Delay Init wifi on nrf5340 and nrf7002

RE: Delay Init wifi on nrf5340 and nrf7002

Håkon Alseth — Thu, 31 Jul 2025 11:46:54 GMT

Hi,

Instead of setting up a SYS_INIT() function, you should use regulators-fixed instead:

https://github.com/zephyrproject-rtos/zephyr//blob/main/boards/nordic/thingy53/thingy53_nrf5340_common.dtsi#L117-L122

You can set a delay on the boot-up with this as well:

https://github.com/zephyrproject-rtos/zephyr//blob/v4.0-branch/boards/seeed/xiao_ble/xiao_ble_nrf52840_sense.dts#L27

Please note that you should have a 6 ms delay after supplying a valid VBAT, as described here:

https://docs.nordicsemi.com/bundle/ps_nrf7002/page/chapters/hw_layout/doc/hw_layout.html#ariaid-title13

Kind regards,

Håkon

RE: Delay Init wifi on nrf5340 and nrf7002

TeoJordaan — Wed, 30 Jul 2025 10:02:08 GMT

Hi Hakon,

Q1 Answer: It is a custom design that hasn't been reviewed.

Q2 Answer: I am using my own custom board dts, so the forwarder is not included (hasn't been enabled or disabled)

Q3 Answer:

I need to answer the question in 2 cases.

Case 1 (Permanent supply to the nRF7002):

Everything works fine and i can connect to a Wi-Fi network.

Case 2 (Supply to nRF7002 switched on during device initialization):

Wi-Fi stack fails as it attempts to communicate with the nRF7002 before it has been powered on. As far as i can tell, once this has failed there is no function call to restart the stack / driver.

For a bit more background info, we are intending to use this for a low power field telemetry device. The sleep current needs to be around 40uA. The nRF7002 sleep current is 1.8mA unless TWT is used (as far as I can tell); however i cant assume that all our customers routers are Wi-Fi 6; therefore TWT is not a complete solution. That is why i want to completely disconnect supply from the nRF7002 when i go to sleep.

I am in the process of trying the following to solve both cases:

1. Initialize the en3v4 (provide power to the nRF7002) before the kernel is initialized:

//Initialize 3V4 as on by default so wifi stack works
static int early_gpio_init(void)
{
    nrf_gpio_cfg_output(DT_GPIO_PIN(DT_NODELABEL(qen3v4), gpios));
    nrf_gpio_pin_set(DT_GPIO_PIN(DT_NODELABEL(qen3v4), gpios));
    //Delay for 500us so 3V4 settles
    for(volatile uint32_t i = 0; i<32000; i++){
        __asm__ volatile("nop");
    }
    return 0;
}
//Initialize funtion to be executed before the kernel initializes
SYS_INIT(early_gpio_init, PRE_KERNEL_1, 0);

2. Before sleeping, disconnect Wi-Fi, drop Wi-Fi interface with

net_if_down(netIF);

3. Switch off supply to the nRF7002 and then sleep

4. Wake from sleep and witch on supply to the nRF7002

4. Raise wifi interface with:

net_if_up(netIF);

Do you think that this approach would work?

RE: Delay Init wifi on nrf5340 and nrf7002

Håkon Alseth — Wed, 30 Jul 2025 08:33:32 GMT

Hi,

It seems that there is an issue to initialize the nrf7002 on your design. This can be due to many factors, but it usually is some sort of connection issue or pin conflict.

Q1: If this is a custom design, have you had it reviewed by us on a previous occasion?

Q2: By default, pins P1.00-P1.05 are forwarded to the network core for uart prints. You seem to use P1.05 as the host irq.

Have you ensured that the gpio-forwarder is disabled?

This is done by adding this to your overlay:

&gpio_fwd {
	status = "disabled";
};

Q3: Do all nrf/samples/wifi examples behave like this?

Kind regards,

Håkon