Renesas SH7781 User Manual

Page 565

12. DDR2-SDRAM Interface (DBSC2)

Rev.1.00 Jan. 10, 2008 Page 535 of 1658

REJ09B0261-0100

MCK0,
MCK1

MA[14:11]
MA[9:0]

MBA[2:0]

MCKE

MCS

MRAS

MCAS

MWE

MA[10]

Invalid

MDQS[3:0]

MDQ[31:0]

MDM[3:0]

Invalid

PALL

Invalid

REF

SDRAM
command

High level

Figure 12.12 Auto-Refresh Operation

Figure 12.13 shows the self-refresh operation. In order to perform self-refresh operation, the
sequence must be observed. For details, refer to section 12.5.4, Self-Refresh Operation.

When performing processing according to the sequence in section 12.5.4, Self-Refresh Operation,
commands to be issued to the SDRAM are those shown in figure 12.13. Before the transition to
self-refresh, the PALL command is issued in software. Then, software is used to issue the REF
command, and the SLFRSH (self-refresh entry from IDLE) command is issued. The SDRAM
continues in self-refresh mode until self-refresh is cancelled in software. After issuing the
SLFRSHX (self-refresh exit) command in software, it is necessary to wait for the time (tXSNR)
specified in the datasheet for the SDRAM being used until issuing a REF command. A wait