M30620ECFS datasheet(97/621 Pages) RENESAS

97 / 621 page

Mitsubishi microcomputers

M16C / 62 Group

SINGLE-CHIP 16-BIT CMOS MICROCOMPUTER

DMAC

(3) The priorities of channels and DMA transfer timing

If a DMA transfer request signal falls on a single sampling cycle (a sampling cycle means one period from

the leading edge to the trailing edge of BCLK), the DMA request bits of applicable channels concurrently

turn to "1". If the channels are active at that moment, DMA0 is given a high priority to start data transfer.

When DMA0 finishes data transfer, it gives the bus right to the CPU. When the CPU finishes single bus

access, then DMA1 starts data transfer and gives the bus right to the CPU.

An example in which DMA transfer is carried out in minimum cycles at the time when DMA transfer

request signals due to external factors concurrently occur.

Figure 1.16.6 An example of DMA transfer effected by external factors.

BCLK

DMA0

DMA1

DMA0

request bit

DMA1

request bit

CPU

INT0

INT1

Obtainm

ent of the

bus right

An example in which DMA transmission is carried out in minimum

cycles at the time when DMA transmission request signals due to

external factors concurrently occur.

Figure 1.16.6. An example of DMA transfer effected by external factors

M30620ECFS Datasheet(PDF) 97 Page - Renesas Technology Corp