Boot-Mode Execution Procedure: Figure 19.4 shows the boot-mode execution procedure.
1. Program the H8/3434F pins for boot mode, and start the
Start
H8/3434F from a reset.
2. Set the host’s data format to 8 bits + 1 stop bit, select the
Program H8/3434F pins for boot mode,
1
2
desired bit rate (2400, 4800, or 9600 bps), and transmit
H'00 data continuously.
and reset
Host transmits H'00 data continuously
at desired bit rate
3. The H8/3434F repeatedly measures the low period of the
RxD1 pin and calculates the host’s asynchronous-
communication bit rate.
H8/3434F measures low period
of H'00 data transmitted from host
4. When SCI bit-rate alignment is completed, the H8/3434F
transmits one H'00 data byte to indicate completion of
alignment.
3
4
H8/3434F computes bit rate and
sets bit rate register
5. The host should receive the byte transmitted from the
H8/3434F to indicate that bit-rate alignment is completed,
check that this byte is received normally, then transmit one
H'55 byte.
After completing bit-rate alignment, H8/3434F
sends one H'00 data byte to host to indicate
that alignment is completed
6. After receiving H'55, H8/3434F sends part of the boot
program to H'FB80 to H'FBDF and H'FC00 to H'FF2F of
RAM.
Host checks that this byte, indicating
completion of bit-rate alignment, is received
normally, then transmits one H'55 byte
5
6
7. After branching to the boot program area (H'FC00 to
H'FF2F) in RAM, the H8/3434F checks whether the flash
memory already contains any programmed data. If so, all
blocks are erased.
After receiving H'55, H8/3434F sends part of
the boot program to RAM
H8/3434F branches to the RAM boot
area (H'FC00 to H'FF2F), then checks the
data in the user area of flash memory
8. After the H8/3434F transmits one H'AA data byte, the host
transmits the byte length of the user program to be
transferred to the H8/3434F. The byte length must be sent
as two-byte data, upper byte first and lower byte second.
After that, the host proceeds to transmit the user program.
As verification, the H8/3434F echoes each byte of the
received byte-length data and user program back to the
host.
7
8
No
All data = H'FF?
Erase all flash
*3
Yes
memory blocks
9. The H8/3434F stores the received user program in on-chip
RAM in a 910-byte area from H'FBE0 to H'FF6D.
After checking that all data in flash memory is H'FF,
H8/3434F transmits one H'AA data byte to host
10. After transmitting one H'AA data byte, the H8/3434F
branches to address H'FBE0 in on-chip RAM and executes
the user program stored in the area from H'FBE0 to
H'FF6D.
H8/3434F receives two bytes indicating byte
length (N) of program to be downloaded
*1
to on-chip RAM
Notes: *1 The user can use 910 bytes of RAM. The number
of bytes transferred must not exceed 910 bytes. Be
sure to transmit the byte length in two bytes, upper
byte first and lower byte second. For example, if the
byte length of the program to be transferred is 256
bytes (H'0100), transmit H'01 as the upper byte,
followed by H'00 as the lower byte.
H8/3434F transfers one user program
*2
byte to RAM
H8/3434F calculates number of bytes left
to be transferred (N = N – 1)
9
No
All bytes transferred?
*2 The part of the user program that controls the flash
memory should be coded according to the flash
memory program/erase algorithms given later.
(N = 0?)
Yes
*3 If a memory cell malfunctions and cannot be
erased, the H8/3434F transmits one H'FF byte to
report an erase error, halts erasing, and halts
further operations.
After transferring the user program to RAM,
H8/3434F transmits one H'AA data byte to host
10
H8/3434F branches to H'FBE0 in RAM area and
executes user program downloaded into RAM
Figure 19.4 Boot Mode Flowchart
387
HITACHI [ HITACHI SEMICONDUCTOR ]
