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,

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 

[Kazi Afroza Sultana]

Hello Ian,

DC DC enabled generally should not be the cause of higher current consumption. Correct DC DC can ensure lower current consumption. 

It would be helpful if you can share your schematic so I can see how VDD is routed on the custom board and if the DCDC components (LC filter) is correctly populated according to our schematic. 

I also need to check the pinctrl.dtsi file from board file.

[Ian Daintith]

Hi Kazi

We waited 6 days for this reply and you kindly went on to explain about DCDC.

You missed the point where I said we are NOT using DCDC.  

So we have simple code running at a DK that take 2uAmps, run it on our depopulated custom PCB and it take 740uAmps. So I look at the differences. 

1. DK uses DCDC. Our PCB does not. 

2. Our PCB has VDDH and VDD tied together the DK does not. 

I have shared the DTS and DTSI with you at the start of this ticket 2 weeks ago. 

I cannot share the schematic on a public forum but happy to send to you privately if you can advise on how to do that. 

So the question still stands - what could cause the consumption to be in the order of 740uAmps for such simple code on a depopulated custom PCB?

Regards

Ian

[Ian Daintith]

We verified low power on our depopulated board.