266
In single address mode, on the other hand, transfer is performed between external space in which
either the transfer source or the transfer destination is specified by an address, and an external
device for which selection is performed by means of the
DACK
strobe, without regard to the
address. Figure 8-17 shows the data bus in single address mode.
External
memory
External
device
(Read)
(Write)
RD
HWR
,
LWR
A23 to A0
H8S/2633
D15 to D0
(high impedance)
DACK
Address bus
Data bus
Figure 8-17 Data Bus in Single Address Mode
When using the DMAC for single address mode reading, transfer is performed from external
memory to the external device, and the
DACK
pin functions as a write strobe for the external
device. When using the DMAC for single address mode writing, transfer is performed from the
external device to external memory, and the
DACK
pin functions as a read strobe for the external
device. Since there is no directional control for the external device, one or other of the above
single directions should be used.
Bus cycles in single address mode are in accordance with the settings of the bus controller for the
external memory area. On the external device side,
DACK
is output in synchronization with the
address strobe. For details of bus cycles, see section 8.5.11, DMAC Bus Cycles (Single Address
Mode).
Do not specify internal space for transfer addresses in single address mode.
Содержание H8S/2631
Страница 28: ...xviii Appendix G Package Dimensions 1154 ...
Страница 341: ...316 Transfer SAR or DAR DAR or SAR Block area First block Nth block Figure 9 8 Memory Mapping in Block Transfer Mode ...
Страница 918: ...905 ø DREQ0 DREQ1 tDRQS tDRQH Figure 25 19 DMAC DREQ Input Timing ...
Страница 955: ...943 A 2 Instruction Codes Table A 2 shows the instruction codes ...