D12320VF25IV Datasheet, PDF (324/1304 Pages) Renesas Technology Corp – Old Company Name in Catalogs and Other Documents

Section 7 DMA Controller (Not Supported in the H8S/2321)
Figure 7.28 shows a transfer example in which TEND output is enabled and word-size single
address mode transfer (read) is performed from external 8-bit, 2-state access space to an external
device.
φ
Address bus
RD
DACK
TEND
DMA read
DMA read
DMA read
DMA
dead
Bus
release
Bus
release
Bus
release
Last transfer
cycle
Bus
release
Figure 7.28 Example of Single Address Mode (Word Read) Transfer
A one-byte or one-word transfer is performed for one transfer request, and after the transfer the
bus is released. While the bus is released, one or more bus cycles are executed by the CPU or
DTC.
In the transfer end cycle (the cycle in which the transfer counter reaches 0), a one-state DMA dead
cycle is inserted after the DMA write cycle.
Rev.6.00 Sep. 27, 2007 Page 292 of 1268
REJ09B0220-0600