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UM10503
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© NXP B.V. 2015. All rights reserved.
User manual
Rev. 2.1 — 10 December 2015
59 of 1441
NXP Semiconductors
UM10503
Chapter 5: LPC43xx Boot ROM
5.3.3 Boot image header format
Non-AES capable products may boot from an image with header or execute directly from
the boot source if the boot source is memory mapped (see
). When no valid
header is found, then the CPU will try to execute code from the first location of the
memory mapped boot source. The user should take care that this location contains
executable code, otherwise a hard fault exception will occur. This exception jumps to a
while(1) loop.
The image must be preceded by a header that has the layout described in
. For
encrypted images the header must be encrypted with the AES user key1 and initialization
vector iv = 0. The user key is stored in the OTP (see
). Non-encrypted images
may omit the header.
[1]
Can only be active if device is AES capable (secure part). Otherwise the image is considered invalid.
[2]
The image size should be set to no more than the size of the SRAM located at 0x1000 0000.
Table 23.
Boot image header use
Boot source
Memory mapped
Header required
USART0
no
yes
SPIFI
yes
no
EMC 8-bit
yes
no
EMC 16-bit
yes
no
EMC 32-bit
yes
no
USB0
no
yes
USB1
no
yes
SPI (SSP)
no
yes
USART3
no
yes
Table 24.
Boot image header description
Address
Name
Description
size [bits]
5:0
AES encryption active
0x25 (100101): AES encryption active
0x1A (011010): AES encryption not active
all other values: invalid image
6
7:6
HASH_ACTIVE
Indicates whether a hash is used:
00: reserved for non-secure parts.
01: reserved
10: reserved
11: no hash is used
2
15:8
RESERVED
11...11 (binary)
8
31:16
Size of image copied to internal SRAM at
boot time.
16
95:32
HASH_VALUE
Reserved for non-secure parts.
64
127:96
RESERVED
11...11 (binary)
32