HD64F3028F25 Datasheet, PDF (627/925 Pages) Renesas Technology Corp – Hardware Manual Renesas 16-Bit Single-Chip Microcomputer H8 Family/H8/300H Series

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 18.7. The boot program area becomes available when a transition is made to the
execution state for the user program transferred to RAM.
H'FFBF20
Boot program
area
H'FFC71F
H'FFC720
User program
transfer area
H'FFFF1F
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.
Figure 18.7 RAM Areas in Boot Mode
Notes on Use of Boot Mode:
1. When the H8/3028F-ZTAT chip comes out of reset in boot mode, it measures the low period
of the input at the SCI’s RxD₁ pin. The reset should end with RxD₁ high. After the reset ends,
it takes about 100 states for the chip to get ready to measure the low period of the RxD₁ input.
2. In boot mode, if any data has been programmed into the flash memory (if all data is not 1), 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 RxD₁ and TxD₁ lines should be pulled up on the board.
5. Before branching to the user program the H8/3028F-ZTAT 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, TxD₁, goes to the high-level output state (P9₁DDR = 1 in
P9DDR, P9₁DR = 1 in P9DR).
Rev. 2.00, 09/03, page 595 of 890