MC68HC05C8A Datasheet, PDF (57/158 Pages) Motorola, Inc – Microcontrollers

7.5 Port C
Input/Output (I/O) Ports
Port C
Port C is an 8-bit bidirectional port. The port C data register is at $0002
and the data direction register (DDR) is at $0006. Reset does not affect
the data registers, but clears the data direction registers, thereby
returning the ports to inputs. Writing a 1 to a DDR bit sets the
corresponding port bit to output mode. PC7 has a high current sink and
source capability.
7.6 Port D
Port D is a 7-bit fixed input port. Four of its pins are shared with the SPI
subsystem, two more are shared with the SCI subsystem. Reset does
not affect the data registers. During reset, all seven bits become valid
input ports because all special function output drivers associated with
the SCI, timer, and SPI subsystems are disabled.
7.7 Input/Output Programming
I/O port pins may be programmed as inputs or outputs under software
control. The direction of the pins is determined by the state of the
corresponding bit in the port data direction register (DDR). Each I/O port
has an associated DDR. Any I/O port pin is configured as an output if its
corresponding DDR bit is set to a logic 1. A pin is configured as an input
if its corresponding DDR bit is cleared to a logic 0.
At power-on or reset, all DDRs are cleared, which configures all I/O pins
as inputs. The data direction registers are capable of being written to or
read by the processor. During the programmed output state, a read of
the data register actually reads the value of the output data latch and not
the I/O pin. For further information, refer to Table 7-1 and Figure 7-2.
MC68HC05C8A • MC68HCL05C8A • MC68HSC05C8A — Rev. 5.0
MOTOROLA
Input/Output (I/O) Ports
Technical Data
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