Source code to achieve 1.5uA standby current

[Sridhar Jonnavittula]

Hi all,

I wanted to see this below screen shot current number on nRF52840 DK

For that I changed peripheral/blinky example main() like this but I am seeing 14uA.

/* Configure board. */
//bsp_board_init(BSP_INIT_LEDS);

NRF_POWER->RAM[0].POWERCLR = 0xFFFF;
NRF_POWER->RAM[1].POWERCLR = 0xFFFF;
NRF_POWER->RAM[2].POWERCLR = 0xFFFF;
NRF_POWER->RAM[3].POWERCLR = 0xFFFF;
NRF_POWER->RAM[4].POWERCLR = 0xFFFF;
NRF_POWER->RAM[5].POWERCLR = 0xFFFF;
NRF_POWER->RAM[6].POWERCLR = 0xFFFF;
NRF_POWER->RAM[7].POWERCLR = 0xFFFF;
NRF_POWER->RAM[8].POWERCLR = 0xFFFF;

/* Toggle LEDs. */
while (true)
{
__WFE();
#if 0
for (int i = 0; i < LEDS_NUMBER; i++)
{
bsp_board_led_invert(i);
nrf_delay_ms(500);
}
#endif
}

Can anyone please provide me the source code to achieve that 1.5uA number?

Thanks

Sridhar

[Simonr]

1. No, I also see ~3µA using the PPK. This is likely due to leakage currents on the DK, and if you measure this as an external board, using the nRF Only setting and the debugger of another DK you should be able to see ~1.5µA. You can see how to do this in the PPK user guide.

2. This seems somewhat unrelated to this ticket's topic, so please create a new ticket regarding this issue. We strive to keep each ticket to one topic, to keep it easier for future customers with similar issues to search for one specific topic.

Best regards,

Simon

[Sridhar Jonnavittula]

#include "nrf.h"
#include "nrf_gpio.h"
#include "nrf_drv_rtc.h"
#include "nrf_drv_clock.h"
#include "boards.h"
#include "app_error.h"
#include "nrf_delay.h"
#include <stdint.h>
#include <stdbool.h>

#define COMPARE_COUNTERTIME  (3UL)                                        /**< Get Compare event COMPARE_TIME seconds after the counter starts from 0. */

#ifdef BSP_LED_0
    #define TICK_EVENT_OUTPUT     BSP_LED_0                                 /**< Pin number for indicating tick event. */
#endif
#ifndef TICK_EVENT_OUTPUT
    #error "Please indicate output pin"
#endif
#ifdef BSP_LED_1
    #define COMPARE_EVENT_OUTPUT   BSP_LED_1                                /**< Pin number for indicating compare event. */
#endif
#ifndef COMPARE_EVENT_OUTPUT
    #error "Please indicate output pin"
#endif

const nrf_drv_rtc_t rtc = NRF_DRV_RTC_INSTANCE(0); /**< Declaring an instance of nrf_drv_rtc for RTC0. */

/** @brief: Function for handling the RTC0 interrupts.
 * Triggered on TICK and COMPARE0 match.
 */
static void rtc_handler(nrf_drv_rtc_int_type_t int_type)
{
    if (int_type == NRF_DRV_RTC_INT_COMPARE0)
    {
       // nrf_gpio_pin_toggle(COMPARE_EVENT_OUTPUT);
    }
    else if (int_type == NRF_DRV_RTC_INT_TICK)
    {
        //nrf_gpio_pin_toggle(TICK_EVENT_OUTPUT);
    }
}

/** @brief Function configuring gpio for pin toggling.
 */
static void leds_config(void)
{
    bsp_board_init(BSP_INIT_LEDS);
}

/** @brief Function starting the internal LFCLK XTAL oscillator.
 */
static void lfclk_config(void)
{
    ret_code_t err_code = nrf_drv_clock_init();
    APP_ERROR_CHECK(err_code);

    nrf_drv_clock_lfclk_request(NULL);
}

/** @brief Function initialization and configuration of RTC driver instance.
 */
static void rtc_config(void)
{
    uint32_t err_code;

    //Initialize RTC instance
    nrf_drv_rtc_config_t config = NRF_DRV_RTC_DEFAULT_CONFIG;
    config.prescaler = 4095;
    err_code = nrf_drv_rtc_init(&rtc, &config, rtc_handler);
    APP_ERROR_CHECK(err_code);

    //Enable tick event & interrupt
    //nrf_drv_rtc_tick_enable(&rtc,true);

    //Set compare channel to trigger interrupt after COMPARE_COUNTERTIME seconds
    //err_code = nrf_drv_rtc_cc_set(&rtc,0,COMPARE_COUNTERTIME * 8,true);
    //APP_ERROR_CHECK(err_code);

    //Power on RTC instance
    nrf_drv_rtc_enable(&rtc);
}

/**
 * @brief Function for application main entry.
 */
int main(void)
{
    leds_config();

    lfclk_config();

    rtc_config();

#if 0
//NRF_POWER->RAM[0].POWERCLR = 0xFFFF;
NRF_POWER->RAM[1].POWERCLR = 0xFFFF;
NRF_POWER->RAM[2].POWERCLR = 0xFFFF;
NRF_POWER->RAM[3].POWERCLR = 0xFFFF;
NRF_POWER->RAM[4].POWERCLR = 0xFFFF;
NRF_POWER->RAM[5].POWERCLR = 0xFFFF;
NRF_POWER->RAM[6].POWERCLR = 0xFFFF;
NRF_POWER->RAM[7].POWERCLR = 0xFFFF;
//NRF_POWER->RAM[8].POWERCLR = 0xFFFF;
#endif

    while (true)
    {
        __SEV();
        __WFE();
        __WFE();
    }
}


/**  @} */
#endif

I have modified RTC example as above. I get 54uA average for 1.5ms for every 20ms time. I did not change the LF clock source which is by default crystal. 

May I know why it is consuming?

Thanks

[Simonr]

I think the current consumption should go down if you do clear the RAM blocks in your main loop, I.E. setting #if 1 and not 0 in your main loop.

Best regards,

Simon