Hitachi H8S/2633 Hardware Manual page 291

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.

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

Do not specify internal space for transfer addresses in single address mode.

(high impedance)

Figure 8-17 Data Bus in Single Address Mode