HD6412373R RENESAS [Renesas Technology Corp], HD6412373R Datasheet - Page 344

• Manufacturer Part Number: HD6412373R
• Description: Renesas 16-Bit Single-Chip Microcomputer H8S Family/H8S/2300 Series
• Manufacturer: RENESAS [Renesas Technology Corp]

Section 6 Bus Controller (BSC)
EXDMAC: The EXDMAC sends the bus arbiter a request for the bus when an activation request
is generated.
As the EXDMAC is used exclusively for transfers to and from the external bus, if the bus is
transferred to the EXDMAC, internal accesses by other internal bus masters are still executed in
parallel.
In normal transfer mode or cycle steal transfer mode, the EXDMAC releases the bus after a single
transfer.
In block transfer mode, it releases the bus after transfer of one block, and in burst transfer mode,
after completion of the transfer. By setting the BGUP bit to 1 in EDMDR, it is possible to specify
temporary release of the bus in the event of an external access request from an internal bus master.
For details see section 8, EXDMA Controller (EXDMAC).
Note: Not supported by the H8S/2375, H8S/2375R, H8S/2373, and H8S/2373R.
External Bus Release: When the BREQ pin goes low and an external bus release request is
issued while the BRLE bit is set to 1 in BCR, a bus request is sent to the bus arbiter.
External bus release can be performed on completion of an external bus cycle.
6.13
Bus Controller Operation in Reset
In a reset, this LSI, including the bus controller, enters the reset state immediately, and any
executing bus cycle is aborted.
Rev.7.00 Mar. 18, 2009 page 276 of 1136
REJ09B0109-0700