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Operation in each mode is summarized below.
(1) Sequential mode
In response to a single transfer request, the specified number of transfers are carried out, one
byte or one word at a time. An interrupt request can be sent to the CPU or DTC when the
specified number of transfers have been completed. One address is specified as 24 bits, and the
other as 16 bits. The transfer direction is programmable.
(2) Idle mode
In response to a single transfer request, the specified number of transfers are carried out, one
byte or one word at a time. An interrupt request can be sent to the CPU or DTC when the
specified number of transfers have been completed. One address is specified as 24 bits, and the
other as 16 bits. The transfer source address and transfer destination address are fixed. The
transfer direction is programmable.
(3) Repeat mode
In response to a single transfer request, the specified number of transfers are carried out, one
byte or one word at a time. When the specified number of transfers have been completed, the
addresses and transfer counter are restored to their original settings, and operation is continued.
No interrupt request is sent to the CPU or DTC. One address is specified as 24 bits, and the
other as 16 bits. The transfer direction is programmable.
(4) Single address mode
In response to a single transfer request, the specified number of transfers are carried out
between external memory and an external device, one byte or one word at a time. Unlike dual
address mode, source and destination accesses are performed in parallel. Therefore, either the
source or the destination is an external device which can be accessed with a strobe alone, using
the DACK pin. One address is specified as 24 bits, and for the other, the pin is set
automatically. The transfer direction is programmable.
Modes (1), (2) and (3) can also be specified for single address mode.
(5) Normal mode
• Auto-request
By means of register settings only, the DMAC is activated, and transfer continues until the
specified number of transfers have been completed. An interrupt request can be sent to the
CPU or DTC when transfer is completed. Both addresses are specified as 24 bits.
Cycle steal mode: The bus is released to another bus master every byte or word transfer.
Burst mode: The bus is held and transfer continued until the specified number of transfers
have been completed.
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