Encrypt XIP: What is "SW pin on your board to enable XIP"?

[rshipman]

Document: AN12079.pdf: How to use i.MXRT Security Boot, Application Notes, Rev. 0, 10/2017

Section: 3.3.3. Download the image

Pages: 27

What does the author mean by the words:

"At last set the SW pin on your board to enable XIP and run the application. Remember to reset the SW pin selection to change the boot mode and enable XIP, then you can reset and run."

What is the SW pin selection? Do they mean the boot config DIP switches?

Why set and then reset to enable XIP?

[rshipman]

I looked at the schematic for the RT1020-EVK.

Dip switch SW8-1 controls the EncryptedXIP fuse bit (BOOT_CFG[0]) via GPIO_EMC_18 (I guess because the fuse isn't locked).

However it is not clear what the boot settings should be when EncryptedXIP is on. I presume set them for internal boot (or from fuses if these are set up correctly)?

[rshipman]

And the RT1050-EVKB uses SW5-1. This DIP switch is not fitted so you have to solder on your own or close the circuit in some other way during boot.

Encrypted XIP works ok on the RT1050-EVK, using SW5-1.

I have not yet managed to get Encrypted XIP to work on the RT1020-EVK.

[Yuri]

Hello,

  You are right, the SW pin relates to Boot Mode Configurations, based on board switches.

Switch (SW7-3 & SW7-4) is used to select the boot mode on the MIMXRT1050 EVK Board.

Use sheet 16 of the EVK (.pdf) scheme for more details.

https://www.nxp.com/webapp/Download?colCode=MIMXRT1050-EVK-DESIGNFILES-A1&appType=license 

 For i.MX RT1020 EVK, use sheet 14 of the EVK (.pdf) scheme for more details.

https://www.nxp.com/webapp/Download?colCode=MIMXRT1020-EVK-Design-Files 

  Note, different boot modes are applied for the Serial Downloader and the XIP.

  To apply the MFG tool BOOT_MODE[1:0] = 01 (Serial Downloader mode) should

be used. And BOOT_MODE[1:0] = 10 (Internal Boot mode) should be used for the XIP.

Have a great day,

Yuri.

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[rshipman]

Encrypted XIP works on the RT1020-EVK and the RT1050-EVKB.

[navoda]

Hi @rshipman ,

Can you please briefly explain the steps you took to get an encrypted XIP image running on RT1020-EVK?
I did the following steps and it didn't run.

- Generated a bootable XIP image from MCUXpresso IDE with XIP_BOOT_HEADER_ENABLE=0 (iled_blinky)
- Encrypted the image using the Secure Provisioning Tool
- Set BEE_KEY_SEL0 fuse to SW-GP2
- Burnt the user key to SW-GP2
- Set  the EncryptedXIP bit to 1
- Programmed the board
- Tried with DIP switch set to both configurations: 0010 and 1010. Neither of them worked.