HD64F3337YCP16V Datasheet, PDF (543/749 Pages) Renesas Technology Corp – Old Company Name in Catalogs and Other Documents

Start
Program H8/3337SF pins for boot mode, and
reset
Host transmits H'00 data continuously at desired
bit rate
H8/3337SF measures low period of H'00 data
transmitted from host
H8/3337SF computes bit rate and sets bit rate
register
After completing bit-rate alignment, H8/3337SF
sends one H'00 data byte to host to indicate that
alignment is completed
Host checks that this byte, indicating completion
of bit-rate alignment, is received normally, then
transmits one H'55 byte.
After receiving H'55, H8/3337SF sends part of
the boot program to RAM
After checking that all data in flash memory has
been erased, H8/3337SF transmits one H'AA
data byte to host
Check flash memory data, and if data has
already been written, erase all blocks
Host transmits byte length (N) of user program in
two bytes, upper byte followed by lower byte
H8/3337SF transmits received byte length to
host as verification data (echo-back)
n=1
Host transmits user program sequentially,
in byte units
H8/3337SF transmits received user program to
host as verification data (echo-back)
Transfer received on-board update routine to
on-chip RAM
No
n = N?
n+1→n
Yes
End of transfer
Transmit one H'AA data byte to host, and
execute on-board update routine transferred
to on-chip RAM
Note: If a memory cell malfunctions and cannot be erased, the H8/3337SF transmits one H'FF byte to report an erase
error, halts erasing, and halts further operations.
Figure 21.7 Boot Mode Flowchart
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