H8SLASH3028F datasheet(180/923 Pages) RENESAS

180 / 923 page

Rev. 2.00, 09/03, page 150 of 890

6.5

DRAM Interface

6.5.1

Overview

The H8/3028 Group is provided with a DRAM interface with functions for DRAM control signal

(

RAS, UCAS, LCAS, WE) output, address multiplexing, and refreshing, that direct connection of

DRAM. In the expanded modes, external address space areas 2 to 5 can be designated as DRAM

space accessed via the DRAM interface. A data bus width of 8 or 16 bits can be selected for

DRAM space by means of a setting in ABWCR. When a 16-bit data bus width is selected, CAS is

used for byte access control. In the case of

× 16-bit organization DRAM, therefore, the 2-CAS

type can be connected. A fast page mode is supported in addition to the normal read and write

access modes.

6.5.2

DRAM Space and

RAS

RAS Output Pin Settings

Designation of areas 2 to 5 as DRAM space, and selection of the

RAS output pin for each area

designated as DRAM space, is performed by setting bits in DRCRA. Table 6.5 shows the

correspondence between the settings of bits DRAS2 to DRAS0 and the selected DRAM space and

RAS output pin.

When an arbitrary value has been set in DRAS2 to DRAS0, a write of a different value other than

000 must not be performed.

H8/3028F 数据表(PDF) 180 Page - Renesas Technology Corp