MC68HC05E5 Datasheet, PDF (50/140 Pages) Freescale Semiconductor, Inc – General Release Specification

Freescale Semiconductor, Inc.
Input/Output (I/O) Ports
7.4 Port B
Port B is an 8-bit bidirectional port which does share some of its pins with
other subsystems. The address of the port B data register is $0001 and
the DDR is at address $0005. 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. Refer to Section 11. Motorola Bus (M Bus) Interface and
Section 12. Synchronous Serial Interface (SSI) for descriptions of
port B behavior while either module is enabled.
7.5 Port C
Port C is a 4-bit bidirectional port which does not share any of its pins
with other subsystems. The port C data register is at $0002 and the 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 one to
a DDR bit sets the corresponding port bit to output mode.
7.6 Input/Output Programming
Ports A, B, and C 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 DDR with each port having an
associated DDR. Any port A, port B, or port C 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 port A,
B, and C pins as inputs. The data direction registers are capable of being
written to or read from 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. See Table 7-1 and Figure 7-1.
General Release Specification
Input/Output (I/O) Ports
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MC68HC05E5 — Rev. 1.0