Section 3 Mcu Operating Modes; Operating Mode Selection - Hitachi H8S/2378, H8S/2378R Series Hardware Manual

3.1

Operating Mode Selection

The H8S/2378 Series has seven operating modes (modes 1 to 7). For each operating mode, pins
are given with different functions. An operating mode is selected by the setting of mode pins
(MD2 to MD0). Table 3.1 lists the operating modes of the MCU.
Modes 1, 2, and 4 to 6 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.
Modes 3 is a boot mode in which the flash memory can be programmed or erased. For details on
the boot mode, refer to section 20, ROM.
Do not change the MD2 to MD0 pin settings during operation.
Table 3.1 MCU Operating Mode Selection
MCU
Operating
1
Mode* MD2 MD1 MD0
1 0 0
2 0 1
3 0 1
4 1 0
5 1 0
6 1 1
7 1 1

Section 3 MCU Operating Modes

CPU
Operating
Mode
1 Advanced
0 Advanced
1 Advanced
0 Advanced
1 Advanced
0 Advanced
1 Advanced
Description
Expanded mode with
on-chip ROM disabled
Expanded mode with
on-chip ROM disabled
Boot mode
Expanded mode with
on-chip ROM enabled
Expanded mode with
on-chip ROM enabled
Expanded mode with
on-chip ROM enabled
Single-chip mode
External Data
Bus
On-Chip Initial Max.
ROM Width Value
Disabled 16 bits 16 bits
Disabled 8 bits 16 bits
Enabled — 16 bits
Enabled 8 bits 16 bits
Enabled 16 bits 16 bits
Enabled 8 bits 16 bits
Enabled — 16 bits
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