Cannot achieve low-power on nRF52833 custom PCB using simplest main() yields 740uAmps

[Ian Daintith]

Chip : nRF52833 QIAA

Environment : Visual Code + nRF Connect for VC Code V2025.8.654 NCS V3.1.0

I am hoping somebody could assist us with a problem we are having achieving the expected low current operation on the nRF52833 soc on a custom PCB in sys_poweroff()  (and also in k_sleep())

In an attempt to narrow this down have depopulated the PCB to contain just the nRF52833 SOC all the other passives and bus peripherals are de-soldered. 

I have created a simple application which does nothing other than to set all GPIO as inputs and enter k_sleep () and the current is measured using PPK2 at ~750uAmps. There is spiking activity 

It feels like I have read every article on this subject from here and the suggested sample such as \ncs\v3.1.0\zephyr\samples\boards\nordic\system_off.   Please can anyone suggest a remedy?

main.c

#include <zephyr/kernel.h>
#include <zephyr/drivers/hwinfo.h>
#include <zephyr/sys/poweroff.h>
#include <hal/nrf_gpio.h>

int main(void)
{
    for (uint8_t idx = 0; idx < NUMBER_OF_PINS; idx++)
    {
        nrf_gpio_cfg_default(idx); // Input, no pull up/down, no sense
    }

    // k_sleep(K_FOREVER);
    hwinfo_clear_reset_cause();
    sys_poweroff();

    return 0;
}

prj.conf

#Debug support
CONFIG_USB_DEVICE_STACK=n
CONFIG_BOOT_BANNER=n
CONFIG_PRINTK=n
CONFIG_SERIAL=n
CONFIG_CONSOLE=n
CONFIG_UART_CONSOLE=n
CONFIG_LOG=n
CONFIG_DEBUG_OPTIMIZATIONS=n
CONFIG_DEBUG_THREAD_INFO=n


CONFIG_POWEROFF=y
CONFIG_PM_DEVICE=y
CONFIG_PM_DEVICE_RUNTIME=y
CONFIG_MULTITHREADING=y

CONFIG_GPIO=y
CONFIG_HWINFO=y

I have created a DTS, DTSI, Def Config as attached. (No UARTs enabled, No SPI enabled, No I2C enabled, No Temp controller enabled, No RNG enabled , No external flash etc). No logging, no prink etc. 

/dts-v1/;
#include <nordic/nrf52833_qiaa.dtsi>
#include "X30_bare-pinctrl.dtsi"
#include <zephyr/dt-bindings/input/input-event-codes.h>

/ {
	model = "Bare X30";
	compatible = "Extronics,X30-bare";

	chosen {
		zephyr,sram = &sram0;
		zephyr,flash = &flash0;
		zephyr,code-partition = &slot0_partition;
	};

	
	};

&uicr {
	nfct-pins-as-gpios;
};

&gpiote {
	status = "okay";
};

&gpio0 {
	status = "okay";
};

&gpio1 {
	status = "okay";
};

&flash0 {
	partitions {
		compatible = "fixed-partitions";
		#address-cells = <1>;
		#size-cells = <1>;

		boot_partition: partition@0 {
			label = "mcuboot";
			reg = <0x00000000 DT_SIZE_K(48)>;
		};

		slot0_partition: partition@c000 {
			label = "image-0";
			reg = <0x0000c000 DT_SIZE_K(220)>;
		};

		slot1_partition: partition@43000 {
			label = "image-1";
			reg = <0x00043000 DT_SIZE_K(220)>;
		};

		storage_partition: partition@7a000 {
			label = "storage";
			reg = <0x0007a000 DT_SIZE_K(24)>;
		};
	};
};

&uart0 {
	status = "disabled";
};

&uart1 {
	status = "disabled";
};


&spi0 {
	compatible = "nordic,nrf-spi";
	status = "disabled";
};

&spi1 {
	compatible = "nordic,nrf-spi";
	status = "disabled";
};

&spi2 {
	compatible = "nordic,nrf-spi";
	status = "disabled";
};

&i2c0 {
	compatible = "nordic,nrf-twim";
	status = "disabled";
};

&i2c1 {
	compatible = "nordic,nrf-twim";
	status = "disabled";
};

&i2c1 {
	compatible = "nordic,nrf-twim";
	status = "disabled";
};

&temp {
	status = "disabled";
};

&rng {
	status = "disabled";
};

&rng_hci {
	status = "disabled";
};

&adc {
	status = "disabled";
};

&wdt0 {
	status = "disabled";
};

The build files 

build-folder/zephyr/zephyr.dts
build-folder/zephyr/.config  (.txt to enable attachment)

are attached. 

Fullscreen 5736.X30_bare_defconfig.txt Download

CONFIG_ARM_MPU=y
CONFIG_HW_STACK_PROTECTION=y

# enable GPIO
CONFIG_GPIO=y

7802.X30_bare.dts1526.X30_bare-pinctrl.dtsi

[Kazi Afroza Sultana]

Hello,

Did you try the sample with the nRF52833 DK and check if you can get the current in range?

I can see that you disabled almost all unused peripheral in the overlay. However, to make it sure I would like to suggest you run only a minimal sample without for loop part. for example:

void main(void)
{
    // Minimal init only
    k_sleep(K_FOREVER);
    // or: sys_poweroff();
}

If the current consumption still not in specified range, then we can say there are other peripheral still enabled or some issue on the board.

Try this first and let me know the outcome.

Thanks.

BR

Kazi

[Ian Daintith]

Hi Kazi, thank your reply. We will test this as you suggest on Monday 1 Dec and report the results. 

[Ian Daintith]

Hello Kazi

We repeated the tests on 3 x nRF 52833 DK using the Nordic procedure defined here https://docs.nordicsemi.com/bundle/ug_nrf52833_dk/page/UG/dk/hw_measure_current.html. Using the PPK2 as source meter. 

DK1 - 8uAmps

DK2 - 8uAmps

DK3 - ~600uAmps

The boards appear identical to us in configuration. All 3 flashed from Visual Code NCS Extension SDK v3.1.0. 

We cannot explain the difference on DK3. Do you have any ideas please?

DK1  showing 8.34uA 

DK3 Showing ~ 600uAmps. - SAME CODE!

Board set up

[Kazi Afroza Sultana]

Hello,

For measuring current using source meter, the VOUT pin of PPK will be connected to VDD pin of nRF current measurement header and GND will be connected to minus pin of external supply.

I can see you have connected to VOUT to the external supply. 

[Ian Daintith]

Thank you Kazi. Yes I have since managed to measure the current on the nrf52833 DK correctly at ~2uAmp. ( see here. Definitive guide on measuring current using PPK2 + nRF 52833 DK )

So we have a situation where this simple code below takes

2uAmp on nRF 52833 DK

740Amps on custom depopulated PCB. 

I have shared the DTS and DTSI with you. 

One key difference I can see with the DK is that we are not using DCDC. 

We do not understand what could still be running on the nRF 52833.

Thank you 

Ian