Datasheet

Section 22 ROM (Mask ROM Version, H8S/2148 F-ZTAT, H8S/2147N F-ZTAT, H8S/2144 F-ZTAT, and H8S/2142 F-ZTAT)
Rev. 4.00 Sep 27, 2006 page 657 of 1130
REJ09B0327-0400
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.
Start
Set pins to boot program mode
and execute reset-start
Host transfers data (H'00)
continuously at prescribed bit rate
MCU measures low period
of H'00 data transmitted by host
MCU calculates bit rate and
sets value in bit rate register
After bit rate adjustment, 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,
MCU transfers part of boot
program to RAM
Host transmits number
of user program bytes (N),
upper byte followed by lower byte
MCU transmits received
number of bytes to host as verify
data (echo-back)
n = 1
Host transmits user program
sequentially in byte units
MCU transmits received user
program to host as verify data
(echo-back)
Transfer received programming
control program to on-chip RAM
n = N?
No
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,
MCU transmits one H'AA data
byte to host
Transmit one H'AA data byte to host,
and execute programming control
program transferred to on-chip RAM
n + 1 → n
Figure 22.8 Boot Mode Execution Procedure