
EPI Registers
1127
SLAU723A – October 2017 – Revised October 2018
Copyright © 2017–2018, Texas Instruments Incorporated
External Peripheral Interface (EPI)
16.5.4 EPISDRAMCFG Register (Offset = 0x10) [reset = 0x82EE0000]
EPI SDRAM Configuration (EPISDRAMCFG)
NOTE:
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
for pin assignments.
EPISDRAMCFG is shown in
and described in
.
Return to
Figure 16-33. EPISDRAMCFG Register
31
30
29
28
27
26
25
24
FREQ
RESERVED
RFSH
R/W-0x2
R-0x0
R/W-0x2EE
23
22
21
20
19
18
17
16
RFSH
R/W-0x2EE
15
14
13
12
11
10
9
8
RESERVED
SLEEP
RESERVED
R-0x0
R/W-0x0
R-0x0
7
6
5
4
3
2
1
0
RESERVED
SIZE
R-0x0
R/W-0x0
Table 16-17. EPISDRAMCFG Register Field Descriptions
Bit
Field
Type
Reset
Description
31-30
FREQ
R/W
0x2
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:
0x0 = 0 to 15 MHz
0x1 = 15 to 30 MHz
0x2 = 30 to 50 MHz
0x3 = 50 to 100 MHz
29-27
RESERVED
R
0x0
26-16
RFSH
R/W
0x2EE
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.
15-10
RESERVED
R
0x0
9
SLEEP
R/W
0x0
Sleep Mode
0x0 = No effect.
0x1 = The SDRAM is put into low power state, but is self-refreshed.