USB DFU

RE: USB DFU

leehaney — Tue, 24 Feb 2026 04:29:10 GMT

If you’re using an nRF52840 over a virtual COM port, the issue is likely not Qt but the DFU protocol itself.

A few things to check:

Make sure the nRF52840 is actually in DFU mode, not normal application mode.
Verify baud rate, parity, stop bits, and flow control match the device settings.
Confirm that 0x06, 0x01, 0x0C is valid for the specific DFU protocol you’re using (Nordic Secure DFU is packet-based and not simple raw commands).
Check whether the device expects SLIP encoding or a specific packet structure (init packet + CRC).
Use a serial sniffer or log the raw TX/RX data to confirm the device is receiving the bytes. eggy car

If this is Nordic Secure DFU, you cannot just send raw hex commands — the packets must follow the DFU transport protocol.

RE: USB DFU

shsh — Mon, 30 Dec 2024 09:24:27 GMT

Thank you, I have solved this problem, I run on win64, send command does not reply the first reason is that QT5 comes with the library QSerialPort has a problem, but I do not know where the problem is, I now replace the open-source qextserialport on github to solve it. 52840 cannot receive after sending. The second problem is to send the ending 0XC0 which I wrote 0X0C

RE: USB DFU

Sigurd Hellesvik — Mon, 30 Dec 2024 07:20:26 GMT

Which device does the above qt C++ code run on?

RE: USB DFU

shsh — Mon, 30 Dec 2024 00:28:56 GMT

I am using SDK 17.0.2, I am using either homemade DFU or USB-Secure, I am using 52840, if I use nrfutil I can download the program, I would like to refactor nrfutil, thank you

RE: USB DFU

Sigurd Hellesvik — Fri, 27 Dec 2024 07:45:32 GMT

Hi,

For us to help you with this in the best possible way, please list the following information:

SDK Version
Which sample do you use, if any?
Do you use custom hardware or code?

Regards,
Sigurd Hellesvik