R01UH0823EJ0100 Rev.1.00 Page 363 of 1823
Jul 31, 2019
RX23W Group 18. DMA Controller (DMACA)
18.3.3 Address Update Function Using Offset
The source and destination addresses can be updated by fixing, increment, decrement, or offset addition. When the offset
addition is selected, the offset specified by the DMA offset register (DMOFR of DMAC0) is added to the address every
time the DMAC performs one data transfer. This function realizes a data transfer where addresses are allocated to
separated areas.
Offset subtraction can also be realized by setting a negative value in DMOFR of DMAC0. In this case, the negative value
must be 2’s complement.
Address update function using offset can be specified only for the DMAC0 channel.
Table 18.6 shows the address update method in each address update mode.
Note 1. When setting a negative value in the DMA offset register, the value must be 2’s complement. The 2's complement is obtained
by the following formula.
2’s complement of a negative offset value = ~ (offset) + 1 (~: bit inversion)
Table 18.6 Address Update Method in Each Address Update Mode
Address Update
Mode
Settings of
DMACm.DMAMD.SM[1:0] and
DMACm.DMAMD.DM[1:0] for
Address Update Modes
Address Update Method
(for Different SZ[1:0] Settings in DMTMD of DMACm)
SZ[1:0] = 00b SZ[1:0] = 01b SZ[1:0] = 10b
Address fixed 00b Fixed
Offset addition 01b +DMACm.DMOFR*
1
Increment 10b +1 +2 +4
Decrement 11b –1 –2 –4
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