H8SXSLASH1663R datasheet(401/1504 Pages) RENESAS

401 / 1504 page

Section 9 Bus Controller (BSC)

Rev. 2.00 Sep. 24, 2008 Page 369 of 1468

REJ09B0412-0200

Note, however, that the bus cannot be transferred in the following cases.

• During transfer information read

• During the first data transfer

• During transfer information write back

The DTC releases the bus when the consecutive transfer cycles completed.

(3)

DMAC

The DMAC sends the internal bus arbiter a request for the bus when an activation request is

generated. When the DMAC accesses an external bus space, the DMAC first takes control of the

bus from the internal bus arbiter and then requests a bus to the external bus arbiter.

After the DMAC takes control of the bus, it may continue the transfer processing cycles or release

the bus at the end of every bus cycle depending on the conditions.

The DMAC continues transfers without releasing the bus in the following case:

• Between the read cycle in the dual-address mode and the write cycle corresponding to the read

cycle

If no bus master of a higher priority than the DMAC requests the bus and the IBCCS bit in BCR2

is cleared to 0, the DMAC continues transfers without releasing the bus in the following cases:

• During 1-block transfers in the block transfer mode

• During transfers in the burst mode

In other cases, the DMAC transfers the bus at the end of the bus cycle.

(4)

EXDMAC

The EXDMAC sends the external bus arbiter a request for the bus when an activation request is

generated. If an internal bus master accesses the external space, the bus is passed to the EXDMAC

when the bus master can release the bus. Some EXDMAC transfers are continued once it takes

control of the bus. Some EXDMAC transfers are divided and it releases the bus for each transfer

cycle.

• Transfers are continued without bus release between a read cycle and the subsequent write

cycle in dual address mode

• Transfers are continued without bus release in cluster transfer mode

H8SX/1663R Datenblatt(PDF) 401 Page - Renesas Technology Corp