XC912BC32CFU8 Motorola Semiconductor Products, XC912BC32CFU8 Datasheet - Page 91

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

6.3.6 Port E Data Direction Register
M68HC12B Family — Rev. 8.0
MOTOROLA
When the associated pin is not used for one of these specific functions, the pin can
be used as general-purpose I/O. The port E assignment register (PEAR) selects
the function of each pin. DDRE determines the primary direction of each port E pin
when configured to be general-purpose I/O.
Some of these pins have software selectable pullups (DBE, LSTRB, R/W, and
XIRQ). A single control bit enables the pullups for all these pins which are
configured as inputs. IRQ always has a pullup.
This register is not in the map in peripheral mode or expanded modes when the
EME bit is set.
Read: Anytime, if register is in the map
Write: Anytime, if register is in the map
This register determines the primary direction for each port E pin configured as
general-purpose I/O.
PE1 and PE0 are associated with XIRQ and IRQ and cannot be configured as
outputs. These pins can be read regardless of whether the alternate interrupt
functions are enabled.
This register is not in the map in peripheral mode and expanded modes while the
EME control bit is set.
Address: $0009
Reset:
Read:
Write:
1 = Associated pin is an output.
0 = Associated pin is a high-impedance input.
DDE7
Figure 6-6. Port E Data Direction Register (DDRE)
Bit 7
0
Bus Control and Input/Output (I/O)
= Unimplemented
DDE6
6
0
DDE5
5
0
DDE4
4
0
DDE3
3
0
Bus Control and Input/Output (I/O)
DDE2
2
0
1
0
0
Data Sheet
Registers
Bit 0
0
0
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