HD6432351 datasheet(295/1025 Pages) RENESAS

295 / 1025 page

Section 7 DMA Controller (DMAC)

Rev. 3.00 Sep 15, 2006 page 261 of 988

REJ09B0330-0300

Activation by Auto-Request

Auto-request activation is performed by register setting only, and transfer continues to the end.

With auto-request activation, cycle steal mode or burst mode can be selected.

In cycle steal mode, the DMAC releases the bus to another bus master each time a byte or word is

transferred. DMA and CPU cycles usually alternate.

In burst mode, the DMAC keeps possession of the bus until the end of the transfer, and transfer is

performed continuously.

Single Address Mode

The DMAC can operate in dual address mode in which read cycles and write cycles are separate

cycles, or single address mode in which read and write cycles are executed in parallel.

In dual address mode, transfer is performed with the source address and destination address

specified separately.

In single address mode, on the other hand, transfer is performed between external space in which

either the transfer source or the transfer destination is specified by an address, and an external

device for which selection is performed by means of the

DACK strobe, without regard to the

address. Figure 7.17 shows the data bus in single address mode.

HD6432351 데이터시트(PDF) 295 Page - Renesas Technology Corp