Hitachi H8S/2646 Hardware Manual page 707

Start
Set pins to boot mode
and execute reset-start
Host transfers data (H'00)
continuously at prescribed bit rate
LSI measures low period
of H'00 data transmitted by host
LSI calculates bit rate and
sets value in bit rate register
After bit rate adjustment, LSI
transmits one H'00 data byte to
host to indicate end of adjustment
Host confirms normal reception
of bit rate adjustment end
indication (H'00), and transmits
one H'55 data byte
After receiving H'55,
LSI transmits one H'AA
data byte to host
Note: If a memory cell does not operate normally and cannot be erased, one H'FF byte is
transmitted as an erase error, and the erase operation and subsequent operations
are halted.
Figure 20-7 Boot Mode Execution Procedure
Host transmits number
of programming control program
bytes (N), upper byte followed
by lower byte
LSI transmits received
number of bytes to host as verify
data (echo-back)
n = 1
Host transmits programming control
program sequentially in byte units
LSI transmits received
programming control program to
host as verify data (echo-back)
Transfer received programming
control program to on-chip RAM
n = N?
Yes
End of transmission
Check flash memory data, and
if data has already been written,
erase all blocks
After confirming that all flash
memory data has been erased,
LSI transmits one H'AA data
byte to host
Execute programming control
program transferred to on-chip RAM
n + 1 → n
No
675