SH7672 datasheet(238/1292 Pages) RENESAS

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Section 7

Bus State Controller (BSC)

Rev. 1.00 Nov. 14, 2007 Page 212 of 1262

REJ09B0437-0100

7.4.8

AC Characteristics Switching Register (ACSWR)

To use the SDRAM in clock mode 0 or 1, set the AC characteristics switching register (ACSWR)

and AC characteristics key switching register (ACKEYR). In clock mode 2 or 3, set nothing to

keep the initial value.

Only a special sequence can write to this register to prevent accidental erroneous write. The

setting procedure is shown in section 7.4.10, Sequence to Write to ACSWR. Read is done by the

normal longword.

0000000000000000

RRRRRRRRRRRRRRRR

0000000000000000

R/W

----------------

ACOSW[3:0]

Bit:

Initial value:

R/W:

Bit:

Initial value:

R/W:

Bit

Bit Name

Initial

Value

R/W

Description

31 to 4



All 0

Reserved

These bits are always read as 0. The write value

should always be 0.

3 to 0

ACOSW[3:0] 0000

R/W

AC Characteristics Switch

Specifies AC characteristics switching

0000: Not extend the delay time

1001: Switches characteristics and extends the delay

time

Others: Setting prohibited

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