EMIF Registers
654
SPNU503C – March 2018
Copyright © 2018, Texas Instruments Incorporated
External Memory Interface (EMIF)
17.3.5 Asynchronous n Configuration Registers (CE2CFG-CE5CFG)
The asynchronous
n
configuration registers (CE2CFG, CE3CFG, CE4CFG, and CE5CFG) are used to
configure the shaping of the address and control signals during an access to asynchronous memory
connected to CS2, CS3, CS4, and CS5, respectively. CS5 is not available on this device. It is also used to
program the width of asynchronous interface and to select from various modes of operation. This register
can be written prior to any transfer, and any asynchronous transfer following the write will use the new
configuration. The CE
n
CFG is shown in
and described in
Figure 17-19. Asynchronous n Configuration Register (CEnCFG) [offset = 10h - 1Ch]
31
30
29
26
25
24
SS
EW
(A)
W_SETUP
W_STROBE
(B)
R/W-0
R/W-0
R/W-Fh
R/W-3Fh
23
20
19
17
16
W_STROBE
(B)
W_HOLD
R_SETUP
R/W-3Fh
R/W-7h
R/W-Fh
15
13
12
7
6
4
3
2
1
0
R_SETUP
R_STROBE
(B)
R_HOLD
TA
ASIZE
R/W-Fh
R/W-3Fh
R/W-7h
R/W-3h
R/W-0
LEGEND: R/W = Read/Write; R = Read only; -
n
= value after reset
A. The EW bit must be cleared to 0.
B. This bit field must be cleared to 0 if the EMIF on your device does not have an EMIF_nWAIT pin.
Table 17-29. Asynchronous n Configuration Register (CEnCFG) Field Descriptions
Bit
Field
Value
Description
31
SS
Select Strobe bit. This bit defines whether the asynchronous interface operates in Normal Mode or
Select Strobe Mode. See
for details on the two modes of operation.
0
Normal Mode is enabled.
1
Select Strobe Mode is enabled.
30
EW
Extend Wait bit. This bit defines whether extended wait cycles will be enabled. See
on
extended wait cycles for details. This bit field must be cleared to 0, if the EMIF on your device does not
have an EMIF_nWAIT pin.
0
Extended wait cycles are disabled.
1
Extended wait cycles are enabled.
29-26
W_SETUP
0-Fh
Write setup width in EMIF_CLK cycles, minus 1 cycle. See
for details.
25-20
W_STROBE
0-3Fh
Write strobe width in EMIF_CLK cycles, minus 1 cycle. See
for details.
19-17
W_HOLD
0-7h
Write hold width in EMIF_CLK cycles, minus 1 cycle. See
for details.
16-13
R_SETUP
0-Fh
Read setup width in EMIF_CLK cycles, minus 1 cycle. See
for details.
12-7
R_STROBE
0-3Fh
Read strobe width in EMIF_CLK cycles, minus 1 cycle. See
for details.
6-4
R_HOLD
0-7h
Read hold width in EMIF_CLK cycles, minus 1 cycle. See
for details.
3-2
TA
0-3h
Minimum Turn-Around time. This field defines the minimum number of EMIF_CLK cycles between reads
and writes, minus 1 cycle. See
for details.
1-0
ASIZE
Asynchronous Data Bus Width. This field defines the width of the asynchronous device data bus.
0
8-bit data bus
1h
16-bit data bus
2h-3h
Reserved