UM10462 All information provided in this document is subject to legal disclaimers. © NXP B.V. 2016. All rights reserved.
User manual Rev. 5.5 — 21 December 2016 399 of 523
NXP Semiconductors
UM10462
Chapter 20: LPC11U3x/2x/1x Flash programming firmware
Table 362. Code Read Protection (CRP) options
Name Pattern
programmed in
0x0000 02FC
Description
NO_ISP 0x4E69 7370 Prevents sampling of pin PIO0_1 for entering ISP mode. PIO0_1 is
available for other uses.
CRP1 0x12345678 Access to chip via the SWD pins is disabled. This mode allows
partial flash update using the following ISP commands and
restrictions:
• Write to RAM command should not access RAM below 0x1000
0300. Access to addresses below 0x1000 0200 is disabled.
• Copy RAM to flash command can not write to Sector 0.
• Erase command can erase Sector 0 only when all sectors are
selected for erase.
• Compare command is disabled.
• Read Memory command is disabled.
This mode is useful when CRP is required and flash field updates
are needed but all sectors can not be erased. Since compare
command is disabled in case of partial updates the secondary
loader should implement checksum mechanism to verify the integrity
of the flash.
CRP2 0x87654321 Access to chip via the SWD pins is disabled. The following ISP
commands are disabled:
• Read Memory
• Write to RAM
• Go
• Copy RAM to flash
• Compare
When CRP2 is enabled the ISP erase command only allows erasure
of all user sectors.
CRP3 0x43218765 Access to chip via the SWD pins is disabled. ISP entry by pulling
PIO0_1 LOW is disabled if a valid user code is present in flash
sector 0.
This mode effectively disables ISP override using PIO0_1 pin. It is
up to the user’s application to provide a flash update mechanism
using IAP calls or call reinvoke ISP command to enable flash update
via UART0.
Caution: If CRP3 is selected, no future factory testing can be
performed on the device.
Table 363. Code Read Protection hardware/software interaction
CRP option User Code
Valid
PIO0_1 pin at
reset
SWD enabled LPC11Uxx
enters USB or
UART ISP
mode
partial flash
update in ISP
mode
None No x Yes Yes Yes
None Yes High Yes No NA
None Yes Low Yes Yes Yes
CRP1 Yes High No No NA
CRP1 Yes Low No Yes Yes
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