Section 2. Mcu Operating Modes And Address Space; Overview; Mode Selection - Hitachi H8/329 Series Hardware Manual

Section 2. MCU Operating Modes and Address Space

2.1 Overview

2.1.1 Mode Selection

The H8/329 Series operates in three modes numbered 1, 2, and 3. The mode is selected by the
inputs at the mode pins (MD
The ROMless versions (HD6413298 and HD6413278) can be used only in mode 1 (expanded mode
with on-chip ROM disabled.)
Table 2-1. Operating Modes
Mode MD
1
Mode 0 Low
Mode 1 Low
Mode 2 High
Mode 3 High
Note: * If the RAME bit in the system control register (SYSCR) is cleared to 0, off-chip memory
can be accessed instead.
Modes 1 and 2 are expanded modes that permit access to off-chip memory and peripheral devices.
The maximum address space supported by these externally expanded modes is 64K bytes.
In mode 3 (single-chip mode), only on-chip ROM and RAM and the on-chip register field are used.
All ports are available for general-purpose input and output.
Mode 0 is inoperative in the H8/329 Series. Avoid setting the mode pins to mode 0.
and MD ) when the chip comes out of a reset. See table 2-1.
1 0
MD Address space
0
Low —
High Expanded
Low Expanded
High Single-chip
On-chip ROM
—
Disabled
Enabled
Enabled
15
On-chip RAM
—
Enabled*
Enabled*
Enabled