mc68hc705e5 Freescale Semiconductor, Inc, mc68hc705e5 Datasheet - Page 51

• Manufacturer Part Number: mc68hc705e5
• Description: M68hc05 Family Of Microcontrollers Mcus
• Manufacturer: Freescale Semiconductor, Inc

7.1 Contents
7.2 Introduction
7.3 Port A
MC68HC705E5
General Release Specification — MC68HC705E5
—
Rev. 1.0
7.2
7.3
7.4
7.5
7.6
In single-chip mode, 20 lines are arranged as two 8-bit input/output (I/O)
ports and one 4-bit I/O port. These ports are programmable as either
inputs or outputs under software control of the data direction registers.
To avoid a glitch on the output pins, write data to the I/O port data
register before writing a one to the corresponding data direction register
(DDR).
Port A is an 8-bit bidirectional port which does not share any of its pins
with other subsystems. The port A data register is at $0000 and the DDR
is at $0004. 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.
Freescale Semiconductor, Inc.
For More Information On This Product,
Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .51
Port A . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .51
Port B . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .52
Port C . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .52
Input/Output Programming . . . . . . . . . . . . . . . . . . . . . . . . . . . .52
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Section 7. Input/Output (I/O) Ports
Input/Output (I/O) Ports
General Release Specification