![NXP Semiconductors LPC43Sxx Скачать руководство пользователя страница 102](http://html1.mh-extra.com/html/nxp-semiconductors/lpc43sxx/lpc43sxx_user-manual_1721827102.webp)
UM10503
All information provided in this document is subject to legal disclaimers.
© NXP B.V. 2015. All rights reserved.
User manual
Rev. 2.1 — 10 December 2015
102 of 1441
NXP Semiconductors
UM10503
Chapter 7: LPC43Sxx Boot ROM for secure parts
7.3.2.1 Development mode
A special development mode allows booting from a plain text image. This development
mode is active until the AES key1 has been programmed.
For parts with on-chip flash, the boot source is checked when the ISP pin is pulled LOW. All other flows are identical to flashless
parts. See
.
Fig 27. Boot flow for encrypted images (flashless parts)
check BOOT _SRC
valid
header ?
yes
no
yes
valid
encrypted
header
and image
hash
authentic
decrypt image to SRAM
at 0x1000 0000
yes
set program counter
= 0x1000 0000,
run
copy image to
SRAM at
0x1000 0000
Reset
no
set program counter
= 0x1000 0000,
run
valid
header ?
no
no
60s timeout
toggle pin
P1_1
header
present?
AES
key1
programmed?
no
no
no
no
AES key1
programmed?
yes
valid
encrypted
header
and image
hash
authentic
yes
no
yes
AES key1
programmed?
boot source =
UART, USB, SSP
boot source
= EMC, SPIFI
RESET
disable
IRQ &
MPU
CPU clock
= IRC
12MHz
AES
key1
programmed?
ISP pin
P2_7
LOW ?
load AES
key
yes
enable
JTAG
no
no
CPU clock
=
96MHz
enter ISP
mode (USART0)
yes
decrypt image to SRAM
at 0x1000 0000
set program counter
= 0x1000 0000,
run