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RT1050 Encrypted XIP example sets BEE_KEY0_SEL to a reserved value?

Question asked by rshipman on Jan 29, 2020
Latest reply on Feb 11, 2020 by Felipe García

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

Section: 3.3.2. Generate SB file for FlexSPI NOR image encryption and programming

Pages: 25-27


The example .bd file contains the lines:


#6. Program BEE_KEY0_SEL and BEE_KEY1_SEL

load fuse 0x0000e000 > 0x06;


Which sets:


BEE_KEY0_SEL to 10 = Reserved

BEE_KEY1_SEL to 11 = From SW-GP2


Why is BEE_KEY0_SEL being set to a reserved value?


Presumably only bit 1 of these two fields (i.e. bits 0x460[13] and 0x460[15]) are actually observed by the ROM bootloader?