HD6433044 Datasheet, PDF (594/867 Pages) Hitachi Semiconductor – Hitachi Single-Chip Microcomputer

RAM Area Allocation in Boot Mode: In boot mode, the H'3F0 bytes from H'FEF10 to H'FF2FF
in modes 5 and 7, and from H'FFEF10 to H'FFF2FF in mode 6 are reserved for use by the boot
program. The user program is transferred into the area from H'FF300 to H'FFEFF, in modes 5 and
7, and from H'FFF300 to H'FFFEFF in mode 6 (H'C00 bytes). The boot program area is used
during the transition to execution of the user program transferred into RAM.
H'FEF10
H'FFEF10
Boot
program
area^*1
Boot
program
area^*1
H'FF300
H'FFEFF
User program
transfer area
(H'C00 bytes)
H'FFF00
H'FFF0F
Reserved*²
Modes 5 and 7
H'FFF300
H'FFFEFF
H'FFFF00
H'FFFF0F
User program
transfer area
(H'C00 bytes)
Reserved*²
Mode 6
Notes:
1. This area is unavailable until the user program transferred into RAM enters execution state
(branch to H'FF300 in modes 5 and 7, and H'FFF300 in mode 6). After branching to the user
program area, the boot program is retained in the boot program area (H'FEF10 to H'FF2FF in
modes 5 and 7, and H'FFEF10 to H'FFF2FF in mode 6).
2. Do not use reversed areas.
Figure 18-12 RAM Areas in Boot Mode
Notes on Use of Boot Mode
1. When the H8/3048F comes out of reset in boot mode, it measures the low period of the input
at the SCI1’s RXD₁ pin. The reset should end with RXD₁ high. After the reset ends, it takes
about 100 states for the H8/3048F 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 are not
H'FF), all flash memory blocks are erased. Boot mode is for use when user program mode is
unavailable, e.g. the first time on-board programming is performed, or if the update program
activated in user program mode is accidentally erased.
3. Interrupts cannot be used while the flash memory is being programmed or erased.
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