H8SX1663 datasheet(465/1158 Pages) RENESAS

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Section 8 Data Transfer Controller (DTC)

Rev.1.00 Jun. 07, 2006 Page 413 of 1102

REJ09B0294-0100

8.5.2

Transfer Information Read Skip Function

By setting the RRS bit of DTCCR, the vector address read and transfer information read can be

skipped. The current DTC vector number is always compared with the vector number of previous

activation. If the vector numbers match when RRS = 1, a DTC data transfer is performed without

reading the vector address and transfer information. If the previous activation is a chain transfer,

the vector address read and transfer information read are always performed. Figure 8.6 shows the

transfer information read skip timing.

To modify the vector table and transfer information, temporarily clear the RRS bit to 0, modify the

vector table and transfer information, and then set the RRS bit to 1 again. When the RRS bit is

cleared to 0, the stored vector number is deleted, and the updated vector table and transfer

information are read at the next activation.

Clock

Vector read

Note: Transfer information read is skipped when the activation sources of (1) and (2) (vector numbers) are the same while RRS = 1.

(1)

(2)

Transfer information

read

Data

transfer

Transfer information

write

Address

DTC activation

request

DTC request

Transfer

information

read skip

Data

transfer

Transfer information

write

Figure 8.6 Transfer Information Read Skip Timing

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