Serial Downloader Mode

[anshulkhare]

Hello All,

i am working on IMX RT processor, i am able to enter into SDP mode from Application using ROM API and from selection of BOOT MODE pins. i would like to know, in what other conditions processor can enter into Serial Download mode.

for ex.

1. in case of any SW exception or hard fault, will it enter into serial download mode.

2. in case of any memory corruption while writing into flash, will it enter into serial download mode.

or if there is any other scenario, how it can enter into serial download mode.

Can anyone help me on this.

Thanks & Regards,

Anshul

[anshulkhare]

@jay_heng if the images is signed or signed and encrypted , in that case also will boot rom checks the image validity?

and in-case in above scenarios image is not proper will it enter in SDP mode?

Thanks & Regards,

Anshul 

[jay_heng]

Correct

[anshulkhare]

@jay_heng in case if secureboot is enabled, in that case is it possible to upgrade the user application from SDP mode, using sdphost and blhost? 

[jay_heng]

If HAB fuse bit is enabled on chip, you can still upgrade user app by sdphost/blhost. but you need to load signed flashloader binary by sdphost this time.

[jay_heng]

SDP mode is mainly used to upgrade app image. ROM API and BOOT MODE pin are the two main ways to enter this mode

SW exception or hard fault has nothing to do with SDP mode.

memory corruption while writing into flash may cause processor to enter SDP mode, if boot header of app image is destroyed.

In a word. if bootROM cannot find proper image in external memory during boot process, it will switch to SDP mode.

[anshulkhare]

@jay_heng Thank You for the reply.

is there any verification method present in bootRom to check the validity of proper image?before entering into SDP mode.

how bootRom checks image is not proper?

Thanks & Regards,

Anshul

[jay_heng]

One bootable image = FDCB + IVT + BD + Image

BootROM will check those boot headers (FDCB + IVT + BD) before jumping into image.