Datasheet

Section 3 MCU Operating Modes
Rev.7.00 Mar. 18, 2009 page 71 of 1136
REJ09B0109-0700
Section 3 MCU Operating Modes
3.1 Operating Mode Selection
The H8S/2378 0.18μm F-ZTAT Group and H8S/2378R 0.18μm F-ZTAT Group have six
operating modes (modes 1 to 5 and 7). The H8S/2377 and H8S/2377R have five operating modes
(modes 1 to 4 and 7). The H8S/2375 and H8S/2375R has four operating modes (modes 1, 2, 4, and
7). The H8S/2373 and H8S/2373R has two operating modes (modes 1 and 2). The operating mode
is selected by the setting of mode pins (MD2 to MD0).
Modes 1, 2, and 4 are externally expanded modes in which the CPU can access an external
memory and peripheral devices. In the externally expanded mode, each area can be switched to 8-
bit or 16-bit address space by the bus controller. If any one of the areas is set to 16-bit address
space, the bus mode is 16 bits. If all areas are set to 8-bit address space, the bus mode is 8 bits.
Mode 7 is a single-chip activation externally expanded mode in which the CPU can switch to
access an external memory and peripheral devices at the beginning of a program execution.
Mode 3 is a boot mode in which the flash memory can be programmed or erased. For details of the
boot mode, refer to section 21, Flash Memory (0.18-μm F-ZTAT Version), or section 20, Flash
Memory (0.35-μm F-ZTAT Version).
The settings for pins MD2 to MD0 should not be changed during operation.
Table 3.1 MCU Operating Mode Selection
External Data Bus
MCU
Operating
Mode
MD2 MD1 MD0
CPU
Operating
Mode
Description
On-Chip
ROM
Initial
Width
Max.
Value
1
*
1
0 0 1 Advanced Expanded mode with
on-chip ROM disabled
Disabled 16 bits 16 bits
2
*
1
0 1 0 Advanced Expanded mode with
on-chip ROM disabled
Disabled 8 bits 16 bits
3 0 1 1 Advanced Boot mode Enabled ⎯ 16 bits
4 1 0 0 Advanced Expanded mode with
on-chip ROM enabled
Enabled 8 bits 16 bits
5
*
2
1 0 1 Advanced User boot mode Enabled ⎯ 16 bits
7 1 1 1 Advanced Single-chip mode Enabled ⎯ 16 bits
Notes: 1. Only modes 1 and 2 may be used on ROM-less versions.
2. Available only for the H8S/2378 0.18μm F-ZTAT Group and H8S/2378R 0.18μm
F-ZTAT Group.