HD6432633 Datasheet, PDF (149/1453 Pages) Renesas Technology Corp – Series of Microcomputers (MCUs: microcomputer units)

Section 3 MCU Operating Modes
3.1 Overview
3.1.1 Operating Mode Selection
The H8S/2633 Series has four operating modes (modes 4 to 7). These modes enable selection of
the CPU operating mode, enabling/disabling of on-chip ROM, and the initial bus width setting, by
setting the mode pins (MD2 to MD0).
Table 3-1 lists the MCU operating modes.
Table 3-1 MCU Operating Mode Selection
MCU
CPU
Operating
Operating
Mode
MD2 MD1 MD0 Mode
Description
External Data Bus
On-Chip Initial
ROM Width
Max.
Width
0*
000—
—
—
—
1*
1
2*
10
3*
1
4
1 0 0 Advanced On-chip ROM disabled, Disabled 16 bits 16 bits
expanded mode
5
1
8 bits
16 bits
6
10
On-chip ROM enabled, Enabled 8 bits
16 bits
expanded mode
7
1
Single-chip mode
—
Note: * Not available in the H8S/2633 Series.
The CPU’s architecture allows for 4 Gbytes of address space, but the H8S/2633 Series actually
accesses a maximum of 16 Mbytes.
Modes 4 to 6 are externally expanded modes that allow access to external memory and peripheral
devices.
The external expansion modes allow switching between 8-bit and 16-bit bus modes. After program
execution starts, an 8-bit or 16-bit address space can be set for each area, depending on the bus
controller setting. If 16-bit access is selected for any one area, 16-bit bus mode is set; if 8-bit
access is selected for all areas, 8-bit bus mode is set.
Note that the functions of each pin depend on the operating mode.
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