h8s-2138 Renesas Electronics Corporation., h8s-2138 Datasheet - Page 577

• Manufacturer Part Number: h8s-2138
• Description: Renesas 16-bit Single-chip Microcomputer H8s Family/h8s/2100 Series
• Manufacturer: Renesas Electronics Corporation.

Provided in the H8S/2138 Group; not provided in the H8S/2134 Group.
17.1
The H8S/2138 Group has an on-chip host interface (HIF) that enables connection to an ISA bus,
widely used as the internal bus in personal computers. The host interface provides a dual-channel
parallel interface between the on-chip CPU and a host processor. The host interface is available
only when the HI12E bit is set to 1 in SYSCR2. This mode is called slave mode, because it is
designed for a master-slave communication system in which the H8S/2138 Group chip is slaved to
a host processor.
17.1.1
The features of the host interface are summarized below.
The host interface consists of 4-byte data registers, 2-byte status registers, a 1-byte control
register, fast A20 gate logic, and a host interrupt request circuit. Communication is carried out via
five control signals from the host processor (CS1, CS2 or ECS2, HA0, IOR, and IOW), four
output signals to the host processor (GA20, HIRQ1, HIRQ11, and HIRQ12), and an 8-bit
bidirectional command/data bus (HDB7 to HDB0). The CS1 and CS2 (or ECS2) signals select one
of the two interface channels.
Overview
Features
Section 17 Host Interface [H8S/2138 Group]
Section 17 Host Interface [H8S/2138 Group]
Rev. 4.00 Jun 06, 2006 page 523 of 1004
REJ09B0301-0400