UM10850
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User manual
Rev. 2.4 — 13 September 2016
421 of 464
NXP Semiconductors
UM10850
Chapter 31: LPC5410x Flash API
In case a CRP mode is enabled and access to the chip is allowed via the ISP, an
unsupported or restricted ISP command will be terminated with return code
CODE_READ_PROTECTION_ENABLED.
31.3.6.1 ISP entry protection
In addition to the three CRP modes, the user can prevent the sampling of the pin for
entering ISP mode and thereby release the pin for other applications. This is called the
NO_ISP mode. The NO_ISP mode can be entered by programming the pattern
0x4E69 7370 at location 0x0000 02FC.
The NO_ISP mode is identical to the CRP3 mode except for SWD access, which is
allowed in NO_ISP mode but disabled in CRP3 mode. The NO_ISP mode does not offer
any code protection.
31.3.7 ISP interrupt and SRAM use
31.3.7.1 Interrupts during IAP
The on-chip flash memory is not accessible during erase/write operations. When the user
application code starts executing, the interrupt vectors from the user flash area are active.
Before making any IAP call, either disable the interrupts or ensure that the user interrupt
vectors are active in RAM and that the interrupt handlers reside in RAM. The IAP code
does not use or disable interrupts.
31.3.7.2 RAM used by ISP command handler
Memory for the USART ISP commands is allocated dynamically.
31.3.7.3 RAM used by IAP command handler
Flash programming commands use the top 32 bytes of on-chip SRAM0,
0x0200 FFE0 - 0x0200 FFFF (see
for details of the SRAM configuration).
The maximum stack usage in the user allocated stack space is 128 bytes and grows
downwards.
Read Part ID
yes
yes
n/a
Read Boot code version
yes
yes
n/a
Compare
no
no
n/a
ReadUID
yes
yes
n/a
Table 475. ISP commands allowed for different CRP levels
ISP command
CRP1
CRP2
CRP3 (no entry in
ISP mode allowed)