BLE NUS central + USB (usb not enabled on power detection)

[Julian]

Hi all,

I'm trying to combine the BLE NUS central with USB CDC functionality.

I have copied over functions from the USB CDC ACM example into the BLE_APP_UART central example. 

I have enabled all the relevant USB modules in sdk_config.h

Upon flashing, the BLE NUS central functions work well. However as soon as I connect the nRF USB, the program hangs immediately.

I discovered that this issue is due to the USB peripheral waiting to be enabled upon receiving the power detection event.

This is the loop below.

while (0 == (NRF_USBD_EVENTCAUSE_READY_MASK & nrf_usbd_eventcause_get()))
{
/* Empty loop */
}

So it seems that EVENTCAUSE is always 0 and the loop never ends.

I'm using SES with SDK15, which already has the errata fixes implemented, so I'm quite unsure why this issue still persists.

However, I found out that I can make my code work by first flashing the usb_cdc_acm example, then flashing my actual modified code.

It works until I reflash it again. Then I would need to repeat the procedure.

I'm testing this using a custom PCB with the rev1 QIAA-C0 variant, as I have a non-working USB V0.92 PCA10056.

Any help appreciated. I can provide the SES project file if needed.

[Håkon Alseth]

Hi,

 

Unfortunately, we have a known issue with SDK v15, where the USBD erratas is not properly applied for the latest chip revision. Could you try the workaround posted here and see if this works?

https://devzone.nordicsemi.com/f/nordic-q-a/34605/usb-not-enumerating-after-reset/133051#133051

 

Kind regards,

Håkon

[Julian]

Just applied the workaround posted. It now works reliably.

Thanks!

[Julian]

Hi Håkon, I may have spoken too soon.

Upon further testing, it seems that the USB only enumerates when it is running in debug mode (I'm using SES).

It doesn't enumerate if I run it normally, or after power cycle from a debug session.

[Håkon Alseth]

Sounds like you're seeing the same issue as this thread: https://devzone.nordicsemi.com/f/nordic-q-a/37477/unable-to-run-uart-ble-app-example-without-debugger

Could you try the workarounds posted there?

[Julian]

Hi,

I did face that issue described in the link as I was previously using SES v3.40. Now I have downgraded to SES 3.34b, and no longer facing compile problems due to the _putchar() function.

However the issue still persists, and only happens when I include USB functionalities in the code. I am also running an NFC launch app function, and what's weird is that the NFC works on power up(without having to run in debug), which tells me that the code is running, but the USB fails to enumerate. It only enumerates if I force to run in debug, which might or might not be related to the issue in the link.

I will try out the workaround in the link which is intended for SES v3.40, and let you know of my result.

Thanks for your support!