10 SDRAM CONTROLLER (SDRAMC)
10-10
Seiko Epson Corporation
S1C33L26 TECHNICAL MANUAL
Read/Write Cycles
10.5.4
Read cycle
The SDRAMC always reads data from the SDRAM in bursts. The burst length is fixed to 2. Figure 10.5.4.1
shows an example of timing chart when reading out 2-word data from the same row address.
Parameter setting example: CAS latency = 2, t
RCD
= 2 cycles, t
RAS
= 4 cycles, t
RP
= 2 cycles
SDCLK
Command
SDCKE
#SDCS
#SDRAS
#SDCAS
#SDWE
SDBA[1:0]
SDA10
SDA[12:11, 9:0]
DQMH/DQML
DQ[15:0]
ACTV
H
NOP
PRE NOP
READ NOP READ
BA
BA
ROW
D(1-1) D(1-2) D(2-1) D(2-2)
t
RCD
t
RP
CAS
latency
CAS
latency
ROW
COL1
BA
COL2
BA
5.4.1 Burst Read in the Same Page
Figure 10.
Figure 10.5.4.2 shows an example of a timing chart in cases where the row address is changed during burst
read.
Parameter setting example: CAS latency = 2, t
RCD
= 2 cycles, t
RAS
= 4 cycles, t
RP
= 2 cycles
SDCLK
Command
SDCKE
#SDCS
#SDRAS
#SDCAS
#SDWE
SDBA[1:0]
SDA10
SDA[12:11, 9:0]
DQMH/DQML
DQ[15:0]
ACTV
H
NOP
NOP
PRE NOP
READ
BA
BA
ROW1
D
(n)
D
(n+1)
D
(0)
D
(1)
t
RCD
t
RP
t
RCD
t
RP
CAS
latency
CAS
latency
ROW1
COLn
BA
ACTV NOP
PRE NOP
READ
BA
BA
ROW2
ROW2
COL0
BA
5.4.2 Changing Row Address During Burst Read
Figure 10.