Boot-Mode Execution Procedure: Figure 19.4 shows the boot-mode execution procedure.
1. Program the H8/3334YF pins for boot mode, and start the
Start
H8/3334YF from a reset.
2. Set the host’s data format to 8 bits + 1 stop bit, select the
Program H8/3334YF 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 H8/3334YF repeatedly measures the low period of
the RxD1 pin and calculates the host’s asynchronous-
communication bit rate.
H8/3334YF measures low period
of H'00 data transmitted from host
4. When SCI bit-rate alignment is completed, the
H8/3334YF transmits one H'00 data byte to indicate
completion of alignment.
3
4
H8/3334YF computes bit rate and
sets bit rate register
5. The host should receive the byte transmitted from the
H8/3334YF 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, H8/3334YF
sends one H'00 data byte to host to indicate
that alignment is completed
6. After receiving H'55, H8/3334YF 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 H8/3334YF checks whether the
flash memory already contains any programmed data. If
so, all blocks are erased.
After receiving H'55, H8/3334YF sends part of
the boot program to RAM
H8/3334YF 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 H8/3334YF transmits one H'AA data byte, the
host transmits the byte length of the user program to be
transferred to the H8/3334YF. 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 H8/3334YF 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
Yes
*3
memory blocks
9. The H8/3334YF 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,
H8/3334YF transmits one H'AA data byte to host
10. After transmitting one H'AA data byte, the H8/3334YF
branches to address H'FBE0 in on-chip RAM and
executes the user program stored in the area from
H'FBE0 to H'FF6D.
H8/3334YF 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.
H8/3334YF transfers one user program
*2
byte to RAM
H8/3334YF calculates number of bytes left
9
to be transferred (N = N – 1)
No
All bytes transferred?
(N = 0?)
*2 The part of the user program that controls the
flash memory should be coded according to the
flash memory write/erase algorithms given later.
Yes
After transferring the user program to RAM,
H8/3334YF transmits one H'AA data byte to host
*3 If a memory cell malfunctions and cannot be
erased, the H8/3334YF transmits one H'FF byte
to report an erase error, halts erasing, and halts
further operations.
10
H8/3334YF branches to H'FBE0 in RAM area and
executes user program downloaded into RAM
Figure 19.4 Boot Mode Flowchart
385
RENESAS [ RENESAS TECHNOLOGY CORP ]
