LPC55S16: Signed image with USB CDC implementation not working

[VChaudhary]

Hi,

I have created an application that initializes the USB1 as a CDC ACM device. The application works fine when I load the unsigned image. The USB gets recognized on my PC. But When I load a signed image using the secure boot option and reset the board. It stops recognizing. Please see the attached error screenshot from my PC.

using blhost for loading the image and elftosb-gui for signing the image. and following "AN12283
LPC55Sxx Secure Boot" document for signing the image and enabling the secure boot.

Please help!!

Thanks

[VChaudhary]

Update:

1. If I use freertos examples and flash plain and signed image through the MCUxpressProvisioning tool. The image doesn't work.

2. If I use normal examples which do not include freertos and flashes through the MCUxpressProvisioning tool, both plain and signed images works.

So the issue is with the applications which use freertos.

[xiangjun_rong]

Hi,

I suggest you use the tools MCUXPRESSO-SECURE-PROVISIONING to sign your *.bin file, the an12283.pdf uses independent script to sign a file, it is a bit complex. The tools is an IDE user interface, it can compute the RSA private/public keys and generate X.509 certificate automatically.

Pls download the MCUXPRESSO-SECURE-PROVISIONING tools from the link, it supports LPC55xx family.

https://www.nxp.com/design/software/development-software/mcuxpresso-software-and-tools-/mcuxpresso-s...

Hope it can help you

BR

XiangJun Rong

[VChaudhary]

Hi @xiangjun_rong 

Thanks for your reply!!

I tried with MCUXpresso Provisioning Tool also, below are the observations.

1. Generated .bin file from MCUXpresso IDE using Create Binary Utility.
2. Flashed the generated binary using blhost. USB works fine.
3. Used MCUXpresso Provisioning Tool, and Built the image (Boot Selected as Plain), and when writing used Built image from bootable_images folder. USB doesn't work.
4. Used MCUXpresso Provisioning Tool, and Built the image (Boot Selected as Plain), and when writing used source image from source_images folder, not from bootable_images folder. USB works fine.

5. Selected Boot as signed, and built the image (.sb file), Wrote the image, but USB doesn't work.

compared the MCUXPresso IDE generated plain bin and MCUXpresso Provisioning built plain image. There were only some differences. Please find the diff in the attachment.