ADC CURRENT CONSUMPTION IS 3 TO 4mA, even in datasheet it is 700uA

RE: ADC CURRENT CONSUMPTION IS 3 TO 4mA, even in datasheet it is 700uA

Jared — Wed, 18 Jan 2023 14:42:12 GMT

Hi there,

So I think I've misunderstood you previously, I'm, sorry for that.

I've measured with your hex and can confirm that I measure about 3 mA on my development kit. I'm not sure why you're measuring that high if the delay isn't added which would mean that the program goes straight to nrfx_saadc_uninit, but I was able to get the current down to 16 µA by using the SAADC example in the nRF5SDK and modifying it a bit by un initializing PPI, the SAADC and the Timer after 5 samples (see the code below).

But to your main question, I guess what you're looking for is a low power SAADC example. Luckily, we already have this here.

I hope that helps.

regards

Jared

#include <stdbool.h>
#include <stdint.h>
#include <stdio.h>
#include <string.h>
#include "nrf.h"
#include "nrf_drv_saadc.h"
#include "nrf_drv_ppi.h"
#include "nrf_drv_timer.h"
#include "boards.h"
#include "app_error.h"
#include "nrf_delay.h"
#include "app_util_platform.h"
#include "nrf_pwr_mgmt.h"

#include "nrf_log.h"
#include "nrf_log_ctrl.h"
#include "nrf_log_default_backends.h"

#define SAMPLES_IN_BUFFER 5
volatile uint8_t state = 1;

static const nrf_drv_timer_t m_timer = NRF_DRV_TIMER_INSTANCE(0);
static nrf_saadc_value_t     m_buffer_pool[2][SAMPLES_IN_BUFFER];
static nrf_ppi_channel_t     m_ppi_channel;
static uint32_t              m_adc_evt_counter;


void timer_handler(nrf_timer_event_t event_type, void * p_context)
{

}


void saadc_sampling_event_init(void)
{
    ret_code_t err_code;

    err_code = nrf_drv_ppi_init();
    APP_ERROR_CHECK(err_code);

    nrf_drv_timer_config_t timer_cfg = NRF_DRV_TIMER_DEFAULT_CONFIG;
    timer_cfg.bit_width = NRF_TIMER_BIT_WIDTH_32;
    err_code = nrf_drv_timer_init(&m_timer, &timer_cfg, timer_handler);
    APP_ERROR_CHECK(err_code);

    /* setup m_timer for compare event every 400ms */
    uint32_t ticks = nrf_drv_timer_ms_to_ticks(&m_timer, 400);
    nrf_drv_timer_extended_compare(&m_timer,
                                   NRF_TIMER_CC_CHANNEL0,
                                   ticks,
                                   NRF_TIMER_SHORT_COMPARE0_CLEAR_MASK,
                                   false);
    nrf_drv_timer_enable(&m_timer);

    uint32_t timer_compare_event_addr = nrf_drv_timer_compare_event_address_get(&m_timer,
                                                                                NRF_TIMER_CC_CHANNEL0);
    uint32_t saadc_sample_task_addr   = nrf_drv_saadc_sample_task_get();

    /* setup ppi channel so that timer compare event is triggering sample task in SAADC */
    err_code = nrf_drv_ppi_channel_alloc(&m_ppi_channel);
    APP_ERROR_CHECK(err_code);

    err_code = nrf_drv_ppi_channel_assign(m_ppi_channel,
                                          timer_compare_event_addr,
                                          saadc_sample_task_addr);
    APP_ERROR_CHECK(err_code);
}


void saadc_sampling_event_enable(void)
{
    ret_code_t err_code = nrf_drv_ppi_channel_enable(m_ppi_channel);

    APP_ERROR_CHECK(err_code);
}


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, SAMPLES_IN_BUFFER);
        APP_ERROR_CHECK(err_code);

        int i;
        //NRF_LOG_INFO("ADC event number: %d", (int)m_adc_evt_counter);

        for (i = 0; i < SAMPLES_IN_BUFFER; i++)
        {
            NRF_LOG_INFO("%d", p_event->data.done.p_buffer[i]);
        }
        m_adc_evt_counter++;
    }
}


void saadc_init(void)
{
    ret_code_t err_code;
    nrf_saadc_channel_config_t channel_config =
        NRF_DRV_SAADC_DEFAULT_CHANNEL_CONFIG_SE(NRF_SAADC_INPUT_AIN0);

    err_code = nrf_drv_saadc_init(NULL, saadc_callback);
    APP_ERROR_CHECK(err_code);

    err_code = nrf_drv_saadc_channel_init(0, &channel_config);
    APP_ERROR_CHECK(err_code);

    err_code = nrf_drv_saadc_buffer_convert(m_buffer_pool[0], SAMPLES_IN_BUFFER);
    APP_ERROR_CHECK(err_code);

    err_code = nrf_drv_saadc_buffer_convert(m_buffer_pool[1], SAMPLES_IN_BUFFER);
    APP_ERROR_CHECK(err_code);

}

void saadc_init(void)
{
    ret_code_t err_code;
    nrf_saadc_channel_config_t channel_config =
        NRF_DRV_SAADC_DEFAULT_CHANNEL_CONFIG_SE(NRF_SAADC_INPUT_AIN0);

    err_code = nrf_drv_saadc_init(NULL, saadc_callback);
    APP_ERROR_CHECK(err_code);

    err_code = nrf_drv_saadc_channel_init(0, &channel_config);
    APP_ERROR_CHECK(err_code);

    err_code = nrf_drv_saadc_buffer_convert(m_buffer_pool[0], SAMPLES_IN_BUFFER);
    APP_ERROR_CHECK(err_code);

    err_code = nrf_drv_saadc_buffer_convert(m_buffer_pool[1], SAMPLES_IN_BUFFER);
    APP_ERROR_CHECK(err_code);

}


/**
 * @brief Function for main application entry.
 */
int main(void)
{
    //uint32_t err_code = NRF_LOG_INIT(NULL);
    //APP_ERROR_CHECK(err_code);

    //NRF_LOG_DEFAULT_BACKENDS_INIT();

    ret_code_t ret_code = nrf_pwr_mgmt_init();
    APP_ERROR_CHECK(ret_code);

    saadc_init();
    saadc_sampling_event_init();
    saadc_sampling_event_enable();
    //NRF_LOG_INFO("SAADC HAL simple example started.");

    while (1)
    {

        if(m_adc_evt_counter >= 5)
        {
          nrf_drv_ppi_channel_disable(m_ppi_channel);
          nrf_drv_saadc_uninit();
          nrf_drv_timer_uninit(&m_timer);
        
        }
        nrf_pwr_mgmt_run();
        //NRF_LOG_FLUSH();
    }
}

RE: ADC CURRENT CONSUMPTION IS 3 TO 4mA, even in datasheet it is 700uA

Embel_Tech — Wed, 18 Jan 2023 05:34:36 GMT

Yes.

we are using custom board .

Can you share any snap of that .

RE: ADC CURRENT CONSUMPTION IS 3 TO 4mA, even in datasheet it is 700uA

Jared — Tue, 17 Jan 2023 12:41:10 GMT

Hi,

I used the PPK2 and a development kit and configured the device and PPK in source mode. Yes, I measured 700 µA.

Are you using a custom board or development kit?

regards

Jared

RE: ADC CURRENT CONSUMPTION IS 3 TO 4mA, even in datasheet it is 700uA

Embel_Tech — Mon, 16 Jan 2023 13:19:46 GMT

how you measured current?

how you said its 700uA???

RE: ADC CURRENT CONSUMPTION IS 3 TO 4mA, even in datasheet it is 700uA

Embel_Tech — Mon, 16 Jan 2023 13:18:33 GMT

yes.

there is no delay function in code for current measuring .I already removed from code.

RE: ADC CURRENT CONSUMPTION IS 3 TO 4mA, even in datasheet it is 700uA

Jared — Wed, 11 Jan 2023 15:34:13 GMT

Hi,

I measured about 700 µA with the hex that you shared. Did you remove the delay before sending me the hex? 3-4 mA is expected if nrf_delay_ms(5000) is used because the CPU will just spin in a loop for 5 seconds.

regards

Jared

RE: ADC CURRENT CONSUMPTION IS 3 TO 4mA, even in datasheet it is 700uA

Embel_Tech — Fri, 06 Jan 2023 12:49:08 GMT

devzone.nordicsemi.com/.../saadc_5F00_lowpower.hex

I have attached hex file for your reference. Please check it.

RE: ADC CURRENT CONSUMPTION IS 3 TO 4mA, even in datasheet it is 700uA

Embel_Tech — Thu, 05 Jan 2023 09:02:56 GMT

Actually power profiler is not with us.so we are measuring current through multimeter itself.

RE: ADC CURRENT CONSUMPTION IS 3 TO 4mA, even in datasheet it is 700uA

Jared — Thu, 05 Jan 2023 08:16:53 GMT

Hi,

Why would you need to add the delay to measure the current? What does the current change to if you remove the delay?

Can you share a pre compiled hex that I can flash to my nRF52 development kit so I can verify the measurement.

regards
Jared

RE: ADC CURRENT CONSUMPTION IS 3 TO 4mA, even in datasheet it is 700uA

Embel_Tech — Thu, 05 Jan 2023 05:43:20 GMT

YES.

As i am measuring current by multimeter with below function, delay is added here to capture current value on multimeter.

saadc_init(); // SAR adc initialisation_Channel 0_12bit resolution_VDD as input.
nrf_saadc_value_t adc_val;
nrfx_saadc_sample_convert(0,&adc_val);
nrf_delay_ms(5000); // added for current measurement
nrfx_saadc_uninit();

I also tried nrfx_saadc_abort(), and wait for NRFX_SAADC_EVT_DONE .

but getting same current about 3- 4mA.

RE: ADC CURRENT CONSUMPTION IS 3 TO 4mA, even in datasheet it is 700uA

Jared — Wed, 04 Jan 2023 15:10:30 GMT

Hi there,

How are you measuring the current?

Can you try to call nrfx_saadc_abort(), and wait for NRFX_SAADC_EVT_DONE event before you call nrfx_saadc_uninit()?

regards

Jared