Datasheet

The FREQ field must be configured according to the value that represents the range being used.
Based on the range selected, the number of external clocks used between certain operations (for
example, PRECHARGE or ACTIVATE) is determined. If a higher frequency is given than is used,
then the only downside is that the peripheral is slower (uses more cycles for these delays). If a lower
frequency is given, incorrect operation occurs.
See “External Peripheral Interface (EPI)” on page 2129 for timing details for the SDRAM mode.
11.4.2.1 External Signal Connections
Table 11-3 on page 854 defines how EPI module signals should be connected to SDRAMs. The
table applies when using a x16 SDRAM up to 512 megabits. Note that the EPI signals must use
8-mA drive when interfacing to SDRAM, see page 805. Any unused EPI controller signals can be
used as GPIOs or another alternate function.
Table 11-3. EPI SDRAM x16 Signal Connections
SDRAM Signal
a
EPI Signal
D0A0EPI0S0
D1A1EPI0S1
D2A2EPI0S2
D3A3EPI0S3
D4A4EPI0S4
D5A5EPI0S5
D6A6EPI0S6
D7A7EPI0S7
D8A8EPI0S8
D9A9EPI0S9
D10A10EPI0S10
D11A11EPI0S11
D12A12
b
EPI0S12
D13BA0EPI0S13
D14BA1EPI0S14
D15EPI0S15
DQMLEPI0S16
DQMHEPI0S17
CASnEPI0S18
RASnEPI0S19
not usedEPI0S20-EPI0S27
WEnEPI0S28
CSnEPI0S29
CKEEPI0S30
CLKEPI0S31
a. If two signals are listed, connect the EPI signal to both pins.
b. Only for 256/512 megabit SDRAMs.
December 13, 2013854
Texas Instruments-Advance Information
External Peripheral Interface (EPI)