XC912BC32CFU8 Motorola Semiconductor Products, XC912BC32CFU8 Datasheet - Page 94

• Manufacturer Part Number: XC912BC32CFU8
• Description: M68HC12B Family Data Sheet
• Manufacturer: Motorola Semiconductor Products

Bus Control and Input/Output (I/O)
6.3.8 Pullup Control Register
Data Sheet
94
RDWE — Read/Write Enable Bit
Read: Anytime, if register is in the map
Write: Anytime, if register is in the map
These bits select pullup resistors for any pin in the corresponding port that is
currently configured as an input. This register is not in the map in peripheral mode.
PUPE — Pullup Port E Enable Bit
PUPB — Pullup Port B Enable Bit
PUPA — Pullup Port A Enable Bit
Normal: Write once
Special: Write anytime except the first time
This bit has no effect in single-chip modes.
R/W is used for external writes. After reset in normal expanded mode, it is
disabled. If needed, it should be enabled before any external writes.
Pin PE1 always has a pullup. Pins PE6, PE5, and PE4 never have pullups.
This bit has no effect if port B is used as part of the address/data bus (pullups
are inactive).
This bit has no effect, if port A is used as part of the address/data bus (pullups
are inactive).
Address: $000C
Reset:
Read:
Write:
1 = PE2 configured as R/W pin
0 = PE2 configured as general-purpose I/O pin
1 = Enable port E pullups on PE7, PE3, PE2, PE1, and PE0
0 = Disable port E pullups on PE7, PE3, PE2, PE1, and PE0
1 = Enable pullups for all port B input pins
0 = Disable port B pullups
0 = Disable port A pullups
1 = Enable pullups for all port A input pins
Bit 7
0
0
Bus Control and Input/Output (I/O)
Figure 6-8. Pullup Control Register (PUCR)
= Unimplemented
6
0
0
5
0
0
PUPE
4
1
3
0
0
M68HC12B Family — Rev. 8.0
2
0
0
PUPB
1
0
MOTOROLA
PUPA
Bit 0
0