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Flash Memory Operation
5-11 Flash Memory Controller
Block Write
The block write can be used to accelerate the flash write process when many
sequential bytes or words need to be programmed. The flash programming
voltage remains on for the duration of writing the 64-byte block. The
cumulative programming time t
CPT
must not be exceeded for any block during
a block write.
A block write cannot be initiated from within flash memory. The block write
must be initiated from RAM only. The BUSY bit remains set throughout the
duration of the block write. The WAIT bit must be checked between writing
each byte or word in the block. When WAIT is set the next byte or word of the
block can be written. When writing successive blocks, the BLKWRT bit must
be cleared after the current block is complete. BLKWRT can be set initiating
the next block write after the required flash recovery time given by t
End
. BUSY
is cleared following each block write completion indicating the next block can
be written. Figure 5−10 shows the block write timing.
Figure 5−10. Block-Write Cycle Timing
BUSY
WAIT
Generate
Programming Operation Active
t
Block,
0
= 30/f
FTG
t
Block
1-63
= 21/f
FTG
Write to Flash e.g., MOV #123h, &Flash
BLKWRT bit
t
Block,
1-63
= 21/f
FTG
t
End
= 6/f
FTG
Cumulative Programming Time t
CPT
∼=< 4ms, V
CC
Current Consumption is Increased
Programming Voltage
Remove
Programming Voltage