LM3S2U93 Datasheet, PDF (483/1200 Pages) Texas Instruments – Stellaris® LM3S2U93 Microcontroller

Stellaris^® LM3S2U93 Microcontroller
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 1139 for timing details for the SDRAM mode.
10.4.1.1
External Signal Connections
Table 10-3 on page 483 defines how EPI module signals should be connected to SDRAMs. The
table applies when using a SDRAM up to 512 megabits. Note that the EPI signals must use 8-mA
drive when interfacing to SDRAM, see page 447. Any unused EPI controller signals can be used as
GPIOs or another alternate function.
Table 10-3. EPI SDRAM Signal Connections
EPI Signal
EPI0S0
EPI0S1
EPI0S2
EPI0S3
EPI0S4
EPI0S5
EPI0S6
EPI0S7
EPI0S8
EPI0S9
EPI0S10
EPI0S11
EPI0S12
EPI0S13
EPI0S14
EPI0S15
EPI0S16
EPI0S17
EPI0S18
EPI0S19
EPI0S20-EPI0S27
EPI0S28
EPI0S29
EPI0S30
EPI0S31
a. If 2 signals are listed, connect the EPI signal to both pins.
b. Only for 256/512 megabit SDRAMs
SDRAM Signal^a
A0
D0
A1
D1
A2
D2
A3
D3
A4
D4
A5
D5
A6
D6
A7
D7
A8
D8
A9
D9
A10
D10
A11
D11
A12^b
D12
BA0
D13
BA1
D14
D15
DQML
DQMH
CASn
RASn
not used
WEn
CSn
CKE
CLK
January 23, 2012
483
Texas Instruments-Production Data