Memory Controller

Figure 6-9. SDRAM_write

0ns

25ns

50ns

75ns

tRP = 2 clks tRCD = 2 clks tRAS = 2 clks CL = 2 clks

tRCD

CL

SDCLK

nSDCS

MA[24:0] row col

nSDRAS

nSDCAS

nWE

DATA

0

1

2

3

DQM[3:0] mask0 mask1 mask2 mask3

Figure 6-10. SDRAM 4-Beat Read/ 4-Beat Write To Different Partitions

DTC=00, CL = 2, tRP = 1 clk, tRCD = 1 clk

SDCLK[1]

SDCKE[1]

command

read(0)

pre(1)

act(1)

nop

write(1)

nop

nSDCS

0

1

1

nSDRAS

nSDCAS

 

 

 

 

MA[24:10]

col

bank

row

col

nWE

MD[31:0]

rd0_0 rd0_1 rd0_2 rd0_3

wd1_0 wd1_1 wd1_2 wd1_3

DQM[3:0]

0000

mask0

mask1

mask2

mask3

 

 

 

mask data bytes

RDnWR

Intel® PXA255 Processor Developer’s Manual

6-31

Page 213
Image 213
Intel PXA255 manual SDRAMwrite, SDCLK1 SDCKE1