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ꢊ ꢋ ꢌꢍ ꢎꢏꢐ ꢑꢋ ꢒ ꢀ ꢎ ꢋ ꢓꢋ ꢀꢔꢕ ꢂ ꢋ ꢓꢒ ꢔꢕ ꢐ ꢖꢑ ꢇꢍꢂ ꢂꢑ ꢖ
SPRS080F − MARCH 1999 − REVISED OCTOBER 2008
software-programmable wait-state generator (continued)
Table 2. Software Wait-State Register (SWWSR) Bit Fields
BIT
RESET
VALUE
FUNCTION
NO.
NAME
Extended program address control bit. XPA is used in conjunction with the program space fields
(bits 0 through 5) to select the address range for program space wait states.
15
XPA
0
1
I/O space. The field value (0−7) corresponds to the base number of wait states for I/O space accesses
within addresses 0000−FFFFh. The SWSM bit of the SWCR defines a multiplication factor of 1 or 2 for
the base number of wait states.
14−12
11−9
8−6
I/O
Upper data space. The field value (0−7) corresponds to the base number of wait states for external
data space accesses within addresses 8000−FFFFh. The SWSM bit of the SWCR defines a
multiplication factor of 1 or 2 for the base number of wait states.
Data
Data
1
1
Lower data space. The field value (0−7) corresponds to the base number of wait states for external
data space accesses within addresses 0000−7FFFh. The SWSM bit of the SWCR defines a
multiplication factor of 1 or 2 for the base number of wait states.
Upper program space. The field value (0−7) corresponds to the base number of wait states for external
program space accesses within the following addresses:
-
-
XPA = 0: x8000 − xFFFFh
5−3
2−0
Program
Program
1
1
XPA = 1: The upper program space bit field has no effect on wait states.
The SWSM bit of the SWCR defines a multiplication factor of 1 or 2 for the base number of wait
states.
Program space. The field value (0−7) corresponds to the base number of wait states for external
program space accesses within the following addresses:
-
-
XPA = 0: x0000−x7FFFh
XPA = 1: 00000−3FFFFh
The SWSM bit of the SWCR defines a multiplication factor of 1 or 2 for the base number of wait
states.
The software wait-state multiplier bit of the software wait-state control register (SWCR) is used to extend the
base number of wait states selected by the SWWSR. The SWCR bit fields are shown in Figure 4 and described
in Table 3.
15
1
0
SWSM
Reserved
R/W-0
R/W-0
LEGEND: R = Read, W = Write
Figure 4. Software Wait-State Control Register (SWCR) [MMR Address 002Bh]
Table 3. Software Wait-State Control Register (SWCR) Bit Fields
PIN
NAME
RESET
VALUE
FUNCTION
NO.
15−1
Reserved
0
These bits are reserved and are unaffected by writes.
Software wait-state multiplier. Used to multiply the number of wait states defined in the SWWSR by a factor
of 1 or 2.
0
SWSM
0
-
-
SWSM = 0: wait-state base values are unchanged (multiplied by 1).
SWSM = 1: wait-state base values are mulitplied by 2 for a maximum of 14 wait states.
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