MC68HC705C9A_1 Datasheet, PDF (65/157 Pages) Freescale Semiconductor, Inc – General Release Specification

7.5 Port C
7.6 Port D
Freescale Semiconductor, Inc.
General Release Specification
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. The contents of the
port C data register are indeterminate at initial powerup and must be
initialized by user software. Reset does not affect the data registers, but
clears the data direction registers, thereby returning the ports to inputs.
Writing a one to a DDR bit sets the corresponding port bit to output
mode. PC7 has a high current sink and source capability. Figure 7-1 is
also applicable to port C.
When configured as a C9A, port D is a 7-bit bidirectional port; when
configured as a C12A, port D is a 7-bit fixed input port. Four of its pins
are shared with the SPI subsystem and two more are shared with the
SCI subsystem. The contents of the port D data register are
indeterminate at initial powerup and must be initialized by user software.
During reset all seven bits become valid input ports because the C9A
DDR bits are cleared and the special function output drivers associated
with the SCI and SPI subsystems are disabled, thereby returning the
ports to inputs. Writing a one to a DDR bit sets the corresponding port
bit to output mode only when configured as a C9A.
MC68HC705C9A — Rev. 2.0
Input/Output Ports
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