EMIF
7.3.5.5
SDRAM_REF_CTRL Register (offset = 10h) [reset = 0h]
SDRAM_REF_CTRL is shown in
and described in
Figure 7-95. SDRAM_REF_CTRL Register
31
30
29
28
27
26
25
24
reg_initref_dis
Reserved
reg_srt
reg_asr
Reserved
reg_pasr
R/W-0h
R-0h
R/W-0h
R/W-0h
R-0h
R/W-0h
23
22
21
20
19
18
17
16
Reserved
R-0h
15
14
13
12
11
10
9
8
reg_refresh_rate
R/W-0h
7
6
5
4
3
2
1
0
reg_refresh_rate
R/W-0h
LEGEND: R/W = Read/Write; R = Read only; W1toCl = Write 1 to clear bit; -n = value after reset
Table 7-115. SDRAM_REF_CTRL Register Field Descriptions
Bit
Field
Type
Reset
Description
31
reg_initref_dis
R/W
0h
Initialization and Refresh disable.
When set to 1, EMIF will disable SDRAM initialization and refreshes,
but will carry out SDRAM write/read transactions.
30
Reserved
R
0h
29
reg_srt
R/W
0h
DDR3 Self Refresh temperature range.
Set to 0 for normal operating temperature range and set to 1 for
extended operating temperature range when the reg_asr field is set
to 0.
This bit must be set to 0 if the reg_asr field is set to 1.
A write to this field will cause the EMIF to start the SDRAM
initialization sequence.
28
reg_asr
R/W
0h
DDR3 Auto Self Refresh enable.
Set to 1 for auto Self Refresh enable.
Set to 0 for manual Self Refresh reference indicated by the reg_srt
field.
A write to this field will cause the EMIF to start the SDRAM
initialization sequence.
27
Reserved
R
0h
26-24
reg_pasr
R/W
0h
Partial Array Self Refresh.
These bits get loaded into the Extended Mode Register of an
LPDDR1 or DDR3 during initialization.
For LPDDR1, set to 0 for full array, set to 1 for 1/2 array, set to 2 for
1/4 array, set to 5 for 1/8 array, and set to 6 for 1/16 array to be
refreshed.
For DDR3, set to 0 for full array, set to 1 or 5 for 1/2 array, set to 2
or 6 for 1/4 array, set to 3 or 7 for 1/8 array, and set to 4 for 3/4
array to be refreshed.
All other values are reserved.
A write to this field will cause the EMIF to start the SDRAM
initialization sequence.
23-16
Reserved
R
0h
15-0
reg_refresh_rate
R/W
0h
Refresh Rate.
Value in this field is used to define the rate at which connected
SDRAM devices will be refreshed.
SDRAM refresh rate = EMIF rate / reg_refresh_rate where EMIF rate
is equal to DDR clock rate.
If reg_refresh_rate < (8*regrre20 then it will
be loaded with (8*regrre20.
This is done to avoid lock-up situations when illegal values are
programmed.
429
SPRUH73H – October 2011 – Revised April 2013
Memory Subsystem
Copyright © 2011–2013, Texas Instruments Incorporated