H8SSLASH2218 datasheet(242/750 Pages) RENESAS

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Section 7 DMA Controller (DMAC)

Rev.6.00 Jun. 03, 2008 Page 194 of 698

REJ09B0074-0600

7.4.7

DMAC Activation Sources

DMAC activation sources consist of internal interrupts, external requests, and auto-requests. The

activation sources that can be specified depend on the transfer mode, as shown in table 7.8.

Table 7.8

DMAC Activation Sources

Full Address Mode

Activation

Source

Short Address

Mode

Normal Mode

Block Transfer

Mode

Internal

ADI

Interrupt

TXI0

RXI0

TGI0A

TGI1A

TGI2A

USB request Low level input of the

DREQ

signal

Auto-request

Legend:

: Can be specified

×: Cannot be specified

Activation by Internal Interrupt: An interrupt request selected as a DMAC activation source can

be sent simultaneously to the CPU. For details, see section 5, Interrupt Controller.

With activation by an internal interrupt, the DMAC accepts the request independently of the

interrupt controller. Consequently, interrupt controller priority settings are not accepted.

If the DMAC is activated by an interrupt request that is not used as a CPU interrupt source (DTA =

1), the interrupt source flag is cleared automatically by the DMA transfer. With ADI, TXI, and

RXI interrupts, however, the interrupt source flag is not cleared unless the prescribed register is

accessed in a DMA transfer. If the same interrupt is used as an activation source for more than one

channel, the interrupt request flag is cleared when the highest-priority channel is activated first.

Transfer requests for other channels are held pending in the DMAC, and activation is carried out in

order of priority.

When DTE = 0, such as after completion of a transfer, a request from the selected activation

source is not sent to the DMAC, regardless of the DTA bit. In this case, the relevant interrupt

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