MC912DG128ACPVE Datasheet, PDF (107/478 Pages) Freescale Semiconductor, Inc – Upward compatible with M68HC11 instruction set

Freescale Semiconductor, Inc.
Bus Control and Input/Output
Registers
(R/W), IRQ, and XIRQ. 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 pull-ups (DBE, LSTRB,
R/W, IRQ and XIRQ). A single control bit enables the pull-ups for all
these pins which are configured as inputs.
This register is not in the map in peripheral mode or expanded modes
when the EME bit is set.
Read and write anytime.
DDRE — Port E Data Direction Register
$0009
Bit 7
6
5
4
3
2
1
DDE7
DDE6
DDE5
DDE4
DDE3
DDE2
0
RESET:
0
0
0
0
0
0
0
Bit 0
0
0
This register determines the primary direction for each port E pin
configured as general-purpose I/O.
0 = Associated pin is a high-impedance input
1 = Associated pin is an output
PE[1:0] 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.
Read and write anytime.
MC68HC912DT128A — Rev 4.0
MOTOROLA
Bus Control and Input/Output
For More Information On This Product,
Go to: www.freescale.com
Technical Data
107