Atmel SAM9X25, Manual

Page: 433 / 1145

433
11054A–ATARM–27-Jul-11
SAM9X25
433
11054A–ATARM–27-Jul-11
SAM9X25
Figure 30-8. Write Command Followed By a Read Command without Burst Write Interrupt, Low-power DDR1-SDRAM
Device
In the case of a single write access, write operation should be interrupted by a read access but
DM must be input 1 cycle prior to the read command to avoid writing invalid data. See
Figure 30-
9 on page 433 .
Figure 30-9. Single Write Access Followed By A Read Access Low-power DDR1-SDRAM Devices
Twrd = BL/2 +2 = 8/2 +2 = 6
Twr = 1
SDCLK
col a col a
A[12:0]
NOP WRITE NOP READ BST NOP
COMMAND
0
BA[1:0]
DQS[1:0]
Dc Dd De Df Dg Dh Da Db Da Db
D[15:0]
3 0 3
DM[1:0]
Row a
col a
NOP PRCHG NOP ACT NOP WRITE NOP READ BST NOP
0
Data masked
SDCLK
A[12:0]
COMMAND
BA[1:0]
DQS[1:0]
Da Db
Da Db
D[15:0]
3 0
3
DM[1:0]