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. The VIN 3-5 pin on P20 is not connected to VDDH, just the internal 5V regulator, so it will only power the nRF in VDD mode. I asked a developer for confirmation, and the only ways to run the nRF52840 in VDDH mode on the DK are USB (J3) and through the Li-Po battery connectors (J6 or P27).

2. Correct, the PPK is not intended to use to measure chips in VDDH mode, so you should rather use an oscilloscope or power analyzer.

Best regards,

Simon

[Sridhar Jonnavittula]

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/** @file
 * @defgroup rtc_example_main main.c
 * @{
 * @ingroup rtc_example
 * @brief Real Time Counter Example Application main file.
 *
 * This file contains the source code for a sample application using the Real Time Counter (RTC).
 *
 */

#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 1
//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();
    }
}


/**  @} */

I have modified the RTC example in SDK_16.0/examples/hardware_peripherals/rtc. In sdk_config.h kept LFCLK source as RC oscillator. I have commented RTC TICK events, LEDs. I have powered off all RAM banks except 0 and 8. I see 60uA current continuously other than COMPARE event.

Can you please suggest why I am seeing that much current? I have to see 1.5uA as in the first query.

Thanks