h8s-2646 Renesas Electronics Corporation., h8s-2646 Datasheet - Page 165

• Manufacturer Part Number: h8s-2646
• Description: Renesas 16-bit Single-chip Microcomputer H8s Family/h8s/2600 Series
• Manufacturer: Renesas Electronics Corporation.

7.1
The H8S/2646 Group has a built-in bus controller (BSC) that manages the external address space
divided into eight areas. The bus specifications, such as bus width and number of access states,
can be set independently for each area, enabling multiple memories to be connected easily.
The bus controller also has a bus arbitration function, and controls the operation of the internal bus
masters: the CPU, and data transfer controller (DTC).
7.1.1
The features of the bus controller are listed below.
• Manages external address space in area units
• Basic bus interface
• Burst ROM interface
• Idle cycle insertion
• Write buffer functions
• Bus arbitration function
• Other
 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
 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 can be set for area 0
 Choice of 1- or 2-state burst access
 An idle cycle can be inserted in case of an external read cycle between different areas
 An idle cycle can be inserted in case of an external write cycle immediately after an
 External write cycle and internal access can be executed in parallel
 Includes a bus arbiter that arbitrates bus mastership among the CPU and DTC
 External bus release function
external read cycle
Overview
Features
Section 7 Bus Controller
Rev. 5.00 Sep 22, 2005 page 139 of 1136
Section 7 Bus Controller
REJ09B0257-0500