MOTOROLA
EXTERNAL INTERFACE MODULE
MMC2001
7-8
REFERENCE MANUAL
X = Undefined
* PA reset value equals zero for CS3 and one for CS[1:2]
Figure 7-4 CS1, CS2, CS3 Control Registers
WSC — Wait-State Control
These four bits program the number of wait states for an access to the external device
connected to the chip select. Table 7-4 shows the encoding of this field. When WWS
is cleared, setting WSC=0000 results in 1-clock transfers, WSC=0001 results in 2-
clock transfers, and WSC=1111 results in 16-clock transfers. When WSC=0000, the
WEN and CSA bits are ignored.
Set WSC=0000 and WWS=0 for access to fast SRAM devices (one-clock read and
write access), CSA=0, WSC=0001 and WWS=0 for access to normal SRAM (two-
clock read and write access), CSA=0, WSC=0001 and WWS=1 for access to Flash
memory (two-clock read access and three-clock write access), EDC, CSA and WSC
to the appropriate number for access to an LCD controller.
CS1CR — CS1 Control Register
10004004
CS2CR — CS2 Control Register
10004008
CS3CR — CS3 Control Register
1000400C
31
30
29
28
27
26
25
24
23
22
21
20
19
18
17
16
R
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
W
RESET:
15
14
13
12
11
10
9
8
7
6
5
4
3
2
1
0
R
WSC
WWS
EDC
CSA
OEA
WEN
EBC
DSZ
SP
WP
PA
CSEN
W
RESET:
X
X
X
X
X
X
X
X
X
X
X
X
X
X
0/1*
0
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I
Freescale Semiconductor, Inc.
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