Datasheet

UM10398 All information provided in this document is subject to legal disclaimers. © NXP B.V. 2014. All rights reserved.
User manual Rev. 12.3 — 10 June 2014 449 of 547
NXP Semiconductors
UM10398
Chapter 26: LPC111x/LPC11Cxx Flash programming firmware
26.10.1.3 Flash Module Status register
The read-only FMSTAT register provides a means of determining when signature
generation has completed. Completion of signature generation can be checked by polling
the SIG_DONE bit in FMSTAT. SIG_DONE should be cleared via the FMSTATCLR
register before starting a signature generation operation, otherwise the status might
indicate completion of a previous operation.
26.10.1.4 Flash Module Status Clear register
The FMSTATCLR register is used to clear the signature generation completion flag.
26.10.2 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 - FMSSTART + 1)
Table 416. 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 417. 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