High power after starting SAADC and softdevice

Question

Hi everyone,

after a few days of analysis, I was able to find out what is the problem making my board consume a lot when idle.

I use SDK 15.0.0, softdevice S132 and a custom board with a few hardware (TWI and SAADC). BLE is not advertising for the moment.

If I run my code without using the SAADC, I have an idle consumption of 2-3 uA, which is perfect. I have periodic readings from the TWI and

all works fine.

As soon as I enable the SAADC, after I receive the first callback with correct data, the idle consumption become of about 470uA, and it never goes down.

I declared, as said in some discussions, the following in sdk.config

#ifndef NRFX_SAADC_CONFIG_LP_MODE
#define NRFX_SAADC_CONFIG_LP_MODE 1
#endif

and in the saadc_callback, I call uninit and I clear all the interrupts. My code is the following

void saadc_callback(nrf_drv_saadc_evt_t const * p_event)
{


    if (p_event->type == NRF_DRV_SAADC_EVT_DONE)
    {

        ret_code_t err_code;

        err_code = nrf_drv_saadc_buffer_convert(p_event->data.done.p_buffer, NUM_SAMPLES);
        APP_ERROR_CHECK(err_code);

        int i;
        for (i = 0; i < NUM_SAMPLES; i++)
        {
            NRF_LOG_INFO("SAADC Sample: %d", p_event->data.done.p_buffer[i]);
        } 

    }

    nrf_drv_saadc_abort();
    nrf_drv_saadc_uninit();
        NRF_SAADC->INTENCLR = (SAADC_INTENCLR_END_Clear << SAADC_INTENCLR_END_Pos);               //Disable the SAADC interrupt

		NVIC_DisableIRQ( SAADC_IRQn );
        NVIC_ClearPendingIRQ(SAADC_IRQn);    
        NRF_CLOCK->TASKS_HFCLKSTOP;



}

I tried all the possible combinations for disabling the SAADC, without success.

So, my question is: how can I get rid of these 470uA of extra consumption? I suspect that somehow they come from the HFCLK, which for some reason is activated when reading

from the saadc, but if I understood correctly, the softdevice should manage the HFCLK by itself, right?

I also post my saadc_init code

void saadc_init(void)
{
    ret_code_t err_code;    


    nrf_saadc_channel_config_t pressure_channel_config =
        NRF_DRV_SAADC_DEFAULT_CHANNEL_CONFIG_SE(NRF_SAADC_INPUT_AIN1);     
        pressure_channel_config.gain = NRF_SAADC_GAIN1_6;
        pressure_channel_config.reference  = NRF_SAADC_REFERENCE_INTERNAL;
        pressure_channel_config.burst = NRF_SAADC_BURST_ENABLED;
        pressure_channel_config.acq_time = NRF_SAADC_ACQTIME_10US;
        pressure_channel_config.pin_n = NRF_SAADC_INPUT_DISABLED;
        pressure_channel_config.resistor_n = NRF_SAADC_RESISTOR_DISABLED;
        pressure_channel_config.resistor_p = NRF_SAADC_RESISTOR_DISABLED;
        err_code = nrf_drv_saadc_init(NULL, saadc_callback);

        err_code = nrf_drv_saadc_channel_init(0, &pressure_channel_config);
        err_code = nrf_drv_saadc_buffer_convert(m_buffer_pool[0], PH_NUM_SAMPLES);
        err_code = nrf_drv_saadc_buffer_convert(m_buffer_pool[1], PH_NUM_SAMPLES);

    APP_ERROR_CHECK(err_code);
      

}