SH7721 datasheet(408/1524 Pages) RENESAS

408 / 1524 page

Section 9

Bus State Controller (BSC)

Rev. 3.00 Jan. 18, 2008 Page 346 of 1458

REJ09B0033-0300

9.5.5

SDRAM Interface

(1)

SDRAM Direct Connection

The SDRAM that can be connected to this LSI is a product that has 11/12/13 bits of row address,

8/9/10 bits of column address, 4 or less banks, and uses the A10 pin for setting precharge mode in

read and write command cycles.

The control signals for direct connection of SDRAM are

RAS, CAS, RD/WR, DQMUU,

DQMUL, DQMLU, DQMLL, CKE,

CS2, and CS3. All the signals other than CS2 and CS3 are

common to all areas, and signals other than CKE are valid when

CS2 or CS3 is asserted. SDRAM

can be connected to up to 2 spaces. The data bus width of the area that is connected to SDRAM

can be set to 32 or 16 bits.

Burst read/single write (burst length 1) and burst read/burst write (burst length 1) are supported as

the SDRAM operating mode.

Commands for SDRAM can be specified by

RAS, CAS, RD/WR, and specific address signals.

These commands are shown below.

• NOP

• Auto-refresh (REF)

• Self-refresh (SELF)

• All banks precharge (PALL)

• Specified bank precharge (PRE)

• Bank active (ACTV)

• Read (READ)

• Read with precharge (READA)

• Write (WRIT)

• Write with precharge (WRITA)

• Write mode register (MRS)

The byte to be accessed is specified by DQMUU, DQMUL, DQMLU, and DQMLL. Reading or

writing is performed for a byte whose corresponding DQMxx is low. For details on the

relationship between DQMxx and the byte to be accessed, refer to section 9.5.1, Endian/Access

Size and Data Alignment.

SH7721 Datasheet(PDF) 408 Page - Renesas Technology Corp