181
In block transfer mode, it releases the bus after transfer of one block, and in burst mode, after
completion of the transfer. By setting the BGUP bit to 1 in the EDMDR register, 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 7, EXDMA Controller, in the H8S/2678 Series Hardware Manual.
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 the BCR register, a bus request is sent to the bus arbiter.
External bus release can be performed on completion of an external bus cycle.
4.11
Bus Controller Operation in a Reset
In a reset, the chip, including the bus controller, enters the reset state immediately, and any
executing bus cycle is aborted.
Содержание H8S/2670
Страница 5: ......
Страница 9: ......
Страница 199: ...182 ...
Страница 361: ...344 ...
Страница 393: ...376 ...
Страница 647: ...630 ...