H8SSLASH2225 datasheet(251/1071 Pages) RENESAS

251 / 1071 page

Section 7 Bus Controller

Rev. 5.00 Aug 08, 2006 page 165 of 982

REJ09B0054-0500

Section 7 Bus Controller

This LSI has a built-in bus controller (BSC) that manages the external address space divided into

eight areas. The bus controller also has a bus arbitration function, and controls the operation of the

internal bus masters: the CPU, DMA controller (DMAC)*, and data transfer controller (DTC).

Note: * Supported only by the H8S/2239 Group.

7.1

Features

• Manages external address space in area units

 Manages the external space as 8 areas of 2-Mbytes

 Bus specifications can be set independently for each area

 Burst ROM interface can be set

• Basic bus interface

 Chip select (CS7 to CS0) can be output for areas 7 to 0

 8-bit access or 16-bit access can be selected for each area

 2-state access or 3-state access can be selected for each area

 Program wait states can be inserted for each area

• Burst ROM interface

 Burst ROM interface can be selected for area 0

 One or two states can be selected for the burst cycle

• Idle cycle insertion

 Idle cycle can be inserted between consecutive read accesses to different areas

 Idle cycle can be inserted before a write access to an external area immediately after a read

access to an external area

• Bus arbitration

 The on-chip bus arbiter arbitrates bus mastership among CPU, DMAC*, and DTC.

• Other features

 External bus release function

Note: * Supported only by the H8S/2239 Group.

H8S/2225 数据表(PDF) 251 Page - Renesas Technology Corp