HD6412373R RENESAS [Renesas Technology Corp], HD6412373R Datasheet - Page 351

• Manufacturer Part Number: HD6412373R
• Description: Renesas 16-Bit Single-Chip Microcomputer H8S Family/H8S/2300 Series
• Manufacturer: RENESAS [Renesas Technology Corp]

7.3.1
MAR is a 32-bit readable/writable register that specifies the source address (transfer source
address) or destination address (transfer destination address). MAR consists of two 16-bit registers
MARH and MARL. The upper 8 bits of MARH are reserved: they are always read as 0, and
cannot be modified.
The DMA has four MAR registers: MAR_0A in channel 0 (channel 0A), MAR_0B in channel 0
(channel 0B), MAR_1A in channel 1 (channel 1A), and MAR_1B in channel 1 (channel 1B).
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
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.
Memory Address Registers (MARA and MARB)
I/O Address Registers (IOARA and IOARB)
Rev.7.00 Mar. 18, 2009 page 283 of 1136
Section 7 DMA Controller (DMAC)
REJ09B0109-0700