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]

is 600uA acceptable for your use case?

[david]

 Hi Elias, 

       I had similar issue,did you find the way to resolve the  500uA  after stack is initialize (advertising  not work yet) ?

[Elias Löwe]

Hi David!

I can confirm, that Aryan's answer worked for me. I just changed #if 0 to #if 1

# file port_cmsis_systick.c

#if 1  // 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)

This did its job for demo project.

Also for this project I had to do few more things:

1. As far as I used floating point calculations, I had to chnage my main.c module as follows:

int main(void)
{
    NVIC_SetPriority(FPU_IRQn, APP_IRQ_PRIORITY_LOW);
    NVIC_EnableIRQ(FPU_IRQn);

    /* application code */
    ...
}

#define FPU_EXCEPTION_MASK 0x0000009F

void FPU_IRQHandler(void)
{
    uint32_t *fpscr = (uint32_t *)(FPU->FPCAR+0x40);
    (void)__get_FPSCR();

    *fpscr = *fpscr & ~(FPU_EXCEPTION_MASK);
}

2. We use SAADC module for some measurements and I had to uninitialise it after usage like this after each usage:

nrf_drv_saadc_uninit();
   
NRF_SAADC->INTENCLR = (SAADC_INTENCLR_END_Clear << SAADC_INTENCLR_END_Pos);

NVIC_ClearPendingIRQ(SAADC_IRQn);

And now average power consumption is about 30uA.

p.S. Sorry for late answer, so much work here...

[Eric Smith]

Hi Aryan,

I had reported excessive current consumed by the hrs_freertos demo in SDK 14.2 in private ticket 201725, opened March 7 2018. Another Nordic engineer asked me to try that #if 0, which solved the problem. Presumably that led to it being put it into SDK 15.

I find that even with SDK 15.0, if I change the code back to using sd_app_evt_wait(), I get an increase of 13mA in my application (derived from hrs_freertos). Whatever the underlying problem was in SDK 14.2 or S132 5.1.0, it does not seem to be fixed in SDK 15.0 or S132 6.0.0, so the workaround is still necessary.

Eric

[rahmat]

Hi Elias,

Just started with this board recently, still facing the 7mA issue. Are those the only changes you did? I still could not get it down to anywhere close to 30uA like yours. Thanks.

Regards,

Rahmat