Datasheet

Section 8 EXDMA Controller (EXDMAC)
R01UH0309EJ0500 Rev. 5.00 Page 407 of 1408
Sep 24, 2012
H8S/2456, H8S/2456R, H8S/2454 Group
Section 8 EXDMA Controller (EXDMAC)
This LSI has a built-in dual-channel external bus transfer DMA controller (EXDMAC). The
EXDMAC can carry out high-speed data transfer, in place of the CPU, to and from external
devices and external memory with a DACK (EXDMA transfer notification) facility.
Note: This EXDMAC is not supported by the H8S/2454 Group.
8.1 Features
• Direct specification of 16-Mbyte address space
• Selection of byte or word transfer data length
• Maximum number of transfers: 16M (16,777,215)/infinite (free-running)
• Selection of dual address mode or single address mode
• Selection of cycle steal mode or burst mode as bus mode
• Selection of normal mode or block transfer mode as transfer mode
• Two kinds of transfer requests: external request and auto-request
• An interrupt request can be sent to the CPU at the end of the specified number of transfers.
• Repeat area designation function:
• Operation in parallel with internal bus master:
• Acceptance of a transfer request and the start of transfer processing can be reported to an
external device via the EDRAK pin.
• Module stop state can be set.