SDRAM Controller (SDRAMC)
21-22
Freescale Semiconductor
21.5.1.6.4
DDR2 Mode Register Definition
shows the mode register used by DDR2 SDRAMs. This is the SDRAM’s extended mode
register, and not the SDRAMC’s mode/extended mode register (SDMR) described in
“SDRAM Mode/Extended Mode Register (SDMR)
Table 21-13. Mobile DDR Extended-Mode Register Field Descriptions
Field
Description
BA1–BA0 Bank address. These must be set to 10 to select the extended mode register.
A11–A7
Reserved, must be cleared.
A6–A5
DS
Drive strength.
00 Full strength
01 Half strength
10 Quarter strength
11 One-eighth strength
A4–A3
TCSR
Temperature-compensated self-refresh. Check the SDRAM manufacturer’s spec because the use of the TCSR
settings can vary from memory to memory.
A2–A0
PASR
Partial array self refresh coverage.
000
Full array
001
Half array
010
Quarter array
101
One-eighth array
110
One-sixteenth array
All other settings are reserved.
BA1
BA0
A12
A11
A10
A9
A8
A7
A6
A5
A4
A3
A2
A1
A0
Field
0
0
PD
WR
DLL
TM
CL
BT
BL
Figure 21-12. DDR2 Mode Register
Table 21-14. DDR2 Mode Register Field Descriptions
Field
Description
BA1–BA0
Bank address. These must be zero to select the mode register
A12
PD
Active Power Down exit time.
0 Use Fast exit (Use t
XARD
)
1 Use Slow exit (Use t
XARDS
)
A11–A9
WR
Write recovery for precharge. The t
CK
max determines WR
min
and t
CK
min determines WR
max
. WR in
clock cycles is calculated by dividing t
WR
(in ns) by t
CK
(in ns) and rounding up to the next integer
(WR[cycles] = t
WR
(ns)/t
CK
(ns)). The mode register must be programmed to this value. This is also used
with t
RP
to determine t
DAL
.
000 Reserved
001 2
010 3
011 4
100 5
101 6
11x Reserved
Summary of Contents for MCF54455
Page 33: ...xxviii Freescale Semiconductor ...
Page 67: ...Freescale Semiconductor 1 ...
Page 125: ...Freescale Semiconductor 1 ...
Page 145: ...Enhanced Multiply Accumulate Unit EMAC 5 21 Freescale Semiconductor ...
Page 173: ...Cache 6 28 Freescale Semiconductor ...
Page 179: ...Static RAM SRAM 7 6 Freescale Semiconductor ...
Page 207: ...Power Management 9 16 Freescale Semiconductor ...
Page 323: ...Reset Controller Module 13 8 Freescale Semiconductor ...
Page 389: ...Pin Multiplexing and Control 16 44 Freescale Semiconductor ...
Page 575: ...PCI Bus Controller 22 58 Freescale Semiconductor ...
Page 600: ...Advanced Technology Attachment ATA Freescale Semiconductor 23 25 ...
Page 601: ...Freescale Semiconductor 1 ...
Page 842: ...I2 C Interface Freescale Semiconductor 33 16 ...
Page 843: ...Freescale Semiconductor 1 ...
Page 921: ...Revision History A 6 Freescale Semiconductor ...