Memory Address Registers (Mar); I/O Address Register (Ioar) - Renesas H8S Series Hardware Manual

7.2.1

Memory Address Registers (MAR)

Bit : 31 30
MAR : — —
Initial value : 0 0
R/W : — —
Bit : 15 14
MAR :
Initial value :
* *
R/W : R/W R/W R/W R/W R/W R/W R/W R/W R/W R/W R/W R/W R/W R/W R/W R/W
MAR is a 32-bit readable/writable register that specifies the transfer source address or destination address.
The upper 8 bits of MAR are reserved: they are always read as 0, and cannot be modified.
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. For details, see section 7.2.4, DMA Control Register (DMACR).
MAR is not initialized by a reset or in standby mode.
7.2.2

I/O Address Register (IOAR)

Bit : 15 14
IOAR :
Initial value :
* *
R/W : R/W R/W R/W R/W R/W R/W R/W R/W R/W R/W R/W R/W R/W R/W R/W R/W
IOAR is a 16-bit readable/writable register that specifies the lower 16 bits of the transfer source address or destination
address. The upper 8 bits of the transfer address are automatically set to H'FF.
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 invalid in single address mode.
IOAR is not incremented or decremented each time a transfer is executed, so that the address specified by IOAR is fixed.
IOAR is not initialized by a reset or in standby mode.
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REJ09B0138-0600H
29 28 27 26 25
— — — — —
0 0 0 0 0
— — — — —
13 12 11 10 9
* * * * *
13 12 11 10 9
* * * * *
24 23 22 21 20
—
0 * * * *
— R/W R/W R/W R/W R/W R/W R/W R/W
8 7 6 5 4
* * * * *
8 7 6 5 4
* * * * *
19 18 17 16
* * * *
3 2 1 0
* * * *
3 2 1 0
* * * *
*: Undefined
*: Undefined