H8SLASH3028F datasheet(257/923 Pages) RENESAS

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Rev. 2.00, 09/03, page 227 of 890

7.4.7

DMAC Activation

The DMAC can be activated by an internal interrupt, external request, or auto-request. The

available activation sources differ depending on the transfer mode and channel as indicated in

table 7.11.

Table 7.11 DMAC Activation Sources

Short Address Mode

Full Address Mode

Activation Source

Channels

0A and 1A

Channels

0B and 1B

Normal

Block

IMIA0

IMIA1

IMIA2

ADI

TXI0

××

Internal

interrupts

RXI0

××

External

requests

Falling edge

DREQ

Low input at

DREQ

Auto-request

××

Activation by Internal Interrupts: When an interrupt request is selected as a DMAC activation

source and the DTE bit is set to 1, that interrupt request is not sent to the CPU. It is not possible

for an interrupt request to activate the DMAC and simultaneously generate a CPU interrupt.

When the DMAC is activated by an interrupt request, the interrupt request flag is cleared

automatically. If the same interrupt is selected to activate two or more channels, the interrupt

request flag is cleared when the highest-priority channel is activated, but the transfer request is

held pending on the other channels in the DMAC, which are activated in their priority order.

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