Registers
408
SPRUH82C – April 2013 – Revised September 2016
Copyright © 2013–2016, Texas Instruments Incorporated
DDR2/mDDR Memory Controller
14.4.3 SDRAM Refresh Control Register (SDRCR)
The SDRAM refresh control register (SDRCR) is used to configure the DDR2/mDDR memory controller to:
•
Enter and Exit the self-refresh and power-down states.
•
Enable and disable MCLK, stopping when in the self-refresh state.
•
Meet the refresh requirement of the attached DDR2/mDDR device by programming the rate at which
the DDR2/mDDR memory controller issues autorefresh commands.
The SDRCR is shown in
and described in
Figure 14-22. SDRAM Refresh Control Register (SDRCR)
31
30
29
24
23
22
16
LPMODEN
MCLKSTOPEN
Reserved
SR_PD
Reserved
R/W-0
R/W-0
R-0
R/W-0
R-0
15
0
RR
R/W-884h
LEGEND: R/W = Read/Write; R = Read only; -
n
= value after reset
Table 14-25. SDRAM Refresh Control Register (SDRCR) Field Descriptions
Bit
Field
Value
Description
31
LPMODEN
Low-power mode enable.
0
Disable low-power mode.
1
Enable low-power mode. The state of bit SR_PD selects either self-refresh or power-down
mode.
30
MCLKSTOPEN
MCLK stop enable.
0
Disables MCLK stopping, MCLK may not be stopped.
1
Enables MCLK stopping, MCLK may be stopped. The LPMODEN bit must be set to 1 before
setting the MCLKSTOPEN bit to 1.
29-24
Reserved
0
Reserved
23
SR_PD
Self-refresh or Power-down select. This bit is only in effect when the LPMODEN bit is set to 1;
this bit is ignored when the LPMODEN bit is cleared to 0.
0
Self-refresh mode.
1
Power-down mode.
22-16
Reserved
0
Reserved
15-0
RR
0-FFFFh
Refresh rate. Defines the rate at which the attached SDRAM devices will be refreshed. The
value of this field may be calculated with the following equation:
RR = SDRAM frequency/SDRAM refresh rate
where
SDRAM refresh rate
is derived from the SDRAM data sheet.