H8SX1663 datasheet(411/1158 Pages) RENESAS

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Section 7 DMA Controller (DMAC)

Rev.1.00 Jun. 07, 2006 Page 359 of 1102

REJ09B0294-0100

7.5.6

Address Update Function using Offset

The source and destination addresses are updated by fixing, increment/decrement by 1, 2, or 4, or

offset addition. When the offset addition is selected, the offset specified by the offset register

(DOFR) is added to the address every time the DMAC transfers the data access size of data. This

function realizes a data transfer where addresses are allocated to separated areas.

Figure 7.17 shows the address update method.

±0

+ offset

±1, 2, or 4

Address not

updated

Data access size

added to or subtracted

from address (addresses

are continuous)

Offset is added to address

(addresses are not

continuous)

(a) Address fixed

(b) Increment or decrement

by 1, 2, or 4

External memory

Figure 7.17 Address Update Method

In item (a), Address fixed, the transfer source or destination address is not updated indicating the

same address.

In item (b), Increment or decrement by 1, 2, or 4, the transfer source or destination address is

incremented or decremented by the value according to the data access size at each transfer. Byte,

word, or longword can be specified as the data access size. The value of 1 for byte, 2 for word, and

4 for longword is used for updating the address. This operation realizes the data transfer placed in

consecutive areas.

In item (c), Offset addition, the address update does not depend on the data access size. The offset

specified by DOFR is added to the address every time the DMAC transfers data of the data access

size.

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