4 protocol description(s), Table 3. truth table for ddr2 sdram commands, Peripheral architecture – Texas Instruments TMS320C6455 User Manual
Page 13
Peripheral Architecture
2.4
Protocol Description(s)
The DDR2 memory controller supports the DDR2 SDRAM commands listed in
.
shows the
signal truth table for the DDR2 SDRAM commands.
Table 2. DDR2 SDRAM Commands
Command
Function
ACTV
Activates the selected bank and row.
DCAB
Precharge all command. Deactivates (precharges) all banks.
DEAC
Precharge single command. Deactivates (precharges) a single bank.
DESEL
Device Deselect.
EMRS
Extended Mode Register set. Allows altering the contents of the mode register.
MRS
Mode register set. Allows altering the contents of the mode register.
NOP
No operation.
Power Down
Power down mode.
READ
Inputs the starting column address and begins the read operation.
READ with
Inputs the starting column address and begins the read operation. The read operation is followed by a
autoprecharge
precharge.
REFR
Autorefresh cycle.
SLFREFR
Self-refresh mode.
WRT
Inputs the starting column address and begins the write operation.
WRT with
Inputs the starting column address and begins the write operation. The write operation is followed by a
autoprecharge
precharge.
Table 3. Truth Table for DDR2 SDRAM Commands
DDR2 SDRAM
Signals
CKE
CS
RAS
CAS
WE
BA[2:0]
A[13:11, 9:0]
A10
DSDCKE
DDR2 Memory
Previous
Controller Signals
Cycles
Current Cycle
DCE0
DSDRAS
DSDCAS
DSDWE
DBA[2:0]
DEA[13:11, 9:0]
DEA[10]
ACTV
H
(1)
H
L
L
H
H
Bank
Row Address
DCAB
H
H
L
L
H
L
X
X
H
DEAC
H
H
L
L
H
L
Bank
X
L
MRS
H
H
L
L
L
L
BA
(2)
OP Code
EMRS
H
H
L
L
L
L
BA
OP Code
READ
H
H
L
H
L
H
BA
Column Address
L
READ with
H
H
L
H
L
H
BA
Column Address
H
precharge
WRT
H
H
L
H
L
L
BA
Column Address
L
WRT with precharge
H
H
L
H
L
L
BA
Column Address
L
REFR
H
H
L
L
L
H
X
X
X
SLFREFR
H
L
L
L
L
H
X
X
X
entry
SLFREFR
L
H
H
X
X
X
X
X
X
exit
L
H
H
H
X
X
X
NOP
H
X
L
H
H
H
X
X
X
DESEL
H
X
H
X
X
X
X
X
X
Power-down
H
L
H
X
X
X
X
X
X
entry
L
H
H
H
X
X
X
Power-down
L
H
H
X
X
X
X
X
X
exit
L
H
H
H
X
X
X
(1)
LEGEND: H = logic high; L = logic low; X = don
'
t care (either H or L).
(2)
BA refers to the bank address pins (BA[2:0]).
13
SPRU970G
–
December 2005
–
Revised June 2011
C6455/C6454 DDR2 Memory Controller
Copyright
©
2005
–
2011, Texas Instruments Incorporated