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MAR is not initialized by a reset or in standby mode.
Short Address Mode: In short address mode, MARA and MARB operate independently.
Whether MAR functions as the source address register or as the destination address register can be
selected by means of the DTDIR bit in DMACR.
MAR is incremented or decremented each time a byte or word transfer is executed, so that the
address specified by MAR is constantly updated.
Full Address Mode: In full address mode, MARA functions as the source address register, and
MARB as the destination address register.
MAR is incremented or decremented each time a byte or word transfer is executed, so that the
source or destination address is constantly updated.
7.3.2
I/O Address Registers (IOARA and IOARB)
IOAR is a 16-bit readable/writable register that specifies the lower 16 bits of the source address
(transfer source address) or destination address (transfer destination address). The upper 8 bits of
the transfer address are automatically set to H'FF.
The DMA has four IOAR registers: IOAR_0A in channel 0 (channel 0A), IOAR_0B in channel 0
(channel 0B), IOAR_1A in channel 1 (channel 1A), and IOAR_1B in channel 1 (channel 1B).
Whether IOAR functions as the source address register or as the destination address register can
be selected by means of the DTDIR bit in DMACR.
IOAR is not incremented or decremented each time a data transfer is executed, so the address
specified by IOAR is fixed.
IOAR is not initialized by a reset or in standby mode.
IOAR can be used in short address mode but not in full address mode.
7.3.3
Execute Transfer Count Registers (ETCRA and ETCRB)
ETCR is a 16-bit readable/writable register that specifies the number of transfers.
The DMA has four ETCR registers: ETCR_0A in channel 0 (channel 0A), ETCR_0B in channel 0
(channel 0B), ETCR_1A in channel 1 (channel 1A), and ETCR_1B in channel 1 (channel 1B).
ETCR is not initialized by a reset or in standby mode.
Rev. 2.00, 05/03, page 203 of 820
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