Hi @andrealongobardi ,
To this method, normally have these way:
1. in your app, jump to the flashloader code, as the flashloader code can support the USB serial download.
Normally, let the flashloader code story in the RAM, then jump to the flashloader, you can refer to this post:
https://www.nxpic.org.cn/module/forum/thread-620172-1-1.html
2. Use secondary bootloader
After boot, it will stay in the serail download mode, can use the blhost do the USB HID connect the board, do the code downloading, or wait after the timeout and jump to your real app.
You can refer to our SBL and SFW, that already support it.
https://github.com/nxp-mcuxpresso/sbl
https://github.com/nxp-mcuxpresso/sfw
This is the document:
https://www.nxp.com/docs/en/user-guide/MCUOTASBLSFWUG.pdf
Wish it helps you!
If you still have questions about it, please kindly let me know.
Best Regards,
Kerry
