Registers
405
SPRUH82C – April 2013 – Revised September 2016
Copyright © 2013–2016, Texas Instruments Incorporated
DDR2/mDDR Memory Controller
14.4.2 SDRAM Configuration Register (SDCR)
The SDRAM configuration register (SDCR) contains fields that program the DDR2/mDDR memory
controller to meet the specification of the attached DDR2/mDDR memory. These fields configure the
DDR2/mDDR memory controller to match the data bus width, CAS latency, number of internal banks, and
page size of the attached DDR2/mDDR memory. Writing to the DDRDRIVE[1:0], CL, IBANK, and
PAGESIZE bit fields causes the DDR2/mDDR memory controller to start the DDR2/mDDR SDRAM
initialization sequence. The SDCR is shown in
and described in
Figure 14-21. SDRAM Configuration Register (SDCR)
31
28
27
26
25
24
Reserved
DDR2TERM1
IBANK_POS
MSDRAMEN
DDRDRIVE1
R-0
R/W-1
R/W-0
R/W-0
R/W-0
23
22
21
20
19
18
17
16
BOOTUNLOCK
DDR2DDQS
DDR2TERM0
DDR2EN
DDRDLL_DIS
DDRDRIVE0
DDREN
SDRAMEN
R/W-0
R/W-0
R/W-0
R/W-1
R/W-0
R/W-0
R/W-1
R/W-1
15
14
13
12
11
9
8
TIMUNLOCK
NM
Reserved
CL
Reserved
R/W-0
R/W-1
R-0
R/W-5h
R-0
7
6
4
3
2
0
Reserved
IBANK
Reserved
PAGESIZE
R-0
R/W-2h
R-0
R/W-0
LEGEND: R/W = Read/Write; R = Read only; -
n
= value after reset
Table 14-24. SDRAM Configuration Register (SDCR) Field Descriptions
Bit
Field
Value
Description
31-28
Reserved
0
Reserved
27
DDR2TERM1
0-3h
DDR2 termination resistor value. This bit is used in conjunction with the DDR2TERM0 bit to make a
2-bit field. This bit is writeable only when the BOOTUNLOCK bit is unlocked. See the DDR2TERM0
bit. Note that the reset value of DDR2TERM[1:0] = 10, these bits must be cleared and forced to 00
to disable the termination because the ODT feature is not supported.
26
IBANK_POS
Internal Bank position.
0
Normal addressing
1
Special addressing. Typically used with mobile DDR partial array self-refresh.
25
MSDRAMEN
Mobile SDRAM enable. Use this bit in conjunction with DDR2EN, DDREN, and SDRAMEN to
enable/disable mobile SDRAM. To change this bit value, use the following sequence:
1.
Write a 1 to the BOOTUNLOCK bit.
2.
Write a 0 to the BOOTUNLOCK bit along with the desired value of the MSDRAMEN bit.
0
Disable mobile SDRAM
1
Enable mobile SDRAM
24
DDRDRIVE1
0-3h
SDRAM drive strength. This bit is used in conjunction with the DDRDRIVE0 bit to make a 2-bit field.
This bit is writeable only when the BOOTUNLOCK bit is unlocked. See the DDRDRIVE0 bit.
23
BOOTUNLOCK
Boot Unlock. Controls the write permission settings for the DDR2TERM[1:0], MSDRAMEN,
DDRDRIVE[1:0], DDR2DDQS, DDR2EN, DDRDLL_DIS, DDREN and SDRAMEN bit fields. To
change these bits, use the following sequence:
1.
Write a 1 to the BOOTUNLOCK bit.
2.
Write a 0 to the BOOTUNLOCK bit along with the desired value of the DDR2TERM[1:0],
MSDRAMEN, DDRDRIVE[1:0], DDR2DDQS, DDR2EN, DDRDLL_DIS, DDREN and
SDRAMEN bits.
0
DDR2TERM[1:0], MSDRAMEN, DDRDRIVE[1:0], DDR2DDQS, DDR2EN, DDRDLL_DIS, DDREN
and SDRAMEN bit fields may not be changed.
1
DDR2TERM[1:0], MSDRAMEN, DDRDRIVE[1:0], DDR2DDQS, DDR2EN, DDRDLL_DIS, DDREN
and SDRAMEN bit fields may be changed.