Interruption when USB is connected

[backstreet.devisor]

Hi.

Could you please tell me how to trigger an interrupt when changing the USBREGSTATUS register?

I can monitor the state of this register in polling mode, but I don't know how to trigger an interrupt when it changes. Could you please provide a code example how to do it rationally with minimal memory usage of the microcontroller?

Thanks.

[Håkon Alseth]

Hi,

 

You can use the usb_enable function to provide a callback that gives such information:

 RE: nRF52820 USB connection detection 

Here's an example implementation:

https://github.com/nrfconnect/sdk-nrf/blob/v2.7.0/applications/connectivity_bridge/src/modules/usb_cdc_handler.c#L239

https://github.com/nrfconnect/sdk-nrf/blob/v2.7.0/applications/connectivity_bridge/src/modules/usb_cdc_handler.c#L148

 

Kind regards,

Håkon

[backstreet.devisor]

Hi Hakon. Thank you for your response with an example.

But I am not yet able to implement this function in my application. I'm getting errors that I can't fix.

Here's my code -->

#include <stdio.h>
#include <zephyr/kernel.h>
#include <zephyr/drivers/gpio.h>
#include <zephyr/usb/usb_device.h>

#include <zephyr/logging/log.h>
LOG_MODULE_REGISTER(v52820, LOG_LEVEL_DBG);

static void usbd_status(enum usb_dc_status_code cb_status, const uint8_t *param)
{
	switch (cb_status) {
	case USB_DC_CONNECTED:
		LOG_DBG("USB_DC_CONNECTED");
		break;
	case USB_DC_DISCONNECTED:
		LOG_DBG("USB_DC_DISCONNECTED");
		break;
	default:
		break;
	}
}

int main(void)
{
	int err;

	err = usb_enable(usbd_status);
	if (err) {
		LOG_ERR("usb_enable: %d", err);
		return false;
	}

	while (1){
	
		k_msleep(1000);			
	}

	return 0;
}

prj.conf file -->

CONFIG_GPIO=y
CONFIG_LOG=y
CONFIG_USB_DEVICE_STACK=y

Here are the errors I see while building the project -->

...

Can you please tell me where I'm making a mistake?

Does the prj.conf file need to include anything else besides CONFIG_USB_DEVICE_STACK?

Thanks.

[Håkon Alseth]

Hi,

 

I added your prj.conf and src to hello_world, and compiled for board nrf52833dk_nrf52820 without seeing any compiler problems.

Could you share more information about your build, ie. which board and ncs version that you are using?

 

Can you for instance build zephyr/samples/subsys/usb/hid without problems?

 

Kind regards,

Håkon

[backstreet.devisor]

Hi.

I am using a custom board based on the nRF52820.
SDK v.2.7.0
Toolchain v.2.7.0

When building the HID project, I also see errors -->

[Håkon Alseth]

Try to add this to your board:

https://github.com/nrfconnect/sdk-zephyr/blob/v3.6.99-ncs2/boards/nordic/nrf52833dk/nrf52833dk_nrf52820.dts#L176-L179

 

And remove the build folder and regenerate the project.

 

Kind regards,

Håkon

[backstreet.devisor]

Yeah, that helped. Thank you so much for your help.

However, such a solution is memory resource intensive, in particular RAM memory (assuming I don't need to transfer any data over USB, I just need to detect when the charger is connected to the board). 

Is it possible to solve this problem by directly accessing registers?

Would such a solution be more economical in terms of RAM memory?

[Håkon Alseth]

Hi,

 

You can use NRFX_POWER for this purpose, this can give you the power events that you're after with little overhead in terms of RAM/flash usage.

 

Kind regards,

Håkon