble_app_beacon) which I tied to merge with the linker file provided in your example.

/* Linker script to configure memory regions. */

SEARCH_DIR(.)
GROUP(-lgcc -lc -lnosys)

MEMORY
{
  FLASH (rx) : ORIGIN = 0x26000, LENGTH = 0x5a000
  RAM (rwx) :  ORIGIN = 0x200018a8, LENGTH = 0xd758
  NO_INIT (rwx) :  ORIGIN = 0x2000F000, LENGTH = 0x1000
}

SECTIONS
{
  .no_init (NOLOAD):
  {
    PROVIDE(__start_no_init_data = .);
	KEEP(*(SORT(.no_init*)))
	PROVIDE(__stop_no_init_data = .);
  } > NO_INIT
}

SECTIONS
{
  . = ALIGN(4);
  .mem_section_dummy_ram :
  {
  }
  .log_dynamic_data :
  {
    PROVIDE(__start_log_dynamic_data = .);
    KEEP(*(SORT(.log_dynamic_data*)))
    PROVIDE(__stop_log_dynamic_data = .);
  } > RAM
  .cli_sorted_cmd_ptrs :
  {
    PROVIDE(__start_cli_sorted_cmd_ptrs = .);
    KEEP(*(.cli_sorted_cmd_ptrs))
    PROVIDE(__stop_cli_sorted_cmd_ptrs = .);
  } > RAM
  .fs_data :
  {
    PROVIDE(__start_fs_data = .);
    KEEP(*(.fs_data))
    PROVIDE(__stop_fs_data = .);
  } > RAM

} INSERT AFTER .data;

SECTIONS
{
  .mem_section_dummy_rom :
  {
  }
  .sdh_soc_observers :
  {
    PROVIDE(__start_sdh_soc_observers = .);
    KEEP(*(SORT(.sdh_soc_observers*)))
    PROVIDE(__stop_sdh_soc_observers = .);
  } > FLASH
  .sdh_ble_observers :
  {
    PROVIDE(__start_sdh_ble_observers = .);
    KEEP(*(SORT(.sdh_ble_observers*)))
    PROVIDE(__stop_sdh_ble_observers = .);
  } > FLASH
  .pwr_mgmt_data :
  {
    PROVIDE(__start_pwr_mgmt_data = .);
    KEEP(*(SORT(.pwr_mgmt_data*)))
    PROVIDE(__stop_pwr_mgmt_data = .);
  } > FLASH
  .log_const_data :
  {
    PROVIDE(__start_log_const_data = .);
    KEEP(*(SORT(.log_const_data*)))
    PROVIDE(__stop_log_const_data = .);
  } > FLASH
    .nrf_balloc :
  {
    PROVIDE(__start_nrf_balloc = .);
    KEEP(*(.nrf_balloc))
    PROVIDE(__stop_nrf_balloc = .);
  } > FLASH
  .sdh_state_observers :
  {
    PROVIDE(__start_sdh_state_observers = .);
    KEEP(*(SORT(.sdh_state_observers*)))
    PROVIDE(__stop_sdh_state_observers = .);
  } > FLASH
  .sdh_stack_observers :
  {
    PROVIDE(__start_sdh_stack_observers = .);
    KEEP(*(SORT(.sdh_stack_observers*)))
    PROVIDE(__stop_sdh_stack_observers = .);
  } > FLASH
  .sdh_req_observers :
  {
    PROVIDE(__start_sdh_req_observers = .);
    KEEP(*(SORT(.sdh_req_observers*)))
    PROVIDE(__stop_sdh_req_observers = .);
  } > FLASH
    .nrf_queue :
  {
    PROVIDE(__start_nrf_queue = .);
    KEEP(*(.nrf_queue))
    PROVIDE(__stop_nrf_queue = .);
  } > FLASH
    .cli_command :
  {
    PROVIDE(__start_cli_command = .);
    KEEP(*(.cli_command))
    PROVIDE(__stop_cli_command = .);
  } > FLASH
  .crypto_data :
  {
    PROVIDE(__start_crypto_data = .);
    KEEP(*(SORT(.crypto_data*)))
    PROVIDE(__stop_crypto_data = .);
  } > FLASH

} INSERT AFTER .text

INCLUDE "nrf_common.ld"

Sorry for making you basically hold my hand but I'm fairly ignorant when it comes to the SDK and how things work / are compiled ... is there by chance an introduction / tutorial which explains the SDK structure etc. ? (I'm also at a loss when it comes to tracking down function definitions etc.)

I tried to compile your example but it kept complaining, that some files where missing - the ../../config directory does not seem to be in the .zip. I'm also guessing that your example was written with an older SDK version as system_nrf52.c seems to have changed places.

Kind regards,

lhochstetter

[Håkon Alseth]

Hi,

 

I integrated the previous example into ble_app_beacon (quick and dirty, my apologies), here's the main file and linker file (SDK v15.2):

ble_app_beacon_gcc_nrf52.ld

Fullscreen main.c Download

/**
 * Copyright (c) 2014 - 2018, Nordic Semiconductor ASA
 *
 * All rights reserved.
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 * Redistribution and use in source and binary forms, with or without modification,
 * are permitted provided that the following conditions are met:
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 * 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
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 *    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.
 *
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 *    engineered, decompiled, modified and/or disassembled.
 *
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 * 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
 * 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.
 *
 */
/** @file
 *
 * @defgroup ble_sdk_app_beacon_main main.c
 * @{
 * @ingroup ble_sdk_app_beacon
 * @brief Beacon Transmitter Sample Application main file.
 *
 * This file contains the source code for an Beacon transmitter sample application.
 */

#include <stdbool.h>
#include <stdint.h>
#include "nordic_common.h"
#include "bsp.h"
#include "nrf_soc.h"
#include "nrf_sdh.h"
#include "nrf_sdh_ble.h"
#include "ble_advdata.h"
#include "app_timer.h"
#include "nrf_pwr_mgmt.h"

#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 NON_CONNECTABLE_ADV_INTERVAL    MSEC_TO_UNITS(100, UNIT_0_625_MS)  /**< The advertising interval for non-connectable advertisement (100 ms). This value can vary between 100ms to 10.24s). */

#define APP_BEACON_INFO_LENGTH          0x17                               /**< Total length of information advertised by the Beacon. */
#define APP_ADV_DATA_LENGTH             0x15                               /**< Length of manufacturer specific data in the advertisement. */
#define APP_DEVICE_TYPE                 0x02                               /**< 0x02 refers to Beacon. */
#define APP_MEASURED_RSSI               0xC3                               /**< The Beacon's measured RSSI at 1 meter distance in dBm. */
#define APP_COMPANY_IDENTIFIER          0x0059                             /**< Company identifier for Nordic Semiconductor ASA. as per www.bluetooth.org. */
#define APP_MAJOR_VALUE                 0x01, 0x02                         /**< Major value used to identify Beacons. */
#define APP_MINOR_VALUE                 0x03, 0x04                         /**< Minor value used to identify Beacons. */
#define APP_BEACON_UUID                 0x01, 0x12, 0x23, 0x34, \
                                        0x45, 0x56, 0x67, 0x78, \
                                        0x89, 0x9a, 0xab, 0xbc, \
                                        0xcd, 0xde, 0xef, 0xf0            /**< Proprietary UUID for Beacon. */

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

#if defined(USE_UICR_FOR_MAJ_MIN_VALUES)
#define MAJ_VAL_OFFSET_IN_BEACON_INFO   18                                 /**< Position of the MSB of the Major Value in m_beacon_info array. */
#define UICR_ADDRESS                    0x10001080                         /**< Address of the UICR register used by this example. The major and minor versions to be encoded into the advertising data will be picked up from this location. */
#endif

static ble_gap_adv_params_t m_adv_params;                                  /**< Parameters to be passed to the stack when starting advertising. */
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. */

/**@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 = NULL,
        .len    = 0

    }
};


static uint8_t m_beacon_info[APP_BEACON_INFO_LENGTH] =                    /**< Information advertised by the Beacon. */
{
    APP_DEVICE_TYPE,     // Manufacturer specific information. Specifies the device type in this
                         // implementation.
    APP_ADV_DATA_LENGTH, // Manufacturer specific information. Specifies the length of the
                         // manufacturer specific data in this implementation.
    APP_BEACON_UUID,     // 128 bit UUID value.
    APP_MAJOR_VALUE,     // Major arbitrary value that can be used to distinguish between Beacons.
    APP_MINOR_VALUE,     // Minor arbitrary value that can be used to distinguish between Beacons.
    APP_MEASURED_RSSI    // Manufacturer specific information. The Beacon's measured TX power in
                         // this implementation.
};


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

/**@brief Function for 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)
{
    uint32_t      err_code;
    ble_advdata_t advdata;
    uint8_t       flags = BLE_GAP_ADV_FLAG_BR_EDR_NOT_SUPPORTED;

    ble_advdata_manuf_data_t manuf_specific_data;

    manuf_specific_data.company_identifier = APP_COMPANY_IDENTIFIER;

#if defined(USE_UICR_FOR_MAJ_MIN_VALUES)
    // If USE_UICR_FOR_MAJ_MIN_VALUES is defined, the major and minor values will be read from the
    // UICR instead of using the default values. The major and minor values obtained from the UICR
    // are encoded into advertising data in big endian order (MSB First).
    // To set the UICR used by this example to a desired value, write to the address 0x10001080
    // using the nrfjprog tool. The command to be used is as follows.
    // nrfjprog --snr <Segger-chip-Serial-Number> --memwr 0x10001080 --val <your major/minor value>
    // For example, for a major value and minor value of 0xabcd and 0x0102 respectively, the
    // the following command should be used.
    // nrfjprog --snr <Segger-chip-Serial-Number> --memwr 0x10001080 --val 0xabcd0102
    uint16_t major_value = ((*(uint32_t *)UICR_ADDRESS) & 0xFFFF0000) >> 16;
    uint16_t minor_value = ((*(uint32_t *)UICR_ADDRESS) & 0x0000FFFF);

    uint8_t index = MAJ_VAL_OFFSET_IN_BEACON_INFO;

    m_beacon_info[index++] = MSB_16(major_value);
    m_beacon_info[index++] = LSB_16(major_value);

    m_beacon_info[index++] = MSB_16(minor_value);
    m_beacon_info[index++] = LSB_16(minor_value);
#endif

    manuf_specific_data.data.p_data = (uint8_t *) m_beacon_info;
    manuf_specific_data.data.size   = APP_BEACON_INFO_LENGTH;

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

    advdata.name_type             = BLE_ADVDATA_NO_NAME;
    advdata.flags                 = flags;
    advdata.p_manuf_specific_data = &manuf_specific_data;

    // Initialize advertising parameters (used when starting advertising).
    memset(&m_adv_params, 0, sizeof(m_adv_params));

    m_adv_params.properties.type = BLE_GAP_ADV_TYPE_NONCONNECTABLE_NONSCANNABLE_UNDIRECTED;
    m_adv_params.p_peer_addr     = NULL;    // Undirected advertisement.
    m_adv_params.filter_policy   = BLE_GAP_ADV_FP_ANY;
    m_adv_params.interval        = NON_CONNECTABLE_ADV_INTERVAL;
    m_adv_params.duration        = 0;       // Never time out.

    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 = sd_ble_gap_adv_set_configure(&m_adv_handle, &m_adv_data, &m_adv_params);
    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);

    err_code = bsp_indication_set(BSP_INDICATE_ADVERTISING);
    APP_ERROR_CHECK(err_code);
}


/**@brief Function for initializing the BLE stack.
 *
 * @details Initializes the SoftDevice and the BLE event interrupt.
 */
static void ble_stack_init(void)
{
    ret_code_t err_code;

    err_code = nrf_sdh_enable_request();
    APP_ERROR_CHECK(err_code);

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

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


/**@brief Function for initializing logging. */
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 LEDs. */
static void leds_init(void)
{
    ret_code_t err_code = bsp_init(BSP_INIT_LEDS, NULL);
    APP_ERROR_CHECK(err_code);
}


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


/**@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();
    }
}

#include "nrf_delay.h"

uint32_t test __attribute__((section(".no_init"))) __attribute__((used));

/**
 * @brief Function for application main entry.
 */
int main(void)
{
    // Initialize.
    log_init();
    timers_init();
    leds_init();
    power_management_init();
    /*for (int i = 0; i < 8; i++)
      NRF_POWER->RAM[i].POWER = 0xFFFFFFFF;
      */
    ble_stack_init();
    advertising_init();
    sd_power_ram_power_set(7, (POWER_RAM_POWER_S1RETENTION_On << POWER_RAM_POWER_S1RETENTION_Pos));
    nrf_gpio_cfg_sense_input(13, NRF_GPIO_PIN_PULLUP,NRF_GPIO_PIN_SENSE_LOW);

    if (test > 0)
    {
        uint8_t led_state = test % 4;
        nrf_gpio_pin_toggle(BSP_LED_0 + led_state);               
        nrf_delay_us(100*1000);
    } 
    test++;    
    sd_power_system_off();

    // Start execution.
    NRF_LOG_INFO("Beacon example started.");
    advertising_start();

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


/**
 * @}
 */

I didn't have any problems running this code, it loops through the LEDs like it should. Could you try this and see if that works?

 

Kind regards,

Håkon

[lhochstetter]

Hi Håkon,

it just works (tm)! Thank you!

I took a closer look at your .ld and .c files and noticed some differences:

In the .ld file you "included" the no_init declaration in the section which was to be "inserted after .text" (if I understand the .ld file correctly). I used the "spare" section at the very beginning without the "INSERT AFTER ..." command.

I therefore suspect that my main issue was the no_init declaration at the wrong section.

In the .c file / in the main function you "only enabled RAM retention" and did not touch the "POWER_RAM_POWER_S1POWER_On register" at all.

One more question: could you provide me with a couple terms to research, so I can properly understand the .ld files syntax / notation?

Thanks again!

Kind regards,

lhochstetter

[Håkon Alseth]

Hi lhochstetter,

 

Glad to hear that it worked.

You do not need to set the "POWER_RAM_POWER_S1POWER_On" field, as it is already set (reset value is '1').

 

Regarding the .ld scripts and syntax, this is given by the toolchain: https://sourceware.org/binutils/docs/ld/Scripts.html

You may find better ways of describing the linker scripts, I'd recommend searching around and checking on stack overflow etc. to see if you can find any resources there.

 

Kind regards,

Håkon

[lhochstetter]

Hi Håkon,

thanks for the link and hints!

I'll mark your 'quick and dirty' solution as answer as it was quite helpful.

Kind regards,

lhochstetter