UM10429
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User manual
Rev. 1 — 20 October 2010
171 of 258
NXP Semiconductors
UM10429
Chapter 17: LPC1102 Flash memory programming firmware
17.9.1.4 Flash Module Status Clear register
The FMSTATCLR register is used to clear the signature generation completion flag.
17.9.2
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 FMSSTOP.MISR_START. Starting
the signature generation is typically combined with defining the stop address, which is
done in another field FMSSTOP.FMSSTOP 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.
If signature generation is triggered via JTAG, the duration is in JTAG tck cycles, and tcy is
the time in ns for one JTAG clock. Polling the SIG_DONE bit in FMSTAT is not possible in
this case.
Table 188. Flash module Status register (FMSTAT - 0x4003 CFE0) bit description
Bit
Symbol
Description
Reset
value
31:2
-
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
1:0
-
Reserved, user software should not write ones to reserved bits.
The value read from a reserved bit is not defined.
NA
Table 189. Flash Module Status Clear register (FMSTATCLR - 0x0x4003 CFE8) bit description
Bit
Symbol
Description
Reset
value
31:2
-
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
1:0
-
Reserved, user software should not write ones to reserved
bits. The value read from a reserved bit is not defined.
NA