Register 4: EPI SDRAM Configuration (EPISDRAMCFG), offset 0x010
Important:
The
MODE
field in the
EPICFG
register determines which configuration register is
accessed for offsets 0x010 and 0x014.
To access
EPISDRAMCFG
, the
MODE
field must be 0x1.
The SDRAM Configuration register is used to specify several parameters for the SDRAM controller.
Note that this register is reset when the
MODE
field in the
EPICFG
register is changed. If another
mode is selected and the SDRAM mode is selected again, the values must be reinitialized.
The SDRAM interface is designed to interface to x16 SDR SDRAMs of 64 MHz or higher, with the
address and data pins overlapped (wire ORed on the board). See Table 11-3 on page 823 for pin
assignments.
EPI SDRAM Configuration (EPISDRAMCFG)
Base 0x400D.0000
Offset 0x010
Type RW, reset 0x82EE.0000
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
RFSH
reserved
FREQ
RW
RW
RW
RW
RW
RW
RW
RW
RW
RW
RW
RO
RO
RO
RW
RW
Type
0
1
1
1
0
1
1
1
0
1
0
0
0
0
0
1
Reset
0
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
SIZE
reserved
SLEEP
reserved
RW
RW
RO
RO
RO
RO
RO
RO
RO
RW
RO
RO
RO
RO
RO
RO
Type
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
Reset
Description
Reset
Type
Name
Bit/Field
EPI Frequency Range
This field configures the frequency range used for delay references by
internal counters. This EPI frequency is the system frequency with the
divider programmed by the
COUNT0
bit in the
EPIBAUDn
register bit.
This field affects the power up, precharge, and auto refresh delays. This
field does not affect the refresh counting, which is configured separately
using the
RFSH
field (and is based on system clock rate and number of
rows per bank). The ranges are:
Description
Value
0 - 15 MHz
0x0
15 - 30 MHz
0x1
30 - 50 MHz
0x2
50 - 100 MHz
0x3
0x2
RW
FREQ
31:30
Software should not rely on the value of a reserved bit. To provide
compatibility with future products, the value of a reserved bit should be
preserved across a read-modify-write operation.
0x0
RO
reserved
29:27
Refresh Counter
This field contains the refresh counter in EPI clocks. The reset value of
0x2EE provides a refresh period of 64 ms when using a 50 MHz EPI
clock.
0x2EE
RW
RFSH
26:16
863
June 18, 2014
Texas Instruments-Production Data
Tiva
™
TM4C1294NCPDT Microcontroller