Motorola DragonBall MC68328 User Manual page 102

Parallel Ports
DIRECTION- DIR[7:0]
These bits control the pin directions. While high, the pins are outputs; while low, the pins
are inputs. These bits reset to 0 and have no function while the SELECT bits are low.
DATA- D[7:0]
These bits control or report the data on the pins while the associated SELECT bits are
high. While the DIRECTION bits are high, the DATA bits control the pins. While the DI-
RECTION bits are low, the pin levels are reported. These bits reset to 0 while the SELECT
bits are low. The data bits may be written at any time. Bits that are configured as inputs
will accept the written data but it will not be accessible until the respective pins are con-
figured as outputs. The actual value on the pin is reported when these bits are read.
SELECT[7:0]
These bits select whether interrupt or port I/O signals are connected to the pins. While
high, the port I/O function is connected to the pin; while low, the interrupt functions are
connected. The I/O functions are enabled after reset.
PULLUP- PU[7:0]
These bits enable the pullup resistors on the port. While high, the pullup resistors are en-
abled; while low, the pullup resistors are disabled. The pullups are enabled on reset.
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