High power consumption of softdevice

[Elias Löwe]

Hello!

I am working on firmware for device that has freertos in the base and implements BLE beacon and 1 service with 7 characteristics. Everything works. But power consumption is too high.

After plenty of tests on final HW, I've created playground based on ble_app_hrs_freertos_pca10040_s132 sample project and switched to sparkfun board.

When have just FreeRTOS with no user-defined tasks, consumption is about 1uA.

After I call  ble_stack_init with code below, I got about 500uA. It is without advertising at all.

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);
}

When beacon is enabled I have cca 650uA.

When GATT and beacon are working I have cca 750uA.

I measure with multimeter.

Results seems fine for me except for those 500uA after stack is initialized. Why is it so high? What can I do to lower it?

• SDK v 15.0
• NRF_LOG_ENABLED is 0
• Using RELEASE configuration.
• Tried S132 and S140 - result is the same

[Susheel Nuguru]

Hi Elias, 

What are the clock configurations you are using? When you enable the softdevice, it will start RTC0 as a house keeping timer. This needs LFCLK.

[Elias Löwe]

Hi Aryan,

I use defaults from ble_app_hrs_freertos_pca10040_s132 example.

// <e> NRFX_RTC_ENABLED - nrfx_rtc - RTC peripheral driver
//==========================================================
#ifndef NRFX_RTC_ENABLED
#define NRFX_RTC_ENABLED 0
#endif
// <q> NRFX_RTC0_ENABLED  - Enable RTC0 instance
 

#ifndef NRFX_RTC0_ENABLED
#define NRFX_RTC0_ENABLED 0
#endif

// <q> NRFX_RTC1_ENABLED  - Enable RTC1 instance
 

#ifndef NRFX_RTC1_ENABLED
#define NRFX_RTC1_ENABLED 0
#endif

// <q> NRFX_RTC2_ENABLED  - Enable RTC2 instance
 

#ifndef NRFX_RTC2_ENABLED
#define NRFX_RTC2_ENABLED 0
#endif

// <o> NRFX_RTC_MAXIMUM_LATENCY_US - Maximum possible time[us] in highest priority interrupt 
#ifndef NRFX_RTC_MAXIMUM_LATENCY_US
#define NRFX_RTC_MAXIMUM_LATENCY_US 2000
#endif

// <o> NRFX_RTC_DEFAULT_CONFIG_FREQUENCY - Frequency  <16-32768> 


#ifndef NRFX_RTC_DEFAULT_CONFIG_FREQUENCY
#define NRFX_RTC_DEFAULT_CONFIG_FREQUENCY 32768
#endif

// <q> NRFX_RTC_DEFAULT_CONFIG_RELIABLE  - Ensures safe compare event triggering
 

#ifndef NRFX_RTC_DEFAULT_CONFIG_RELIABLE
#define NRFX_RTC_DEFAULT_CONFIG_RELIABLE 0
#endif

// <o> NRFX_RTC_DEFAULT_CONFIG_IRQ_PRIORITY  - Interrupt priority
 
// <0=> 0 (highest) 
// <1=> 1 
// <2=> 2 
// <3=> 3 
// <4=> 4 
// <5=> 5 
// <6=> 6 
// <7=> 7 

#ifndef NRFX_RTC_DEFAULT_CONFIG_IRQ_PRIORITY
#define NRFX_RTC_DEFAULT_CONFIG_IRQ_PRIORITY 7
#endif

// <e> NRFX_RTC_CONFIG_LOG_ENABLED - Enables logging in the module.
//==========================================================
#ifndef NRFX_RTC_CONFIG_LOG_ENABLED
#define NRFX_RTC_CONFIG_LOG_ENABLED 0
#endif
// <o> NRFX_RTC_CONFIG_LOG_LEVEL  - Default Severity level
 
// <0=> Off 
// <1=> Error 
// <2=> Warning 
// <3=> Info 
// <4=> Debug 

#ifndef NRFX_RTC_CONFIG_LOG_LEVEL
#define NRFX_RTC_CONFIG_LOG_LEVEL 3
#endif

// <o> NRFX_RTC_CONFIG_INFO_COLOR  - ANSI escape code prefix.
 
// <0=> Default 
// <1=> Black 
// <2=> Red 
// <3=> Green 
// <4=> Yellow 
// <5=> Blue 
// <6=> Magenta 
// <7=> Cyan 
// <8=> White 

#ifndef NRFX_RTC_CONFIG_INFO_COLOR
#define NRFX_RTC_CONFIG_INFO_COLOR 0
#endif

// <o> NRFX_RTC_CONFIG_DEBUG_COLOR  - ANSI escape code prefix.
 
// <0=> Default 
// <1=> Black 
// <2=> Red 
// <3=> Green 
// <4=> Yellow 
// <5=> Blue 
// <6=> Magenta 
// <7=> Cyan 
// <8=> White 

#ifndef NRFX_RTC_CONFIG_DEBUG_COLOR
#define NRFX_RTC_CONFIG_DEBUG_COLOR 0
#endif

Anything else I can provide?

[Susheel Nuguru]

I think i found the problem.

It is in port_cmsis_systick.c

#if 0  // With FreeRTOS sd_app_evt_wait increases power consumption with FreeRTOS compared to _WFE (NRFFOSDK-11174)
#ifdef SOFTDEVICE_PRESENT
            if (nrf_sdh_is_enabled())
            {
                uint32_t err_code = sd_app_evt_wait();
                APP_ERROR_CHECK(err_code);
            }
            else
#endif
#endif // (NRFFOSDK-11174)

I do not remember the exact way i came to a conclusion that sd_app_evt_wait was consuming more power with freertos. Hence I created an internal ticket NRFFOSDK-11174 to investigate why this happened. I remembered that i was reading more power with freertos and using sd_wait function. While using WFI it was less. This technically did not make sense, but i decided to comment out sd_app_evt_wait function until i get more results. But I am not able to reproduce this anymore. So i think this comment is the problem on SDK 15.

Please change line 231 in port_cmsis_systick.c to below

#ifdef SOFTDEVICE_PRESENT
            if (nrf_sdh_is_enabled())
            {
                uint32_t err_code = sd_app_evt_wait();
                APP_ERROR_CHECK(err_code);
            }
            else
#endif

I will try to push these changes to official SDK for the next release.

[Elias Löwe]

I tried this actualy...

If I use  sd_app_evt_wait(), then average consumption is about 7mA (without DCDC) and 5mA (with DCDC enabled).

Something is definitely wrong there.

[Elias Löwe]

But on Sparkfun with demo app it dropped down to cca 200uA

[Susheel Nuguru]

the average power consumption with connected state? debugger on?

[Elias Löwe]

while advertizing

debugger off