nRFSDK 17.1.0 Serial DFU Not Reliable

[WestCoastDaz]

I am working on a project that requires serial DFU without flow control using nRF SDK 17.1.0 running on the nRF52840 without the soft device as I don't need BLE for this application.

I am unable to get the bootloader to update reliably using `nrfutil` v6.1.3 on any OS (MacOS or Windows).  The length check fails on line 139 of `nrf_fstorage_write` after a ~10 packets have been sent down to the device.  I have tried lowering the baud rate all the way down to 2,400 at which point I got it to work 3 times in a row but now it keeps failing.

I have seen serval posts stating that the serial DFU works without flow control but at lower baud rates (somewhere around 38400) but 2400 seems very low.  How best can I solve this issue?

Thanks, 

[Vidar Berg]

Hello,

I was not able to reproduce this here on a 52840DK. I used the original debug uart bootloader, disabled flow control, and changed the baud rate to 38400. Please try to disable the USB Mass storage class on the Jlink if you are using it as the serial bridge to your PC/Mac: https://developer.nordicsemi.com/nRF_Connect_SDK/doc/latest/zephyr/guides/tools/nordic_segger.html#disabling-the-mass-storage-device-functionality. Although not as common, I have seen this Jlink issue cause problems on some Windows setups as well.   You can also try to see if a lower '-prn, --packet-receipt-notification' value improves the reliability when you run nrfutil.

Best regards,

Vidar

[WestCoastDaz]

Vidar Berg

Thank you for the suggestions.  I had already disabled the mass storage device on the dev kit to see if it would help but it didn't.  We aren't using the DK interface micro for this test, we are using RPI connected directly to dev kit headers.

In the end our testing should that setting the `-t` argument to 2 resolved the issue.

Thanks,