19

Rev 0.7

64Mb Low Power DDR SDRAM

Advanced

DM masking

The DDR SDRAM has a data mask function that can be used in conjunction with data write cycle, not read cycle. When the data

mask is activated (DM high) during write operation, DDR SDRAM does not accept the corresponding data.(DM to data-mask latency

is zero).

DM must be issued at the rising or falling edge of data strobe.

0

1

2

3

4

5

6

7

8

CK

CK

Command

NOP

NOP

NOP

NOP

DQS

DQs

Figure.13 DM masking timing

< Burst Length=8 >

NOP

WRITE

NOP

NOP

NOP

Din 0 Din 1

Din 3

Din 2

Din 5

Din 4

Din 6 Din 7

masked by DM=H

DM