Datasheet

When a shared analog function is enabled for a pin, all digital pin functions are disabled.
A read of the port data register returns a value of 0 for any bits that have shared analog
functions enabled. In general, whenever a pin is shared with both an alternate digital
function and an analog function, the analog function has priority such that if both of the
digital and analog functions are enabled, the analog function controls the pin.
A write of valid data to a port data register must occur before setting the output enable bit
of an associated port pin. This ensures that the pin will not be driven with an incorrect
data value.
7.3 Internal pullup enable
An internal pullup device can be enabled for each port pin by setting the corresponding
bit in one of the pullup enable registers (PTxPEn). The internal pullup device is disabled
if the pin is configured as an output by the parallel I/O control logic, or by any shared
peripheral function, regardless of the state of the corresponding pullup enable register bit.
The internal pullup device is also disabled if the pin is controlled by an analog function.
NOTE
When configuring IIC to use "SDA(PTA2) and SCL(PTA3)"
pins, and if an application uses internal pullups instead of
external pullups, the internal pullups remain present setting
when the pins are configured as outputs, but they are
automatically disabled to save power when the output values
are low.
7.4 Input glitch filter setting
A filter is implemented for each port pin that is configured as a digital input. It can be
used as a simple low-pass filter to filter any glitch that is introduced from the pins of
GPIO, IRQ, RESET, and KBI. The glitch width threshold can be adjusted easily by
setting registers PORT_IOFLTn and PORT_FCLKDIV between 1~4096 BUSCLKs (or
1~128 LPOCLKs). This configurable glitch filter can take the place of an on board
external analog filter, and greatly improve the EMC performance.
Setting register PORT_IOFLTn can configure the filter of the whole port, etc. set
PORT_IOFLT0[FLTA] will affect all PTAn pins.
Internal pullup enable
MC9S08PA60 Reference Manual, Rev. 1, 9/2012
154 Freescale Semiconductor, Inc.