Datasheet

MC68HC908QY4•MC68HC908QT4•MC68HC908QY2•MC68HC908QT2•MC68HC908QY1•MC68HC908QT1
166 Input/Output (I/O) Ports MOTOROLA
Input/Output (I/O) Ports
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12.3.3 Port A Input Pullup Enable Register
The port A input pullup enable register (PTAPUE) contains a software
configurable pullup device for each if the six port A pins. Each bit is
individually configurable and requires the corresponding data direction
register, DDRAx, to be configured as input. Each pullup device is
automatically and dynamically disabled when its corresponding DDRAx
bit is configured as output.
OSC2EN — Enable PTA4 on OSC2 Pin
This read/write bit configures the OSC2 pin function when internal
oscillator or RC oscillator option is selected. This bit has no effect for
the XTAL or external oscillator options.
1 = OSC2 pin outputs the internal or RC oscillator clock
(BUSCLKX4)
0 = OSC2 pin configured for PTA4 I/O, having all the interrupt and
pullup functions
PTAPUE[5:0] — Port A Input Pullup Enable Bits
These read/write bits are software programmable to enable pullup
devices on port A pins.
1 = Corresponding port A pin configured to have internal pull if its
DDRA bit is set to 0
0 = Pullup device is disconnected on the corresponding port A pin
regardless of the state of its DDRA bit
Table 12-1 summarizes the operation of the port A pins.
Address: $000B
Bit 7654321Bit 0
Read:
OSC2EN
PTAPUE5 PTAPUE4 PTAPUE3 PTAPUE2 PTAPUE2 PTAPUE0
Write:
Reset:00000000
= Unimplemented
Figure 12-5. Port A Input Pullup Enable Register (PTAPUE)