nRF52840DK+nRF7002EK, cannot enter low power unless build without nRF7002

RE: nRF52840DK+nRF7002EK, cannot enter low power unless build without nRF7002

esmart-engineering — Wed, 06 Aug 2025 16:57:48 GMT

Yes, looks like the interface MCU was drawing that extra current. I adjusted SW6 and was able to lower it to around 400uA. Thank you.

RE: nRF52840DK+nRF7002EK, cannot enter low power unless build without nRF7002

Simonr — Tue, 05 Aug 2025 11:09:46 GMT

Please check out the nRF7002 DK HW user guide here, that explains how you should do current consumption measurements on the nRF7002 DK: https://docs.nordicsemi.com/bundle/ug_nrf7002_dk/page/UG/nrf7002_DK/nRF5340_nRF7002_measure_current.html

I'm suspecting that you're seeing the current consumption of the entire nRF7002 DK, interface MCU and all.

Best regards,

Simon

RE: nRF52840DK+nRF7002EK, cannot enter low power unless build without nRF7002

esmart-engineering — Tue, 05 Aug 2025 00:26:41 GMT

Hello again. We got a hold of the nRF7002DK and tried testing it, but still was not able to see the current consumption go down i.e., it still stays around 12mA being drawn from external power supply and there still seems to be leakage from IOVDD net.

I did the following:

Grabbed NCS v3.0.2 (the version that the erratum states should have fixed this)
Made a project based off WiFi station (nrf/samples/wifi/sta) using that SDK version
Set up the build config to build it for 'nrf7002dk/nrf5340/cpuapp' and use 'prj.conf'
Added the sys_poweroff() call, like I did with the nRF52DK (zephyr/samples/boards/nordic/system_off)
Added code to shut down the nRF7002 (nrf/samples/wifi/shutdown)
Used external power supply with 3.5V at P21
- SW10 is also switched to the 'Li-Poly' side, and I'm sure the voltage was not applied in reverse
- Note that I'm not using AA batteries at this time

Summary of the code:

/**** main.c ****/

// ...

static int wifi_shutdown(void)
{
	int ret;
	struct net_if *iface = net_if_get_default();

	if (!net_if_is_admin_up(iface)) {
		return 0;
	}

	ret = net_if_down(iface);
	if (ret) {
		LOG_ERR("Cannot bring down iface (%d)", ret);
		return ret;
	}

	LOG_INF("Interface down");

	return 0;
}

// ...

int main(void)
{
	int ret = 0;

	net_mgmt_callback_init();

	wifi_shutdown();
	k_sleep(K_SECONDS(3));

	sys_poweroff();
}

Hardware setup:

(picture will be uploaded soon; DevZone is having errors uploading files)

Power supply from red/blue clips at the top
PPK2 acting as ammeter and in series with power supply
nRF7002DK's P21 (+) connecting to PPK2's VOUT
nRF7002DK's SW10 at 'Li-Poly' side

RE: nRF52840DK+nRF7002EK, cannot enter low power unless build without nRF7002

esmart-engineering — Tue, 29 Jul 2025 20:25:41 GMT

Thank you for your reply Simon. This does seems to be the root cause; we verified this by trying to remove the nRF7002EK after sleeping and noticed a current draw lowered back to the uA range.

We've started to work on getting the DK and will continue testing again once we have it. Thank you again for the detailed answer and suggestion.

RE: nRF52840DK+nRF7002EK, cannot enter low power unless build without nRF7002

Simonr — Tue, 29 Jul 2025 08:06:35 GMT

I think this could be due to erratum 9 of the nRF7002. With higher IOVDD voltages, pins that are not in use and configured to floating (like they are generally on the nRF7002 EK), there will be leakage currents. This unfortunately means that the nRF7002 EK isn't very well suited for current consumption measurements since the pin configuration doesn't match the workaround for this errata. The DK or a custom board should be better suited for current consumption. Lowering the supply voltage should lower the current consumption considerably as well.

Best regards,

Simon

RE: nRF52840DK+nRF7002EK, cannot enter low power unless build without nRF7002

esmart-engineering — Fri, 25 Jul 2025 21:24:26 GMT

Simonr We have been using nRF chips for 10+ years and we have successfully launched multiple projects w/ nRF52, nRF53, nRF7002. Please do not just reply w/ generic answer, which we have ALREADY looked at BEFORE responding.

Please do not just reply for "reply sake". Need concrete useful answer, please

RE: nRF52840DK+nRF7002EK, cannot enter low power unless build without nRF7002

esmart-engineering — Fri, 25 Jul 2025 17:03:26 GMT

I've already tried most of these: CONFIG_PM=y and CONFIG_SERIAL=n (as mentioned in the original post), disabling several peripherals, CONFIG_NRF_WIFI_LOW_POWER=y, etc. but it did not dramatically cut back on the power draw. I also found this regarding nRF7002 in low power, and tried net_mgmt() with NET_REQUEST_WIFI_PS (as seen in NCS v2.9.1, nrf/samples/wifi/provisioning/softap) but it did not seem to have effect.

Do also note that if the PPK2 is placed on nRF52840DK P22 (instead of at my 3.3V supply), it reports about 600uA. Again, I've already changed SW6 to be "nRF Only". So I'm not sure what could be drawing the extra 11.4mA.

With my method of disconnecting power to nRF7002 when measuring current, wouldn't the nRF7002 (including the WiFi radio) be naturally turned off?

Is there a way in firmware to disable the SPI peripheral being used for communication between the two nRF's?

RE: nRF52840DK+nRF7002EK, cannot enter low power unless build without nRF7002

Simonr — Fri, 25 Jul 2025 10:51:12 GMT

Please follow the power optimization recommendations we have here. That should cover both general recommendations and the specific Wi-Fi power save mode available here: https://docs.nordicsemi.com/bundle/ncs-latest/page/nrf/test_and_optimize/optimizing/power_general.html#general-recommendations

A power consumption below 10µA should definitely be doable if both the nRF7002 and nRF52840 are in sleep mode and there are no other things drawing power. Note that 12mA is very much, and only sounds like a leakage current or the Wi-Fi radio being on.

Best regards,

Simon