
UM10413
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© NXP B.V. 2011. All rights reserved.
User manual
Rev. 1 — 16 December 2011
224 of 268
NXP Semiconductors
UM10413
MPT612 User manual
Table 212. Code read protection options
Name Pattern
programmed
in 0x000001FC
Description
CRP1
0x12345678
access to chip via the JTAG pins is disabled. This mode allows partial
flash update using the following ISP commands and restrictions:
•
write to RAM command cannot access RAM below 0x4000 0200
•
copy RAM to flash command cannot write to sector 0
•
erase command can erase sector 0 only when all sectors are
selected for erase
•
compare command is disabled
This mode is useful when CRP is required and flash field updates are
needed but all sectors cannot be erased. Since compare command is
disabled, in case of partial updates the secondary loader must
implement the checksum mechanism to verify the integrity of the flash.
CRP2
0x87654321
access to chip via the JTAG 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 JTAG pins is disabled. If a valid user code is
present in flash, sector 0ISP entry by pulling PIO14 LOW is disabled.
This mode effectively disables ISP override using pin PIO14. It is up to
the user’s application to provide a flash update mechanism using IAP
calls or to call the reinvoke ISP command if necessary.
Caution: If CRP3 is selected, no future factory testing can be
performed on the device.
Table 213. Code Read Protection hardware/software interaction
CRP option
User code
valid
PIO14 pin at
reset
JTAG enabled Enter ISP
mode
Partial flash
update in ISP
mode
No
no
X
yes
yes
yes
No
yes
HIGH
yes
no
n/a
No
yes
LOW
yes
yes
yes
CRP1
yes
HIGH
no
no
n/a
CRP1
yes
LOW
no
yes
yes
CRP2
yes
HIGH
no
no
n/a
CRP2
yes
LOW
no
yes
no
CRP3
yes
X
no
no
n/a
CRP1
no
X
no
yes
yes
CRP2
no
X
no
yes
no
CRP3
no
X
no
yes
no