Intel PXA255 User Manual
Page 198
6-16
Intel® PXA255 Processor Developer’s Manual
Memory Controller
18
K2RUN
SDRAM Clock Pin 2 (SDCLK<2>) Run Control/Status
0 – SDCLK2 disabled
1 – SDCLK2 enabled
K2RUN also can be cleared by program. Use with caution because the resulting state
prohibits automatic transitions for any commands.
Setting K1RUN and/or K2RUN is a part of the hardware and sleep reset procedure for
SDRAM.
17
K1DB2
SDRAM Clock Pin 1 (SDCLK1) Divide by 2 Control/Status
0 – SDCLK1 is same frequency as MEMCLK
1 – SDCLK1 runs at one-half the MEMCLK frequency
16
K1RUN
SDRAM Clock Pin 1 (SDCLK<1>) Run Control/Status
0 – SDCLK1 disabled
1 – SDCLK1 enabled
K1RUN can be cleared by software. Use with caution because the resulting state prohibits
automatic transitions for any commands.
Setting K1RUN and/or K2RUN is a part of the hardware and sleep reset procedure for
SDRAM.
15
E1PIN
SDRAM Clock Enable Pin 1 (SDCKE1) Level Control/Status
0 – SDCKE1 is disabled
1 – SDCKE1 is enabled
E1PIN can be cleared by program to cause a power-down command (if K1RUN=1 and/or
K2RUN=1, and SLFRSH=0). Use with caution because the resulting state prohibits
automatic transitions for mode register set, read, write, and refresh commands. E1PIN can
be set by program to cause a power-down-exit command (if K1RUN=1 and/or K2RUN=1,
and SLFRSH=0).
Setting E1PIN is a part of the hardware reset or sleep reset procedure for SDRAM.
14
K0DB2
Synchronous Static Memory Clock Pin 0 (SDCLK<0>) Divide by 2 Control/Status
0 – SDCLK0 runs at the memory clock frequency.
1 – SDCLK0 runs at one-half the memory clock frequency.
This bit is automatically set upon hardware or sleep reset.
Table 6-5. MDREFR Bit Definitions (Sheet 2 of 3)
0x4800_0004
MDREFR
Memory Controller
Bit
31 30 29 28 27 26 25 24 23 22 21 20 19 18 17 16 15 14 13 12 11 10 9
8
7
6
5
4
3
2
1
0
reserved
K2
F
R
E
E
K1
F
R
E
E
K0
F
R
E
E
SLFR
SH
reser
v
ed
AP
D
K2
D
B
2
K2
R
U
N
K1
D
B
2
K1
R
U
N
E1
PIN
K0
D
B
2
K0
R
U
N
E0
PIN
DRI
Reset 0
0
0
0
0
0
1
1
1
1
0
0
1
0
1
0
0
1
*
*
1
1
1
1
1
1
1
1
1
1
1
1
Bits
Name
Description