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M451
May. 4, 2018
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Multi-word Programming
The NuMicro
®
M451 supports multi-word programming function to speed up flash updated
procedure. The maximum programming length is up to 256 bytes, and the minimum programming
length is 8 bytes (2 words). The multi-word programming is the fastest programming function if the
programming words more than 8 bytes, because only one set of flash setup time and hold time
needed for one time operation.
32-bit
Programming
64-bit
Programming
Multi-Word
Programming
SETUP
TIME
fix 4 bytes programming
HOLD
TIME
SETUP
TIME
fix 8 bytes programming
HOLD
TIME
SETUP
TIME
8 ~ 256 bytes programming (8 bytes align)
HOLD
TIME
Time
Figure 6.4-12 Multi-word Programming Time
In multi-word programming operation, Cortex
®
-M4 CPU has to monitor the empty status of the
programming buffer. CPU has to prepare the next data for programming continuity. The multi-
program firmware should not be located in APROM or LDROM, because CPU instruction fetch
cannot be hold. The firmware has to be located in embedded SRAM of chip to avoid CPU hold.