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UM10503
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© NXP B.V. 2012. All rights reserved.
User manual
Rev. 1.3 — 6 July 2012
35 of 1269
NXP Semiconductors
UM10503
Chapter 5: LPC43xx Boot ROM
For flash-based and flashless parts alike, several external sources are available for
booting depending on the values of the OTP bits BOOT_SRC (see
). If the
OTP memory is not programmed or the BOOT_SRC bits are all zero, the boot mode is
determined by the states of the boot pins P2_9, P2_8, P1_2, and P1_1.
[1]
The boot loader programs the appropriate pin function at reset to boot using SSP0.
Table 18.
Boot mode when OTP BOOT_SRC bits are programmed
Boot mode
BOOT_SRC
bit 3
BOOT_SRC
bit 2
BOOT_SRC
bit 1
BOOT_SRC
bit 0
Description
Boot pins
0
0
0
0
Boot source is defined by the reset state of P1_1,
P1_2, P2_9, and P2_8 pins. See
USART0
0
0
0
1
Boot from device connected to USART0 using pins
P2_0 and P2_1. For flash parts, enter UART ISP
mode.
SPIFI
0
0
1
0
Boot from Quad SPI flash connected to the SPIFI
interface using pins P3_3 to P3_8.
EMC 8-bit
0
0
1
1
Boot from external static memory (such as NOR
flash) using CS0 and an 8-bit data bus.
EMC 16-bit
0
1
0
0
Boot from external static memory (such as NOR
flash) using CS0 and a 16-bit data bus.
EMC 32-bit
0
1
0
1
Boot from external static memory (such as NOR
flash) using CS0 and a 32-bit data bus.
USB0
0
1
1
0
Boot from USB0.
USB1
0
1
1
1
Boot from USB1.
SPI (SSP)
1
0
0
0
Boot from SPI flash connected to the SSP0
interface on P3_3 (function SSP0_SCK), P3_6
(function SSP0_MISO), P3_7 (function
SSP0_MOSI), and P3_8 (function SSP0_SSEL)
USART3
1
0
0
1
Boot from device connected to USART3 using pins
P2_3 and P2_4. For flash parts, enter UART ISP
mode.
Table 19.
Boot mode when OTP BOOT_SRC bits are zero
Boot mode
P2_9
P2_8
P1_2
P1_1
Description
USART0
LOW
LOW
LOW
LOW
Boot from device connected to USART0 using pins P2_0 and
P2_1. For flash parts, enter UART ISP mode.
SPIFI
LOW
LOW
LOW
HIGH
Boot from Quad SPI flash connected to the SPIFI interface on
P3_3 to P3_8
EMC 8-bit
LOW
LOW
HIGH
LOW
Boot from external static memory (such as NOR flash) using CS0
and an 8-bit data bus.
EMC 16-bit
LOW
LOW
HIGH
HIGH
Boot from external static memory (such as NOR flash) using CS0
and a 16-bit data bus.
EMC 32-bit
LOW
HIGH
LOW
LOW
Boot from external static memory (such as NOR flash) using CS0
and a 32-bit data bus.
USB0
LOW
HIGH LOW
HIGH
Boot
from
USB0.