UM10462
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User manual
Rev. 5.5 — 21 December 2016
422 of 523
NXP Semiconductors
UM10462
Chapter 20: LPC11U3x/2x/1x Flash programming firmware
20.16.4.6 Flash module status clear register
The FMSTATCLR register is used to clear the signature generation completion flag.
20.16.4.7 Algorithm and procedure for signature generation
Signature generation
A signature can be generated for any part of the flash contents. The address range to be
used for signature generation is defined by writing the start address to the FMSSTART
register, and the stop address to the FMSSTOP register.
The signature generation is started by writing a ‘1’ to the SIG_START bit in the FMSSTOP
register. Starting the signature generation is typically combined with defining the stop
address, which is done in the STOP bits of the same register.
The time that the signature generation takes is proportional to the address range for which
the signature is generated. Reading of the flash memory for signature generation uses a
self-timed read mechanism and does not depend on any configurable timing settings for
the flash. A safe estimation for the duration of the signature generation is:
Duration = int((60 / tcy) + 3) x (FMSSTOP - FM 1)
When signature generation is triggered via software, the duration is in AHB clock cycles,
and tcy is the time in ns for one AHB clock. The SIG_DONE bit in FMSTAT can be polled
by software to determine when signature generation is complete.
After signature generation, a 128-bit signature can be read from the FMSW0 to FMSW3
registers. The 128-bit signature reflects the corrected data read from the flash. The 128-bit
signature reflects flash parity bits and check bit values.
Content verification
Table 408. Flash module status register (FMSTAT - 0x4003 CFE0) bit description
Bit
Symbol
Description
Reset
value
1:0
-
Reserved, user software should not write ones to reserved bits.
The value read from a reserved bit is not defined.
NA
2
SIG_DONE
When 1, a previously started signature generation has
completed. See FMSTATCLR register description for clearing this
flag.
0
31:3
-
Reserved, user software should not write ones to reserved bits.
The value read from a reserved bit is not defined.
NA
Table 409. Flash module status clear register (FMSTATCLR - 0x0x4003 CFE8) bit description
Bit
Symbol
Description
Reset
value
1:0
-
Reserved, user software should not write ones to reserved
bits. The value read from a reserved bit is not defined.
NA
2
SIG_DONE_CLR
Writing a 1 to this bits clears the signature generation
completion flag (SIG_DONE) in the FMSTAT register.
0
31:3
-
Reserved, user software should not write ones to reserved
bits. The value read from a reserved bit is not defined.
NA