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On-Chip RAM Area Divisions in Boot Mode: In boot mode, the RAM area is divided into an
area used by the boot program and an area to which the user program is transferred via the SCI, as
shown in figure 17.8. The boot program area becomes available when a transition is made to the
execution state for the user program transferred to RAM.
Note: The boot program area cannot be used until a transition is made to the execution state
for the user program transferred to RAM. Note also that the boot program remains in
this area in RAM even after control branches to the user program.
Notes on Use of Boot Mode:
1. When the H8/3062F-ZTAT or H8/3062F-ZTAT R-mask version MCU comes out of reset in
boot mode, it measures the low period of the input at the SCI's RXD
2. In boot mode, if any data has been programmed into the flash memory (if all data is not H'FF),
all flash memory blocks are erased. Boot mode is for use when user program mode is
unavailable, such as the first time on-board programming is performed, or if the program
activated in user program mode is accidentally erased.
3. Interrupts cannot be used while the flash memory is being programmed or erased.
4. The RXD
and TXD
1
5. Before branching to the user program the MCU terminates transmit and receive operations by
the on-chip SCI (channel 1) (by clearing the RE and TE bits to 0 in the serial control register
(SCR)), but the adjusted bit rate value remains set in the bit rate register (BRR). The transmit
data output pin, TXD
in P9DR).
The contents of the CPU's internal general registers are undefined at this time, so these
registers must be initialized immediately after branching to the user program. In particular,
492
H'FFEF20
H'FFF3FF
H'FFF400
H'FFFF1F
Figure 17.8 RAM Areas in Boot Mode
lines should be pulled up on the board.
1
, goes to the high-level output state (P9
1
Boot program
area
User program
transfer area
DDR = 1 in P9DDR, P9
1
pin.
1
DR = 1
1
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