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P4080 Development System User’s Guide, Rev. 0
Freescale Semiconductor
57
Programming Model
7.1.19
Switch Registers (PX_SW
x
)
The switch registers (PX_SWx) are used to define configuration switch overrides. Each bit in each
PX_SWx register corresponds to a similarly named switch on the board. If a bit is 1, the switch is 1 and
vice-versa, provided the matching ENx bit is set.
Note that SW registers do NOT reflect the contents of the physical switches.
7.1.20
Switch Enable Registers (PX_EN
x
)
The switch enable register (PX_ENx) control whether the corresponding bits of the corresponding
PX_SWx register are used or ignored.
7.2
EEPROM Data
The SystemID EEPROM stores important data about the Expedition system, including the following:
•
Board ID
•
Errata level (as shipped)
•
Manufacturing date
Offset 0x20, 0x22, 0x24, ...
Access: Read/Write
0
1
2
3
4
5
6
7
R
SWx #1
SWx #2
SWx #3
SWx #4
SWx #5
SWx #6
SWx #7
SWx #8
W
Reset
All zeros
Figure 44. Switch Registers (PX_SW
x
)
Table 42. PX_SW
x
Field Descriptions
Bits
Name
Description
0–7
SWx #b
Value to replace for switch SWx #b.
Offset 0x21, 0x23, 0x25, ...
Access: Read/Write
0
1
2
3
4
5
6
7
R
ENx #1
ENx #2
ENx #3
ENx #4
ENx #5
ENx #6
ENx #7
ENx #8
W
Reset
All zeros
Figure 45. Switch Enable Register (PX_EN
x
)
Table 43. PX_EN
x
Field Descriptions
Bits
Name
Description
0–7
ENx #b
0 External switch SWx #b controls the corresponding configuration pin; the system controller does
not affect the value.
1 Internal register SWx #b controls the corresponding configuration pin; the external switches do not
affect the value.