Rev. 1.0, 09/01, page 232 of 904
In the external bus released state, internal bus masters except the EXDMAC can perform accesses
using the internal bus. When an internal bus master wants to make an external access, it
temporarily defers initiation of the bus cycle, and waits for the bus request from the external bus
master to be canceled. If a refresh request is generated in the external bus released state, or if a
SLEEP instruction is executed to place the chip in software standby mode or all-module-clocks-
stopped mode, refresh control and software standby or all-module-clocks-stopped control is
deferred until the bus request from the external bus master is canceled.
If the BREQOE bit is set to 1 in BCR, the
%5(42
pin can be driven low when any of the
following requests are issued, to request cancellation of the bus request externally.
•
When an internal bus master wants to perform an external access
•
When a refresh request is generated
•
When a SLEEP instruction is executed to place the chip in software standby mode or all-
module-clocks-stopped mode
When the
%5(4
pin is driven high, the
%$&.
pin is driven high at the prescribed timing and the
external bus released state is terminated.
If an external bus release request and external access occur simultaneously, the order of priority is
as follows:
(High) External bus release > External access by internal bus master (Low)
If a refresh request and external bus release request occur simultaneously, the order of priority is
as follows:
(High) Refresh > External bus release (Low)
Содержание H8S/2376 F-ZTAT
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